sensor MITSUBISHI DIAMANTE 1900 Repair Manual

BRAKES 9-5
Inspect brake pedal free-play
firm that the amount of movement before resistance
is felt is within 0.1-0.3 in. (3-8mm).
3. If the free-play is less than desired, confirm
that the brake light switch is in proper adjustment.
4. If there is excessive free-play, look for wear or
play in the clevis pin and brake pedal arm. Replace
worn parts as required and recheck brake pedal free-
Play*
REMOVAL &INSTALLATION '
b See Figure 15
1. Disconnect the negative battery cable.
2. Siphon the brake fluid from the master cylin-
der reservoir.
Brake fluid contains polyglycol ethers and
polyglycols. Avoid contact with the eyes and
wash your hands thoroughly after handling
brake fluid. If you do get brake fluid in your
eyes, flush your eyes with clean, running wa-
. ter for 15 minutes. If eye irritation persists,
or if you have taken brake fluid internally,
IMMEDIATELY seek medical assistance.
3. Remove and relocate the air conditioning re-
lay box and the solenoid valve located at the power
brake unit.
4. Disconnect the vacuum hose from the
booster by pulling it straight off. Prying off the vac-
uum hose could damage the check valve installed in
the brake booster vacuum hose.
5. Detach the electrical harness connector from
the brake level sensor.
6. Remove the nuts attaching the master cylin-
der to the booster and remove the master cylinder
and position aside. If necessary, disconnect and plug
the brake fluid lines at the master cylinder.
7. From inside the passenger compartment, re-
move the cotter pin and clevis pin that secures the
booster pushrod to the brake pedal.
8. From inside the vehicle, remove the nuts that
attach the booster to the dash panel. Remove the
brake booster from the engine compartment.
To install: 9. Install the brake booster to the dash panel.
From inside the vehicle, install the attaching nuts and
tighten to 12 ft. Ibs. (17 Nm). 10. Apply grease to the clevis pin and install with
washers in place. Install new cotter pin and bend to
secure in place.
11. Attach the vacuum hose to the booster fitting.
12. Install the master cylinder assembly to the
mounting studs on the brake booster. Install the mas-
ter cylinder mounting nuts and tighten to 9 ft. Ibs. (12
Nm).
13. Reconnect the brake fluid reservoir to the
master cylinder, if disconnected. Attach the electrical
connector to the brake fluid level sensor.
14. Install the solenoid valve assembly and the
relay box, if removed.
15. Connect the negative battery cable.
16. Add fluid to the brake fluid reservoir as re-
quired.
Clean, high quality brake fluid is essentlal to
the safe and proper operation of the brake
system. You should always buy the highest
quality brake fluid that is available. If the
brake fluid becomes contaminated, drain and
flush the system, then refill the master cylin-
der with new fluid. Never reuse any brake
fluid. Any brake fluid that is removed from
the system should be discarded. Also, do not
allow any brake fluid to come in contact with
a painted surface; it will damage the paint.
17. Bleed the master cylinder. If after bleeding the
master cylinder the brake pedal feels soft, bleed the
brake system at all wheels.
18. Check the brake system for proper operation. *
rn( mr
'13 1. Relay box for air
conditioner
l-13 t- I, Ltx5. 5-18 NM 2. Solenoid valve
3. Brake fluid level
sensor connector
6 4. Brake tube
5. Master cylinder, hose
and reservoir
assem biy
Fig. 15 Exploded view of the power brake booster and related components-most models
12.
13.
14. Fitting 1
Cotter pin;
Washer 1
Clevis pin’ Fuel retuti tub8 installatiob bolt
Brake tUd8 installatioh bolt
Brake booster
Sealer
89579glt

9-24 BRAKES
Shoe-to-anchor spring (rear)
e Forward
69579946 Fig. 114 Shoe-to-anchor spring installation
*When servicing drum
brakes, only dissem-
ble and assemble one side at a time, leaving
the remaining side intact for reference.
4. Remove the front and rear shoe-to-anchor
springs.
5. Remove the adjusting wheel spring and the
adjuster.
6. Remove the strut and the strut return spring.
7. Remove the shoe hold-down cup, spring and
pin.
8. Remove the shoe and lining assembly.
9. Unfasten the clips and the retaining bolts,
then remove the parking brake cable(s).
To install: 10. Installation is the reverse of the removal pro-
cedure.
11. Install the adjuster so the shoe adjusting bolt
of the left hand wheel is attached toward the front of the vehicle and the shoe adjusting bolt of the right
hand wheel is toward the rear of the vehicle. -
12. The load on the respective shoe-to-anchor
springs is different, so the spring in the figure has
hen painteb, a> shm in the a~~0mparrying figure.
1997-00 Diamante
‘) See Figure 115
1. Raise and safely support the vehicle securely
on jackstands.
2. Remove the caliper assembly.
3. Remove the rear brake rotor.
*When servicing drum brakes, only dissem-
ble and assemble one side at a time, leaving
the remaining side intact for reference.
4. Remove the shoe hold-down spring retaining
screw.
5. Remove the shoe hold-down spring.
6. Remove the shoe assembly from the backing
plate.
7. The installation is the reverse of removal.
ADJUSTMENT
1. Remove the floor console, release the lever
and back off the cable adjuster locknut at the base of
the lever.
2. Raise the vehicle, support safely and remove
the wheel. 3. Remove the hole plug in the brake rotor.
4. Remove the brake caliper and hang out of the
way with wire. Do not disconnect the fluid line.
5. Use a suitable prybar to pry up on the self-ad-
juskr V&I&I unti tie T&IT wi\ not tirn.
6. Return the adjuster 5 notches in the opposite
direction. Make sure the rotor turns freely with a
slight drag.
7. Install the caliper and check operation.
9. Shoe 93159go3 Fig. 115 Exploded view of the parking brake
shoes and related components-l 997-00
Diamante
The 4-Wheel Anti-lock Brake System (ABS) is an
electronically operated, all wheel brake control sys-
tem. Major components include the vacuum power
brake booster, master cylinder, the wheel speed sen-
sors, the Hydraulic Control Unit (HCU), Anti-lock
control unit, a relay, and on the AWD Galant, a G sen-
sor.
The system is designed to retard wheel lockup
during periods of high wheel slip when braking. Re-
tarding wheel lockup is accomplished by modulating
fluid pressure to the wheel brake units. When the
control unit detects a variation in voltage across the
wheel speed sensors, the ABS is activated. The con-
trol unit opens and closes various valves located in-
side the HCU. These valves, called dump and isola-
tion valves, modulate the hydraulic pressure to the
wheels by applying and venting the pressure to the
brake fluid circuits.
PRECAUTIONS
l Certain components within the Anti-Lock Brake
System (ABS) are not intended to be serviced or re-
paired individually. Only those components with re- !
moval and installation procedures should be ser-
viced.
0 Do not use rubber hoses or other parts not
specifically specified for an ABS system. When using
repair kits, replace all parts included in the kit. Partial
or incorrect repair may lead to functional problems
and require the replacement of components.
l Lubricate rubber parts with clean, fresh brake
fluid to ease assembly. Do not use lubricated shop air
to clean parts; damage to rubber components may re-
sult.
l Use only specified brake fluid from an un-
opened container.
l If any hydraulic component or line is removed
or replaced, it may be necessary to bleed the entire
system.
l A clean repair area is essential. Always clean
the reservoir and cap thoroughly before removing the
cap. The slightest amount of dirt in the fluid may plug
an orifice and impair the system function. Perform re-
pairs after components have been thoroughly
cleaned; use only denatured alcohol to clean compo-
nents. Do not allow ABS components to come into
contact with any substance containing mineral oil;
this includes used shop rags.
l The Anti-Lock control unit is a microprocessor
similar to other computer units in the vehicle. Ensure
that the ignition switch is
OFF before removing or in-
stalling controller harnesses. Avoid static electricity
discharge at or near the controller.
l If any arc welding is to be done on the vehicle,
the control unit should be unplugged before welding
operations begin.
) See Figures 116 thru 123
The diagnosis of the ABS system is rather complex
and requires quite a few special tools including scan tools, special test harnesses and other special and
expensive tools. Alternative methods and common
sense can be substituted, however, We at Chilton feel
that it is beyond the scope of the average do-it-your-
selfer. If you experience the amber ANTI LOCK light
on in the instrument cluster of your vehicle, check the
fluid level in the master cylinder first. Low fluid level
will usually illuminate the red BRAKE lamp in the in-
strument cluster as well as, but not always, the amber
ANTI LOCK lamp in the instrument cluster. The low
fluid level could indicate a leak, but sometimes just
indicates low, worn brake linings that have caused the
caliper pistons and wheel cylinders to extend further,
and thus using more fluid to exert force on them. In-
spect the brake system for hydraulic fluid leaks and
also inspect the brake linings for excessive wear.
89579956 Fig. 116 You can connect a scan tool to the
data link connector to retrieve ABS trouble
codes

BRAKES 9-25
Diagnostic inspection item Diagnostic content
trouble
code No.
11 Right front wheel speed sensor
12 Left front wheel speed sensor Open circuit
13 Right rear wheel speed sensor
14 Left rear wheel speed sensor
Abnormal output signal
Abnormal battery posi-
tive voltage 15 Wheel speed sensor system
16 Power supply system
r 21
I Right front wheel speed sensor 1 Excessive gap
22 I Left front wheel speed sensor or short circuit
23 Right rear wheel speed sensor
24 Left rear wheel speed sensor
36 Stop light switch system Open circuit or ON mal-
function
Right front solenoid valve system
I 5’ I Valve relay system 1 Valve relay OFF failure
I 53 1 Motor relay or motor system Motor relay OFF failure
and motor drive failure
63 ABS-ECU Malfunction in ABS-
ECU (program maze,
etc.)
I
!
Detection
conditions
B ’
A, B
A, B
A, B
A, 8
B
A, B
Detection conditions
A: During system check immediately after starting
B: When driving
89579954 Fig. 117 ABS diagnostic trouble code list-1992-96 Diamante
Diagnostrc
trouble Inspection item Detectron
code no. condalons
1
11 1 Front right wheel speed SensOr
I
I I
12 1 Front left wheel speed sensor
13 1 Rear right wheel speed sensor Open circuit
lBsC I
14
Rear left wheel speed sensor
15 Wheel speed sensor output signal abnormal
16 Power supply system
21 Front right wheel speed sensor A B
A, B, C
22 Front left wheel speed sensor
23 Rear right wheel speed sensor
24 Rear left wheel speed sensor
38 Stop light switch system Short circuit
8, c
B. C
41 1 Front right solenoid valve (inlet)
I I
42
Front left solenoid valve (inlet)
43 Rear right solenord valve (inlet) 0.c
44 Rear left solenoid valve (inlet)
45 Front right solenoid valve (outlet)
46 Front left solenoid valve (outlet)
47
Rear nght solenoid valve (outret) - B,C
48 Rear left solenoid valve (outlet)
51
Valve relay A 6, c
53
Motor relay B
63 ABSECU A B, c
Detection conditions
A: During system check immediately after starting 6: While ABS control is not operating while driving C: While ABS control is operating 93159go4 Fig. 118 ABS diagnostic trouble code list-1997-00 Diamante
The ABS control unit performs system tests and
self-tests during startup and normal operation. The
valves, wheel sensors and fluid level circuits are
monitored for proper operation. If a fault is found, the ABS will be deactivated and the amber ANTI LOCK
light will be lit until the ignition is turned OFF. When
the light is lit, the Diagnostic Trouble Code (DTC)
may be obtained. Under normal operation, the ANTI-
89579g53 Fig. 119 ABS diagnostic trouble code list-
1990-93 Galant
LOCK warning lamp will flash either twice (FWD) or 4
times (AWD) vehicles, in about 1 second with the ig-
,
nition switch ON , then the lamp will turn OFF.
The Diagnostic Trouble Codes (DTC) are an al-
phanumeric code and a scan tool, such as DRB-III,
MUT-II or equivalent diagnostic scan tool, is required
to retrieve the codes. Refer to the scan tool manufac-
turers instructions for operating the tool and retriev-
ing the codes.
The Data Link Connector (DLC) for the ABS is lo-
cated under the dash on the driver’s side. It is the
same connector used for the electronic engine con-
trol system.
REMOVALANDINSTALLATION
The Hydraulic Control Unit (HCU) is located in the
engine compartment. It contains the solenoid valves
and the pump/motor assembly which provides pres-
surized fluid for the anti-lock system when necessary.
Hydraulic units are not interchangeable on any vehi-
cles Neither unit is serviceable; if any fault occurs
within the hydraulic unit, the entire unit must be re-
placed.
Diamante
b See Figure 124
1. Disconnect the negative battery cable.
2. Remove the splash shield from beneath the
vehicle.
3. Use a syringe or similar device to remove as
much fluid as possible from the reservoir. Some fluid
will be spilled from lines during removal of the hy-
draulic unit; protect adjacent painted surfaces.
Brake fluid contains polyglycol ethers and
poly9lycols. Avoid contact with the eyes and
wash your hands thoroughly after handling
brake fluid. If you do 9et brake fluid in your
eyes, flush your eyes with clean, running wa-
ter for 15 minutes. If eye irritation persists,
or if you have taken brake fluid internally,
IMMEDIATELY seek medical assistance.
4. Lift the relay box with the harness attached
and position it aside.
5. Remove the air intake duct.
6. Disconnect the brake lines from the hydraulic
unit. Correct reassembly is critical. Label or identify
the lines before removal. Plug each line immediately

Diagnostic InspeclM item
trouble
code no. Detection
conditions
11 Front right wheel speed sensor
12 Front left wheel speed sensor
13 Rear right wheel speed sensor Open circuit
6 c
14
Rear left wheel speed sensor
16
Power supply system
21 Front right wheel speed sensor
22 Front left wheel speed sensor Short circuit 4 0. C
0, c
23
Rear right wheel speed sensof
24 Rear left wheel speed sensor
25 Front right wheel speed sensor
26 Front left wheel speed sensor Excessive gap
B, c
27 / Rear right wheel speed sensor
26 1 Rear left wheel speed sew
33
Stop light switch system
35 Front right wheel speed sensor
36 Front left wheel speed sensor
37 Rear right wheel speed sensor Pulse orocessina
pheei speed in&t
corresponding to a
vehicle speed of 300
46 Rear left solenoid valve (outside)
51
Valve relay
52 Vti relay
53
Motor relay
54
Motor relay ON impossible ,
A B. C
OFF impossrble
A
ON impossible
B
OFF impossible
B, c
Detection conditions A: During system check immediately after starting
8: While ABS control is not operating while driving
C: While ABS control is operating
Fig. 120 ABS diagnostic trouble code list-1994-98 Galant 93159go5
DIAGNOSTIC INSPECTION IT’EH DIAGNOSTIC CONTENT
TROUBLE
CODE NO.
11 Front right wheel speed
Sensor Open circuit or short circuit
12
13 Front left wheel speed sensor
Rear right wheel speed
SBnsor
14
16 Fear left wheel speed ssnsor
Power supply system ABS-ECU power supply
voltage below or above the
standard value. Not displayed
if the voltage recovers.
21 Front right wheel speed sensor
22 Front left wheel speed sensor
23 Rear right whesl sped sensor
~
Hydraulic unit aolenoid valve relay open or short circuit
93159906
Fig. 121 ABS diagnostic trouble code list-1999-00 Galant Fig. 122 ABS diagnostic trouble code list-1993-96 Mirage

9-28 BRAKES
1. Electronic control una
2. Bracket 93159912 Fig. 127 Anti-lock control unit mounting-
Fig. 128 Anti-lock control unit mounting-
Mirage
Galant and Diamante
REMOVAL&INSTALLATION
Mirage
FRONT
I) See Figure 129
1, Disconnect the negative battery cable.
Wait at least 90 seconds after the negative
battery cable is disconnected to prevent pos-
sible deployment of the air bag.
2. Raise and safely support the vehicle.
3. Remove the splash shield.
4. Detach the speed sensor connector.
5. Remove the clips holding the sensor harness.
6. Remove the speed sensor from the bracket.
To install: 7. Install the speed sensor to the bracket and
secure with mounting bolt.
8. Install the clips holding the sensor harness.
9. Attach the speed sensor connector.
IO. Connect the negative battery cable.
REAR
8 See Figure 129 and 130
1. Disconnect the negative battery cable.
Wait at least 90 seconds after the negative
battery cable is disconnected to prevent pos-
sible deployment of the air bag.
2. Raise and safely support the vehicle.
3. Detach the speed sensor connector.
4. Remove the clips holding the sensor harness.
5. Remove the mounting bolt and the speed
sensor.
To install: 6. Install the speed sensor and loosely tighten
the mounting bolt,
7. Install the clips holding the sensor harness.
1. ABS-ECU ccr~nector
2. ABSECU
3. Bracket
8. Install the sensor wire harness and attach the
connector,
9. Using a non-magnetic feeler gauge, adjust
the sensor air gap so the clearance between the rotor
and the sensor is 0.012-0.035 inches (0.3-0.9mm).
IO. Tighten the sensor bracket and recheck the
clearance.
11. Connect the negative battery cable.
Fig. 129 Front and rear wheel speed sen-
sors-Mirage
1
3. Front speed sensor connwxwn
4 Fmnt sweed sensor
5 Front speed sensor bracket
6 Rear toothed rotor 8 Cabletand
8 Rear speed sensor connection
10 Rear speed sensx
12 omg
93159934 Fig. 131 Wheel speed sensors-1990-93
RWD Galant Galant
FRONT
# See Figures 131 and 132
1. Disconnect the negative battery cable. Wait at
least 90 seconds before performing any work.
2. Raise and safely support the vehicle. Remove
the necessary tire and wheel assembly.
3. Remove the fender splash shield.
4. Detach the ABS speed sensor connector.
5. Remove the sensor harness clamp bolts and
clamps.
6. Remove the ABS speed sensor mounting bolt
and the sensor.
To install: 7. Install the ABS speed sensor with its mount-
ing bolt.
*The clearance between the wheel speed
sensor and the rotor’s toothed surface is not
adjustable, but measure the distance be-
tween the sensor installation surface and the
rotor’s toothed surface. Standard value is:
1.11-1 .I2 in. (28.2-28.4mm). If not within
specifications, replace the speed sensor or
the toothed rotor.
Speed sensor
Feeler gauge
93159g35
Fig. 130 Adjusting the rear speed sensor air
gap-Mirage
6
Fig. 132 Wheel speed sensors-1994-00
Galant

BRAKES 9-29
8. Reinstall the sensor harness with its clamps
and bolts.
9. Reconnect the speed sensor connector.
IO. Install the fender splash shield.
11. Reinstall the tire and wheel, safely lower the
vehicle, and reconnect the negative battery cable. To install: 7. Install the speed sensor and torque to 9 ft.
Ibs. (12 Nm).
8. Install the clips holding the sensor harness.
9. Connect the speed sensor connector.
IO. Connect the negative battery cable.
REAR REAR
) See Figure 131 and 132
1. Disconnect the negative battery cable. Wait at
least 90 seconds before performing any work.
2. Raise and safely support the vehicle. Remove
the necessary tire and wheel assembly.
3. Detach the ABS speed sensor connector.
4. Remove the sensor harness clamp bolts and
clamps.
I) See Figure 133
1. Disconnect the negative battery cable.
5. Remove the ABS speed sensor mounting bolt
and the sensor.
Work must be started after 90 seconds from
the time the ignition switch is turned to the
LOCK position and the negative battery cable
is disconnected.
To install:
6. Install the ABS speed sensor with its mounting
bolt.
*The clearance between the wheel speed
sensor and the rotor’s toothed surface is not
adjustable, but measure the distance be-
tween the sensor installation surface and the
rotor’s toothed surface. Standard value is:
1.11-l .I2 in. (28.2-28.4mm). If not within
specifications, replace the speed sensor or
the toothed rotor.
2. Raise and safely support the vehicle.
3. Detach the speed sensor connector.
4. Remove the clips holding the sensor harness.
5. On AWD models, remove the cable band.
6. Remove the mounting bolt and the speed
sensor with the O-ring.
To install: 7. Install the speed sensor with the O-ring and
torque to 9 ft. Ibs. (12 Nm).
8. Install the clips holding the sensor harness.
9. Install the cable band.
10. Install the sensor wire harness and connect
the connector.
7. Reinstall the sensor harness with its clamps
and bolts.
8. Reconnect the speed sensor connector.
9. Reinstall the tire and wheel, safely lower the
vehicle, and reconnect the negative battery cable.
Diamante
FRONT
* See Figure 133
1. Disconnect the negative battery cable.
Work must be started after 90 seconds from
the time the ignition switch is turned to the
LOCK position and the negative battery cable
is disconnected.
2. Raise and safely support the vehicle.
3. Remove the splash shield.
4. Detach the speed sensor connector.
5. Remove the clips holding the sensor harness.
6. Remove the speed sensor.
1 Front toothed rotor
2 Ckp
3 Front speed sensor
4 Front speed aenmr bracket t ;5’ toothed rotor ‘I Rear speed SB"SO,
93159016
Fig. 133 Wheel speed sensors-Diamante
11. Connect the negative battery cable.
The G-sensors are used only on the AWD vehi-
cles. The rear is mounted in the trunk under the floor
mat while the front sensor is under the console as-
sembly. The sensor transmits acceleration and decel-
eration information to the anti-lock control unit. This
data is used in conjunction with individual wheel
speed and engine data, allowing the controller to de-
termine the approximate road friction. This friction
factor is then used to compute the proper control of
the solenoid valves.
REMOVAL&INSTALLATION
# See Figure 134
1. For the front sensor, remove the console as-
sembly.
-lkol*)
1 wimp--vx
2 Gasnan I‘m”0
3. Gmwor LmcM
Bmar burl
: wwzh&T&m~mm-
6 G.smsol Ired Th, - ape.24 m-5 un Nt- vmsa*.
7 c-.elwnbRcta
93159909 Fig. 134 Front and rear G-sensor mount-
ing-l 990-93 AWD Galant
2. For the rear sensor, remove the trunk floor
mat.
3. Disconnect the G-sensor wiring harness.
4. Remove the cover from the rear sensor. Re-
move the sensor from the bracket. Remove the
bracket if desired.
To install: 5. Reinstall the bracket if it was removed.
6. Install the G-sensor and connect the wiring
harness. Tighten the retaining bolts to 8 ft. Ibs. (11
Nm).
7. Install the cover on the rear G-sensor.
8, Install the console and/or the trunk floor mat or
carpet.
REMOVAL & INSTALLATION
Front
1. Raise and safely support the vehicle.
2. Remove the wheel and tire.
3. Remove the wheel speed sensor and discon-
nect sufficient harness clips to allow the sensor and
wiring to be moved out of the work area.
*The speed sensor has a pole piece project-
ing from it. This exposed tip must be pro-
tected from impact or scratches. Do not al-
low the pole piece to contact the toothed
wheel during removal or installation.
4. Remove the front hub and knuckle assembly.
5. Remove the hub from the knuckle.
6. Support the hub in a vise with protected jaws.
7. Remove the retaining bolts from the toothed
wheel and remove the toothed wheel.
To install: 8. Fit the new toothed wheel onto the hub and
tighten the retaining bolts to 7 ft. Ibs. (10 Nm).
9. Assemble the hub to the knuckle
IO. Install the hub and knuckle assembly to the
vehicle.
11. Install the wheel speed sensor.
12. Install the wheel and tire.
13. Lower the vehicle to the ground.
Rear
EXCEPT AWD GALANT
1. Raise and safely support the vehicle.
2. Remove the wheel and tire.
3. Remove the wheel speed sensor and discon-
nect sufficient harness clips to allow the sensor and
wiring to be moved out of the work area.
*The speed sensor has a pole piece project-
ing from it. This exposed tip must be pro-
tected from impact or scratches. Do not al-
low the pole piece to contact the toothed
wheel during removal or installation.
4. Remove the hub assembly.
5. Support the hub in a vise with protected jaws.
6. Remove the retaining bolts from the toothed
wheel and remove the toothed wheel.
To install: 7. Fit the new toothed wheel onto the hub and
tighten the retaining bolts to 7 ft. Ibs. (10 Nm).
8. Install the hub assembly to the vehicle. The
center hub nut is not reusable. The new nut must be

9-30 BRAKES
tightened to 144-188 ft. Ibs. (200-260 Nm). After the
nut is tightened, align the nut with the spindle inden-
tation and crimp the nut in place.
9. Install the wheel speed sensor.
10. Install the wheel and tire.
11. Lower the vehicle to the ground.
AWD GALANT
1. Raise and safely support the vehicle.
2. Remove the wheel and tire.
3. Disconnect the parking brake cable from the
caliper.
4. Remove the speed sensor and its O-ring.
Disconnect sufficient clamps and wire ties to allow
the sensor to be moved well out of the work area.
*The speed sensor has a pole piece project-
ing from it. This exposed tip must be pro-
tected from impact or scratches. Do not al-
low the pole piece to contact the toothed
wheel during removal or installatlon.
5. Remove the brake caliper and brake disc.
6. Remove the 3 retaining nuts and bolts hold-
ing the outer end of the driveshaft to the companion
flange.
7. Swing the axle shaft away and support it with
stiff wire. Do not overextend the joint in the axle; do
not allow it to hang unsupported.
, 8. Remove the retaining nut and washer on the
back of the driveshaft. Use special tool MB 9967 or
equivalent to counterhold the hub.
9. Remove the companion flange from the
knuckle.
IO. Using an axle puller which bolts to the wheel
lugs, remove the axle shaft assembly.
11. Fit the shaft assembly in a press with the
toothed wheel completely supported by a bearing
plate such as special tool MB 9e60 or its equivalent.
12. Press the toothed wheel off the axle shaft.
To install: 13. Press the new toothed wheel onto the shaft
with the groove facing the axle shaft flange. 14. Install the axle shaft to the knuckle and fit the
companion flange in place.
15. Install the lock washer and a new self-lock-
ing nut on the axle shaft. Tighten the nut to 116-159
ft. Ibs. (160-220 Nm).
16. Swing the axle assembly into place and in-
stall the 3 nuts and bolts. Tighten each to 45 ft. Ibs.
(61 Nm).
17. Install the brake disc and caliper.
18. Install the wheel speed sensor. Always use a
new O-ring.
19. Connect the parking brake cable to the
caliper.
20. Install the wheel and tire; lower the vehicle to
the ground.
There is no special procedure to bleed the ABS
system. Proceed with the normal brake bleeding pro-
cedure located earlier in this section.

II-6 TROUBLESHOOTING
DIAGhUSTIC PROCEDURES
Gasoline Engines
1. Engine turns over, but wilt not start
a. Check fuel level in fuel tank, add fuel if empty.
b. Check battery condition and state of charge. If voltage and load test below specifica-
tion, charge or replace battery.
c. Check battery terminal and cable condition and tightness. Clean terminals and replace
damaged, worn or corroded cables.
d. Check fuel delivery system. If fuel is not reaching the fuel injectors, check for a loose
electrical connector or defective fuse, relay or fuel pump and replace as necessary.
e. Engine may have excessive wear or mechanical damage such as low cylinder cranking
pressure, a broken camshaft drive system, insufficient valve clearance or bent valves.
f. Check for fuel contamination such as water in the fuel. During winter months, the wa-
ter may freeze and cause a fuel restriction. Adding a fuel additive may help, however
the fuel system may require draining and purging with fresh fuel.
g. Check for ignition system failure. Check for loose or shorted wires or damaged igni-
tion system components. Check the spark plugs for excessive wear or incorrect elec-
trode gap. If the problem is worse in wet weather, check for shorts between the spark
plugs and the ignition coils.
h. Check the engine management system for a failed sensor or control module.
2. Engine does not turn over when attempting to start
a. Check the battery state of charge and condition. If the dash lights are not visible or
very dim when turning the ignition key on, the battery has either failed internally or
discharged, the battery cables are loose, excessively corroded or damaged, or the al-
ternator has failed or internally shorted, discharging the battery. Charge or replacethe
battery, clean or replace the battery cables, and check the alternator output.
b. Check the operation of the neutral safety switch. On automatic transmission vehicles,
try starting the vehicle in both Park and Neutral. On manual transmission vehicles, de-
press the clutch pedal and attempt to start. On some vehicles, these switches can be
adjusted. Make sure the switches or wire connectors are not loose or damaged. Re-
place or adjust the switches as necessary.
c. Check the starter motor, starter solenoid or relay, and starter motor cables and wires.
Check the ground from the engine to the chassis. Make sure the wires are not loose,
damaged, or corroded. If battery voltage is present at the starter relay, try using a re-
mote starter to start the vehicle for test purposes only. Replace any damaged or cor-
roded cables, in addition to replacing any failed components.
d. Check the engine for seizure. If the engine has not been started for a long period of
time, internal parts such as the rings may have rusted to the cylinder walls. The engine
may have suffered internal damage, or could be hydro-locked from ingesting water.
Remove the spark plugs and carefully attempt to rotate the engine using a suitable
breaker bar and socket on the crankshaft pulley. If the engine is resistant to moving, or
moves slightly and then binds, do not force the engine any further before determining
the problem.
3. Enpine stalls immediately when started
a. Check the ignition switch condition and operation. The electrical contacts in the run
position may be worn or damaged. Try restarting the engine with all electrical acces-
sories in the off position. Sometimes turning the key on an off will help in emergency
situations, however once the switch has shown signs of failure, it should be replaced
as soon as possible.
b. Check for loose, corroded, damaged or shorted wires for the ignition system and re-
pair or replace.
c. Check for manifold vacuum leaks or vacuum hose leakage and repair or replace parts
as necessary.
d. Measure the fuel pump delivery volume and pressure. Low fuel pump pressure can
also be noticed as a lack of power when accelerating. Make sure the fuel pump lines
are not restricted. The fuel pump output is not adjustable and requires fuel pump re-
placement to repair.
e. Check the engine fuel and ignition management system. Inspect the sensor wiring and
electrical connectors. A dirty, loose or damaged sensor or control module wire can
simulate a failed component.
f. Check the exhaust system for internal restrictions.
4. Starter motor spins, but does not engage
a. Check the starter motor for a seized or binding pinion gear.
b. Remove the flywheel inspection plate and check for a damaged ring gear.
5. Engine is difficult to start when Gold
a. Check the battery condition, battery state of charge and starter motor current draw. Re-
place the battery if marginal and the starter motor if the current draw is beyond specifi-
cation. b. Check the battery cable condition. Clean the battery terminals and replace corroded or
damaged cables.
c. Check the fuel system for proper operation. A fuel pump with insufficient fuel pressure
or clogged injectors should be replaced.
d. Check the engine’s tune-up status. Note the tune-up specifications and check for items
such as severely worn spark plugs; adjust or replace as needed. On vehicles with
manually adjusted valve clearances, check for tight valves and adjust to specification.
e. Check for a failed coolant temperature sensor, and replace if out of specification.
f. Check the operation of the engine management systems for fuel and ignition; repair or
replace failed components as necessary.
6. En#ine is ditticutt to start when hot
a. Check the air filter and air intake system. Replace the air filter if it is dirty or contami-
nated. Check the fresh air intake system for restrictions or blockage.
b. Check for loose or deteriorated engine grounds and clean, tighten or replace as
needed.
c. Check for needed maintenance. Inspect tune-up and service related items such as
spark plugs and engine oil condition, and check the operation of the engine fuel and
ignition management system.
Diesel Engines
1. Engine turns over but won’t start
a. Check engine starting procedure and restart engine.
b. Check the glow plug operation and repair or replace as necessary.
c. Check for air in the fuel system or fuel filter and bleed the air as necessary.
d. Check the fuel delivery system and repair or replace as necessary.
e. Check fuel level and add fuel as needed.
f. Check fuel quality. If the fuel is contaminated, drain and flush the fuel tank.
g. Check engine compression. If compression is below specification, the engine may
need to be renewed or replaced.
h. Check the injection pump timing and set to specification.
i. Check the injection pump condition and replace as necessary.
j. Check the fuel nozzle operation and condition or replace as necessary.
2. Engine does
hot turn over when attempting to start
a. Check the battery state of charge and condition. If the dash lights are not visible or
very dim when turning the ignition key on, the battery has either failed internally or
discharged, the battery cables are loose, excessively corroded or damaged, or the al-
ternator has failed or internally shorted, discharging the battery. Charge or replace the
battery, clean or replace the battery cables, and check the alternator output.
b. Check the operation of the neutral safety switch. On automatic transmission vehicles,
try starting the vehicle in both Park and Neutral. On manual transmission vehicles, de-
press the clutch pedal and attempt to start. On some vehicles, these switches can be
adjusted. Make sure the switches or wire connectors are not loose or damaged. Re-
place or adjust the switches as necessary.
c. Check the starter motor, starter solenoid or relay, and starter motor cables and wires.
Check the ground from the engine to the chassis. Make sure the wires are not loose,
damaged, or corroded. If battery voltage is present at the starter relay, try using a re-
mote starter to start the vehicle for test purposes only. Replace any damaged or cor-
roded cables, in addition to replacing any failed components.
d. Check the engine for seizure. If the engine has not been started for a long period of
time, internal parts such as the rings may have rusted to the cylinder walls. The engine
may have suffered internal damage, or could be hydro-locked from ingesting water.
Remove the injectors and carefully attempt to rotate the engine using a suitable
breaker bar and socket on the crankshaft pulley. If the engine is resistant to moving, or
moves slightly and then binds, do not force the engine any further before determining
the cause of the problem.
3. Engine stalls afier starting
a. Check for a restriction in the fuel return line or the return line check valve and repair as
necessary.
b. Check the glow plug operation for turning the glow plugs off too soon and repair as
necessary.
c. Check for incorrect injection pump timing and reset to specification.
d. Test the engine fuel pump and replace if the output is below specification.
e. Check for contaminated or incorrect fuel. Completely flush the fuel system and replace
with fresh fuel.
f. Test the engine’s compression for low compression. If below specification, mechanical
repairs are necessary to repair.
g. Check for air in the fuel. Check fuel tank fuel and fill as needed.
h. Check for a failed injection pump. Replace the pump, making sure to properly set the
pump timing.

TROUBLESHOOiNG 11-7
4. Starter motor spins, but does not engage
a. Check the starter motor for a seized or binding pinion gear.
b. Remove the flywheel inspection plate and check for a damaged ring gear.
Gasoline Engines
1. Engine runs poor/y, hesiiates
a. Check the engine ignition system operation and adjust if possible, or replace defective
parts.
b. Check for restricted fuel injectors and replace as necessary.
c. Check the fuel pump output and delivery. Inspect fuel lines for restrictions. If the fuel
pump pressure is below specification, replace the fuel pump.
d. Check the operation of the engine management system and repair as necessary.
2. Enfline lacks power
a. Check the engine’s tune-up status. Note the tune-up specifications and check for items
such as severely worn spark plugs; adjust or replace as needed. On vehicles with
manually adjusted valve clearances, check for tight valves and adjust to specification.
b. Check the air filter and air intake system. Replace the air filter if it is dirty or contami-
nated. Check the fresh air intake system for restrictions or blockage.
c. Check the operation of the engine fuel and ignition management systems. Check the
sensor operation and wiring. Check for low fuel pump pressure and repair or replace
components as necessary.
d. Check the throttle linkage adjustments. Check to make sure the linkage is fully open-
ing the throttle. Replace any worn or defective bushings or linkages.
e. Check for a restricted exhaust system. Check for bent or crimped exhaust pipes, or in-
ternally restricted mufflers or catalytic converters. Compare inlet and outlet tempera-
tures for the converter or muffler. If the inlet is hot, but outlet cold, the component is
restricted.
f. Check for a loose or defective knock sensor. A loose, improperly torqued or defective
knock sensor will decrease spark advance and reduce power. Replace defective knock
sensors and install using the recommended torque specification.
g. Check for engine mechanical conditions such as low compression, worn piston rings,
worn valves, worn camshafts and related parts. An engine which has severe mechani-
cal wear, or has suffered internal mechanical damage must be rebuilt or replaced to re-
store lost power.
h. Check the engine oil level for being overfilled. Adjust the engine’s oil level, or change
the engine oil and filter, and top off to the correct level.
i. Check for an intake manifold or vacuum hose leak. Replace leaking gaskets or worn
vacuum hoses.
j. Check for dragging brakes and replace or repair as necessary.
k. Check tire air pressure and tire wear. Adjust the pressure to the recommended set-
tings. Check the tire wear for possible alignment problems causing increased rolling
resistance, decreased acceleration and increased fuel usage.
I. Check the octane rating of the fuel used during refilling, and use a higher octane rated
fuel.
3. Poor fuel economy
a. Inspect the air filter and check for any air restrictions going into the air filter housing.
Replace the air filter if it is dirty or contaminated.
b. Check the engine for tune-up and related adjustments. Replace worn ignition parts,
check the engine ignition timing and fuel mixture, and set to specifications if possible.
c. Check the tire size, tire wear, alignment and tire pressure. Large tires create more
rolling resistance, smaller tires require more engine speed to maintain a vehicle’s road
speed. Excessive tire wear can be caused by incorrect tire pressure, incorrect wheel
alignment or a suspension problem. All of these conditions create increased rolling
resistance, causing the engine to work harder to accelerate and maintain a vehicle’s
speed.
d. Inspect the brakes for binding or excessive drag. A sticking brake caliper, overly ad-
justed brake shoe, broken brake shoe return spring, or binding parking brake cable or
linkage can create a significant drag, brake wear and loss of fuel economy. Check the
brake system operation and repair as necessary.
4. Engine runs on (diesels) when turned off
a. Check for idle speed set too high and readjust to specification.
b. Check the operation of the idle control valve, and replace if defective.
c. Check the ignition timing and adjust to recommended settings.
Check for defective
sensors or related components and replace if defective.
d. Check for a vacuum leak at the intake manifold or vacuum hose
and replace defective
gaskets or hoses.
e. Check the engine for excessive carbon build-up in the combustion chamber. Use a
recommended decarbonizing fuel additive or disassemble the cylinder head to remove
the carbon.
f. Check the operation of the engine fuel management system and replace defective sen-
sors or control units.
g. Check the engine operating temperature for overheating and repair as necessary. 5. Engine knocks and pinfls during heavy accele/ation, and on steep hills
a. Check the octane rating of the fuel used during refilling, and use a higher octane rated
fuel.
b. Check the ignition timing and adjust to recommended settings. Check for defective
sensors or related components and replace if defective.
c. Check the engine for excessive carbon build-up in the combustion chamber. Use a
recommended decarbonizing fuel additive or disassemble the cylinder head to remove
the carbon.
d. Check the spark plugs for the correct type, electrode gap and heat range. Replace worn
or damaged spark plugs. For severe or continuous high speed use, install a spark plug
that is one heat range colder.
e. Check the operation of the engine fuel management system and replace defective sen-
sors or control units.
f. Check for a restricted exhaust system. Check for bent or crimped exhaust pipes, or in-
ternally restricted mufflers or catalytic converters. Compare inlet and outlet tempera-
tures for the converter or muffler. If the inlet is hot, but outlet cold, the component is
restricted.
6. Engine atxelerates, but vehicle does not gain speed
a. On manual transmission vehicles, check for causes of a slipping clutch. Refer to the
clutch troubleshooting section for additional information.
b. On automatic transmission vehicles, check for a slipping transmission” Check the
transmission fluid level and condition. If the fluid level is too high, adjust to the cor-
rect level. If the fluid level is low, top off using the recommended fluid type. If the fluid
exhibits a burning odor, the transmission has been slipping internally. Changing the
fluid and filter may help temporarily, however in this situation a transmission may re-
quire overhauling to ensure long-term reliability.
Diesel Engines
1. Engine runs pOOr!y a. Check the injection pump timing and adjust to specification.
b. Check for air in the fuel lines or leaks, and bleed the air from the fuel system.
c. Check the fuel filter, fuel feed and return lines for a restriction and repair as necessary.
d. Check the fuel for contamination, drain and flush the fuel tank and replenish with fresh
fuel.
2. Enfline lacks power
a. Inspect the air intake system and air filter for restrictions and, if necessary, replace the
air filter.
b. Verify the injection pump timing and reset if out of specification.
c. Check the exhaust for an internal restriction and replace failed parts.
d. Check for a restricted fuel filter and, if restricted, replace the filter.
e. Inspect the fuel filler cap vent. When removing the filler cap, listen for excessive hiss-
ing noises indicating a blockage in the fuel filler cap vents, If the filler cap vents are
blocked, replace the cap.
f. Check the fuel system for restrictions and repair as necessary.
g. Check for low engine compression and inspect for external leakage at the glow plugs
or nozzles. If no external leakage is noted, repair or replace the engine.
ENGINE PERFORMANCE TROUBLESHOOTING HINTS When troubleshooting an engine running or performance condition, the mechanical
condition of the engine should be determined before lengthy troubleshooting procedures
are performed.
The engine fuel management systems in fuel injected vehicles rely on electronic sen-
sors to provide information to the engine control unit for precise fuel metering. Unlike
carburetors, which use the incoming air speed to draw fuel through the fuel metering jets
in order to provide a proper fuel-to-air ratio, a fuel injection system provides a specific
amount of fuel which is introduced by the fuel injectors into the intake manifold or intake
port, based on the information provided by electronic sensors.
The sensors monitor the engine’s operating temperature, ambient temperature and the
amount of air entering the engine, engine speed and throttle position to provide informa-
tion to the engine control unit, which, in turn, operates the fuel injectors by electrical
pulses. The sensors provide information to the engine control unit using low voltage
electrical signals. As a result, an unplugged sensor or a poor electrical contact could
cause a poor running condition similar to a failed sensor.
When troubleshooting a fuel related engine condition on fuel injected vehicles, care-
fully inspect the wiring and electrical connectors to the related components. Make sure
the electrical connectors are fully connected, clean and not physically damaged. If neces-
sary, clean the electrical contacts using electrical contact cleaner. The use of cleaning
agents not specifically designed for electrical contacts should not be used, as they could
leave a surface film or damage the insulation of the wiring.
The engine electrical system provides the necessary electrical power to operate the ve-
hicle’s electrical accessories, electronic control units and sensors. Because engine man-
agement systems are sensitive to voltage changes, an alternator which over or under-
charges could cause engine running problems or component failure. Most alternators
utilize internal voltage regulators which cannot be adjusted and must be replaced indi-
vidually or as a unit with the alternator.

11-8 TROUBLESHOOTING
Ignition systems may be controlled by, or linked to, the engine fuel management sys-
tem. Similar to the fuel injection system, these ignition systems rely on electronic sen-
sors for information to determine the optimum ignition timing for a given engine speed
and load. Some ignition systems no longer allow the ignition timing to be adjusted.
Feedback from low voltage electrical sensors provide information to the control unit to
determine the amount of ignition advance. On these systems, if a failure occurs the failed
component must be replaced. Before replacing suspected failed electrical components,
carefully inspect the wiring and electrical connectors to the related components. Make
sure the electrical connectors are fully connected, clean and not physically damaged. If
necessary, clean the electrical contacts using electrical contact cleaner. The use of clean-
ing agents not specifically designed for electrical contacts should be avoided, as they
could leave a surface film or damage the insulation of the wiring.
1. Engine makes a knocking or pinging noise when accelerating
a. Check the octane rating of the fuel being used. Depending on the type of driving or
driving conditions, it may be necessary to use a higher octane fuel.
b. Verify the ignition system settings and operation. Improperly adjusted ignition timing
or a failed component, such as a knock sensor, may cause the ignition timing to ad-
vance excessively or prematurely. Check the ignition system operation and adjust, or
replace components as needed.
c. Check the spark plug gap, heat range and condition. If the vehicle is operated in se-
vere operating conditions or at continuous high speeds, use a colder heat range spark
plug. Adjust the spark plug gap to the manufacturer’s recommended specification and
replace worn or damaged spark plugs.
2. Sfarter motor grinds when used
a. Examine the starter pinion gear and the engine ring gear for damage, and replace dam-
aged parts.
b. Check the starter mounting bolts and housing. If the housing is cracked or damaged
replace the starter motor and check the mounting bolts for tightness.
3. Engine makes a screeching noise
a. Check the accessory drive belts for looseness and adjust as necessary.
b. Check the accessory drive belt tensioners for seizing or excessive bearing noises and
replace if loose, binding, or excessively noisy.
c. Check for a seizing water pump. The pump may not be leaking; however, the bearing
may be faulty or the impeller loose and jammed. Replace the water pump.
4. Engine makes a growling noise
a. Check for a loose or failing water pump. Replace the pump and engine coolant.
b. Check the accessory drive belt tensioners for excessive bearing noises and replace if
loose or excessively noisy.
5. Engine makes a ticking or tapping noise
a. On vehicles with hydraulic lash adjusters, check for low or dirty engine oil and top off
or replace the engine oil and filter.
b. On vehicles with hydraulic lash adjusters, check for collapsed lifters and replace failed
components.
c. On vehicles with hydraulic lash adjusters, check for low oil pressure caused by a re-
stricted oil filter, worn engine oil pump, or oil pressure relief valve.
d. On vehicles with manually adjusted valves, check for excessive valve clearance or
worn valve train parts. Adjust the valves to specification or replace worn and defective
parts.
e. Check for a loose or improperly tensioned timing belt or timing chain and adjust or re-
place parts as necessary.
f. Check for a bent or sticking exhaust or intake valve. Remove the engine cylinder head
to access and replace.
6. Engine makes a heavy knocking noise
a. Check for a loose crankshaft pulley or flywheel; replace and torque the mounting
bolt(s) to specification.
b. Check for a bent connecting rod caused by a hydro-lock condition. Engine disassem-
bly is necessary to inspect for damaged and needed replacement parts.
c. Check for excessive engine rod bearing wear or damage. This condition is also asso-
ciated with low engine oil pressure and will require engine disassembly to inspect for
damaged and needed replacement parts,
7. Vehicle has a fuel odor when driven ’ a. Check the fuel gauge level. If the fuel gauge registers full, it is possible that the odor is
caused by being filled beyond capacity, or some spillage occurred during refueling.
The odor should clear after driving an hour, or twenty miles, allowing the vapor canis-
ter to purge.
b. Check the fuel filler cap for looseness or seepage. Check the cap tightness and, if
loose, properly secure. If seepage is noted, replace the filler cap.
c. Check for loose hose clamps, cracked or damaged fuel delivery and return lines, or
leaking components or seals, and replace or repair as necessary. d. Check the vehicle’s fuel economy. If fuel consumption has increased due to a failed
component, or if the fuel is not properly ignited due to an ignition related failure, the
catalytic converter may become contaminated. This condition may also trigger the
check engine warning light. Check the spark plugs for a dark, rich condition or verify
the condition by testing the vehicle’s emissions. Replace fuel fouled spark plugs, and
test and replace failed components as necessary.
5. Vehicle has a rotten egg odor when driven
a. Check for a leaking intake gasket or vacuum leak causing a lean running condition. A
lean mixture may result in increased exhaust temperatures, causing the catalytic con-
verter to run hotter than normal. This condition may also trigger the check engine
warning light. Check and repair the vacuum leaks as necessary.
b. Check the vehicle’s alternator and battery condition. If the alternator is overcharging,
the battery electrolyte can be boiled from the battery, and the battery casing may begin
to crack, swell or bulge, damaging or shorting the battery internally. If this has oc-
curred, neutralize the battery mounting area with a suitable baking soda and water
mixture or equivalent, and replace the alternator or voltage regulator. Inspect, service,
and load test the battery, and replace if necessary.
9. Vehicle has a sweet odor when driven
a. Check for an engine coolant leak caused by a seeping radiator cap, loose hose clamp,
weeping cooling system seal, gasket or cooling system hose and replace or repair as
needed.
b. Check for a coolant leak from the radiator, coolant reservoir, heater control valve or
under the dashboard from the heater core, and replace the failed part as necessary.
c. Check the engine’s exhaust for white smoke in addition to a sweet odor. The presence
of white, steamy smoke with a sweet odor indicates coolant leaking into the combus-
tion chamber. Possible causes include a failed head gasket, cracked engine block or
cylinder head. Other symptoms of this condition include a white paste build-up on the
inside of the oil filler cap, and softened, deformed or bulging radiator hoses.
19. Engine vibraies when idling
a. Check for loose, collapsed, or damaged engine or transmission mounts and repair or
replace as necessary.
b. Check for loose or damaged engine covers or shields and secure or replace as neces-
sary.
11. Engine vibrates during acceleration
a. Check for missing, loose or damaged exhaust system hangers and mounts; replace or
repair as necessary.
b. Check the exhaust system routing and fit for adequate clearance or potential rubbing;
repair or adjust as necessary.
7. Battery goes dead while driving
a. Check the battery condition. Replace the battery if the battery will not hold a charge or
fails a battery load test. If the battery loses fluid while driving, check for an overcharg-
ing condition. If the alternator is overcharging, replace the alternator or voltage regula-
tor. (A voltage regulator is typically built into the alternator, necessitating alternator re-
placement or overhaul.)
b. Check the battery cable condition. Clean or replace corroded cables and clean the bat-
tery terminals.
c. Check the alternator and voltage regulator operation. If the charging system is over or
undercharging, replace the alternator or voltage regulator, or both.
d. Inspect the wiring and wire connectors at the alternator for looseness, a missing .
ground or defective terminal, and repair as necessary.
e. Inspect the alternator drive belt tension, tensioners and condition. Properly tension the
drive belt, replace weak or broken tensioners, and replace the drive belt if worn or
cracked.
2. Battery goes dead overnight
a. Check the battery condition. Replace the battery if the battery will not hold a charge or
fails a battery load test.
b. Check for a voltage draw, such as a trunk light, interior light or glove box light staying
on. Check light switch position and operation, and replace if defective.
c. Check the alternator for an internally failed diode, and replace the alternator if defec-
tive.
1. Engine overheats
a. Check the coolant level. Set the heater temperature to full hot and check for internal air
pockets, bleed the cooling system and inspect for leakage. Top off the cooling system
with the correct coolant mixture.
b. Pressure test the cooling system and radiator cap for leaks. Check for seepage caused
by loose hose clamps, failed coolant hoses, and cooling system components such as
the heater control valve, heater core, radiator, radiator cap, and water pump. Replace
defective parts and fill the cooling system with the recommended coolant mixture.