ignition DODGE TRUCK 1993 Service Repair Manual

0 - 6
LUBRICATION
AND
MAINTENANCE
GASOLINE ENGINE MAINTENANCE SCHEDULE

HEAVY
DUTY
CYCLE

Inspection and service is also necessary anytime
a
malfunction is observed or suspected.
When both
time
and mileage
are
Miles (Thousand)

shewn,
follow
the
interval

which occurs first. Kilometers (Thousand) 6
12 18 24
30 36 42 48 54
60 66 72

78
82V2
84 90
96
102 108
When both
time
and mileage
are
Miles (Thousand)

shewn,
follow
the
interval

which occurs first. Kilometers (Thousand) 9.6 19 29
38 48 58 67 77
85 96 106 116
125 132
135
145
154 164
174

Coolant
Condition, Coolant
Hoses/Clamps
X
X X X
X X X X
X X X X
X X X
X X X

Exhaust
System
—
Check
X X X X X X X X X X X
X X X X X
X X

Oil
—
Change
(6
Months)
X X X X X X X
X X

X
X
X

X X X

X X
X

Oil
Filter
—
Change (2nd
Oil
Change)
X X X X
X X
X X
X

Drive Belt Tension
—
Inspect
&
Adjust
X' X
X1

X X' X

Drive Belts (V-Type)
—
Replace
X

Air
Filter/Air
Pump
Air
Filter
—
Replace
X X X
X

Crankcase
Inlet
Air
Filter
(6 &
8
Cyl.
Eng.
Only)
—
Clean
X X
X X

Spark
Plug
—
Replace
X X X

Fuel
Filter
—
Replace as necessary

Coolant
—
Flush/Replace
(36
months)
& 24
months/48
000 km

(30,000
miles)
thereafter
X
EGR
Valve
&
Tube
—
Replace X2

EGR
Tube
—
Clean Passengers
X2
PCV
Valve
—
Replace X2

Vacuum
Emission
Components
—
Replace
X

Ignition Timing
—
Adjust
to
Specs,
as necessary X
Ignition Cables, Distributor Cap
&
Rotor
—
Replace
X

Manifold Heat Control Valve
—
Lubricate
X

Battery
—
Replace X

Oxygen
Sensor
—
Replace
X2

1 For California vehicles, this maintenance is recommended
by
Chrysler Motors
to the
owner but, is not
required
to
maintain the
warranty
on the
air
pump drive
belt.

2 Requires
Emission
Maintenance Reminder Light.
If
so equipped, these parts
are to be
replaced
at the
indicated mileage,
or
when the
emissions
maintenance reminded light remains on continuously
with
the key in the
"on" position, whichever occurs first.
J9100-20

DIESEL
ENGINE
MAINTENANCE
SCHEDULE
HEAVY
DUTY
CYCLE
Inspection
and
service
is
also
necessary
any
time
a
malfunction
is
observed
or
suspected.

Iff both
time
and distance Miles (Thousand)
are listed, use the
interval

that
ends
first. Kilometers (Thousand) 6
12
18 24
30 36 42

4S
54
60 66
72 78
84 90 96
102 108
Iff both
time
and distance Miles (Thousand)
are listed, use the
interval

that
ends
first. Kilometers (Thousand) 9,6 19
29
38 48 58 67

77

85 96 106
116 125 135 145 154
164 174

Coolant
Condition, Coolant
Hoses/Clamps
(12 months)

Coolant
Flush/Replace (36 months) & 24 months/
48 000 km
(30,000
miles)
thereafter
O

Oil—Change
(6 months)
X X X
X X X
X X X X X
X X X X X X
X

Oil Filter—Replace (Every Oil Change)
X X X
X X X
X X
X X X
X
X X X X
X X

Drive Belts—Replace
As
Necessary
X X
X X X X

Air Filter—Replace
X X
X X

Air Filter—Clean (California Only) e

®

• •
Air
Filter
Canister—Clean
o o o
o

Fuel Filter—Service When Necessary

Injection
Pump
Timing & Engine Idle Speed—

Check
& Adjust
©

• 9 • • •
Underhood Rubber/Plastic Components—Inspect/Replace • • • • •

X
— All vehicles
O
— All
vehicles
except
California.
Recommended
for
California.
•
— California only.
Recommended
for all vehicles.

0 - 12
LUBRICATION
AND
MAINTENANCE

• A vehicle equipped with SAE approved sling-type
towing equipment can be used (Fig. 10). However,
many vehicles are equipped with air dams, spoilers, and/or ground effect panels. In this case a wheel-lift
towing vehicle or a flat-bed hauling vehicle is recom­ mended (Fig. 10). If a flat bed device is used, the ap­
proach angle should not exceed 15 degrees.
GROUND CLEARANCE The lifted wheels of the disabled vehicle should be
a minimum of 10 cm (4 in.) off the ground. Make
sure there is enough clearance at the opposite end.
This is critical when towing over rough terrain. If necessary, the rear ground clearance can be in­creased by removing the wheels from the lifted end
and then towing with the lifted end closer to the
ground. If the rear wheels are removed, secure the
brake drums. A 20 cm (8 in.) ground clearance must
be maintained between brake drums or rotors and the ground.
SAFETY PRECAUTIONS The following safety precautions must be consid­
ered when preparing for and during a vehicle towing operation:
• Remove exhaust pipe tips that interfere with the
tow sling and crossbar • Padding should be placed between the tow sling/
crossbar and any painted surfaces
• If the vehicle is damaged, secure the loose and pro­
truding parts
• Always use a safety chain system that is indepen­ dent of the lifting and towing equipment
• When placing tow hooks on the rear axle, position them so they do not damage the brake tubing or
hoses
• Do not allow any of the towing equipment to con­
tact the fuel tank
• Do not tow the vehicle by connecting to the front
or rear shock absorbers
• The operator should not go under a vehicle while
it is lifted by the towing equipment. The vehicle
should first be supported by safety stands
• Do not allow passengers in a vehicle being towed
• Observe all state and local laws involving warning signals, night illumination, speed, etc.
• Do not exceed a towing speed of 48 km/h (30 mph)
• Avoid towing distances of more than 24 km (15
miles) whenever possible • Do not attach tow chains or a tow sling to a
bumper, the steering linkage, the universal joints, or a drive shaft
REAR-END RAISED TOWING It is recommended that the rear-end raised towing
method be used. Vehicles can be towed with the front
wheels on the ground for extended distances at speeds not exceeding 48 km/h (30 mph) (Fig. 11). (1) Attach the J-hooks around the axle shaft tubes
outboard of the rear springs. (2) Position and center the sling under and for­
ward of the rear bumper. (3) Attach safety chains (with pads) at each end of
the rear bumper.
(4) Turn the ignition switch to the OFF position to
unlock the steering wheel. (5) Clamp the steering wheel with the front wheels
in the straight ahead position.

CAUTION:
Do not use the steering
column
lock
to

secure
front
wheel
in the straight-ahead
position.

(6) Shift the transmission to NEUTRAL.

POSITION CENTER BAR FORWARD
OF
BUMPER
-
/
J-HOOKS OUTBOARD
OF
SPRINGS
RN967A

Fig. 11 Rear-End
Raised
Towing
FRONT'END RAISED TOWING If a vehicle cannot be towed from the rear, the
front-end raised towing method normally can be
used (Fig. 12). (1) Center the sling with the bumper and position
it at the frame front crossmember.

CAUTION:
Use tow
chains
with
J-hooks
for
con­
necting
to the
disabled
vehicle's
lower
suspension
arms.
Never use
T-hooks.

(2) Route the J-hooks and tow chains over the
steering linkage outboard of the coil spring.
(3) Attach the J-hooks to the outer end of the
lower suspension arms.
(4) Raise the vehicle.
(5.) Attach the safety chains to the disabled vehicle
at the frame rails.
Vehicles equipped with a MANUAL TRANSMIS­
SION can be towed with the rear wheels on the

0 - 14
LUBRICATION
AND
MAINTENANCE

•
ENGINE
MAINTENANCE

INDEX

page
Air
Injection
Systems/Air Pump
. 17

Air-Conditioner
Compressor
21
Battery
19

Cooling System
15

Crankcase
Ventilation
System
17
Diesel Engine
Air Filter
Canister
17

Drive Belts
20
Engine
Air
Cleaner
Filter
Element
16

Engine Break-In
14

Engine
Oil 14

Engine
Oil
Change
and Filter
Replacement
15

Exhaust Gas
Recirculation
(EGR) System
...... 19
page
Exhaust
Manifold
Heat
Control
Valve
. 17
Exhaust System
, 21

Fuel System
18

Hoses
and
Fittings
16
Ignition
Cables,
Distributor
Cap and
Rotor
...... 19

Ignition
Timing
. 19

Oxygen
(02)
Sensor
19
Rubber/Plastic Components
20

Spark Plugs
. 19

Throttle
Control
Linkage
18

Vacuum Operated, Emission
Control
Components
19

ENGINE BREAK-IN
After first starting a new engine, allow it to idle
for 15 seconds before shifting into a drive gear. Also:
• Drive the vehicle at varying speeds less than 88
km/h (55 mph) for the first 480 km (300 miles).
• Avoid fast acceleration and sudden stops.
• Do not drive at full-throttle for extended periods of
time
• Do not drive at constant speeds
• Do not idle the engine excessively A special break-in engine oil is not required. The
original engine oil installed is a high quality lubri­
cant. New engines tend to consume more fuel and oil un­
til after the break-in period has ended.

ENGINE
OIL SPECIFICATIONS

API SERWICE
GRADE
Use an engine oil that conforms to API Service
Grade S5 SG/CD or SG/CE. MOPAR®provides engine
oils that conform to all of these service grades.

SULFATED ASH—DIESEL ENGINES
Oils that contain an excessive amount of sulfated
ash can cause deposits to develop on Diesel engine
valves. These deposits can result in valve wear.

SAE
WISC0SITY
An SAE viscosity grade is used to specify the vis­
cosity of engine oil. SAE 30 specifies a single viscos­
ity engine oil.
Engine oils also have multiple viscosities. 10W-30

<
5W-30

1
1 1

F
-20 0 10 20 32 60 80 100

C
-29 -18 -12 -7 0 16 27 38
ANTICIPATED
TEMPERATURE RANGE BEFORE
NEXT
OIL
CHANGE
J9000-39

Fig.
1 Temperature/Engine Oil Viscosity—Gasoline
Engines

-12°C
-18°C 10°F
0°F- 15W-40

-23°c(^-10eF

I
10W-30
WITH
WITHOUT
BLOCK HEATER
BLOCK
SYNTHETIC
OIL

HEATER
10W-30 5W-30

J9100-29

Fig.
2 Temperature/Engine Oil Viscosity—Diesel
Engines

ENERGY
G0NSERWING
OIL
An Energy Conserving type oil is recommended for
gasoline engines. They are designated as either EN­
ERGY CONSERVING or ENERGY CONSERVING

II.
OIL
LEVEL
INDICATOR (DIPSTICK)

GASOLINE ENGINES
The engine oil indicator is located at the right
front of the engine.

•

LUBRICATION
AND
MAINTENANCE
0 - 19 ETBE— This fuel is a mixture of unleaded gasoline
and up to 17 percent ETBE (Ethyl Tertiary Butyl

Ether).
Unleaded gasoline blended with ETBE is ac­ ceptable.
METHANOL—Do not use unleaded gasoline
blended with methanol. The use of this type of alco­ hol can result in engine performance and damage to
critical components. Engine problems that result
from the use of methanol possibly will not be covered by the new vehicle warranty.
Certain brands of unleaded gasoline contain a per­
centage of unidentified alcohol. These types of un­
leaded gasoline are not recommended.

ADDITIVES MIXED
WITH
GASOLINE
Use of fuel system cleaning additives should be
avoided. Many of these solutions could contain highly
active solvents. This type of solvent can be harmful
to the gasket and diaphragm material within the fuel system.

DIESEL
ENGINE FUEL REQUIREMENTS
All Diesel engines normally can use number 2D
Diesel fuel for most year-round operations. A fuel
conforming to ASTM Specification D-975 is recom­
mended. For extreme cold-weather operation (below
-18°C/0°F), or for prolonged cold-climate operation ei­
ther:
• Use No. ID fuel, or
• Add an equal quantity of kerosene to No. 2D fuel (a 50/50 mixture).
Both methods provide protection against fuel gel­
ling and waxing.
Diesel fuel seldom is without water contamination.
To help prevent fuel system malfunctions, drain all accumulated water from the separators periodically.

VACUUM OPERATED,
EMISSION
CONTROL
COMPONENTS

MAINTENANCE SCHEDULE
The following emission controls should be replaced
at the interval specified in the maintenance sched­

ule:

• Bi-level purge check valves
• Delay valves
• Heated air temperature sensor (HATS)
• Air cleaner vacuum motors

EXHAUST
GAS RECIRCULATION (EGR)
SYSTEM

MAINTENANCE SCHEDULE
Replace the EGR valve and tube, and clean the
passages at the interval specified in maintenance schedule. If necessary, refer to Group 25—Emission
Control Systems for additional information.
OXYGEN
(02)
SENSOR

MAINTENANCE SCHEDULE
Replace the 02 sensor at the interval specified in
maintenance schedule.

IGNITION
CABLES,
DISTRIBUTOR CAP AND

ROTOR

MAINTENANCE SCHEDULE
Replace the ignition cables, distributor cap, and ro­
tor at the interval specified in maintenance schedule.
Inspect the distributor for excessive wear and re­
place, as necessary. Refer to Group 8D—Ignition Sys­
tems for additional information.

IGNITION TIMING
MAINTENANCE SCHEDULE
Test and adjust, if necessary, the ignition timing at
the interval specified in maintenance schedule. Refer
to the specifications listed on the engine Emission Control Information label. Refer to Group 8D—Igni­
tion Systems and to Group 25—Emission Control Systems for additional service information.

SPARK
PLUGS MAINTENANCE SCHEDULE
Replace the spark plugs at the interval specified in
maintenance schedule. Refer to the Spark Plugs
chart below and to Group 8D—Ignition Systems for additional service information.

SPARK
PLUGS
ENGINE
SPARK

PLUG
SPARK

PLUG
GAP
TORQUE

3.9L
5.2L
5.9L
RN12YC

RN12YC

RN12YC
0.9 mm
(0.035
in.)
0.9 mm
(0.035
in.)
0.9 mm
(0.035
in.) 41 N*m (30 ft. lb.)
41 NVn (30 ft. lb.)
41 N*m (30 ft. lb.)

J9100-17

BATTERY

MAINTENANCE SCHEDULE
Replace battery at interval specified in mainte­
nance schedule.

•

FRONT
SUSPENSION
AND
AXLE
2 - 5 (4) Front wheels for excessive radial, lateral
runout and unbalance. Refer to Group 22, Wheels and Tires for diagnosis information.
(5) Suspension components for wear and noise. Check
components for correct torque. Refer to Groups 2 and 3, Suspension and Axle for additional information.

WHEEL
ALIGNMENT
MEASUREMENTS/ADJUSTMENTS
The front wheel alignment positions must be set to
the specified limits. This will prevent abnormal tire
tread wear. The equipment manufacturer's recommenda­
tions for use of their
equipment
should always
be followed. All
damaged
front suspension sys­
tem components
should
be replaced. Do not at­ tempt to straighten any
bent
component.

CAMBER AND CASTER-2WD VEHICLES Camber and caster angle adjustments involve repo­
sitioning the upper suspension arm cam adjustment
bolts (Fig. 2). Alignment adjustments are accom­
plished by loosening the nuts and changing the posi­
tion of the cam bolt.
(1) Remove all foreign material from the adjust­
ment bolt threads.
(2) Record the camber and caster measurements
before loosening the adjustment bolt nuts.
(3) The camber angle should be adjusted as near as
possible to the preferred angle. The caster should be
the same at both sides of the vehicle. Refer to the Specifications chart.
CAMBER AND CASTER—4WD VEHICLES For 4WD vehicles, the correct wheel camber (verti­
cal tilt) angle is factory preset at zero degree (0°).
Camber cannot be altered by adjustment.
CAUTION: Do not attempt to
adjust
the
camber
an­
gle by
heating
or bending the axle or any
suspen­

sion
component. If camber angle is
incorrect,
the
component(s)
causing
an
incorrect
angle must be replaced.
(1) It is important that the camber (vertical tilt)
angle be the same for both front wheels.
(2) The camber angle should be measured with ac­
curate wheel alignment equipment. The acceptable
range is -1° to +1°. Refer to the Specifications chart.
Road test the vehicle and observe the steering
wheel return-to-center position. Before road testing,
check
and
correct
the tire
inflation pressures. Inflate
both
of the front tires
with exactly the
same
pressure.
During the road test, make vehicle turns to both
the left and right. If the steering wheel returns to­
ward the center position unassisted, the caster angle is correct. However, if the steering wheel does not re­ turn toward the center position unassisted, an incor­
rect caster angle is probable.
(1) The caster angle is factory preset at positive
two degrees
(
+
2°).
The acceptable range is +1/2° to +
3
1/2°.
(2) The caster angle should be measured with ac­
curate wheel alignment equipment.
(3) Caster angle can be adjusted by installing ta­
pered shims between the front axle pads and the spring brackets. The caster angle should be adjusted
as near as possible to the preferred angle.
(4) Record the caster measurement before remov­
ing the original shims from the spring pads.
(5) The caster should be the same at both sides of
the vehicle. Refer to the Specifications chart.
RN1030

Fig.
2 Caster &
Camber
Adjustment Location—2WD
Vehicles

WHEEL TOE POSITION The wheel toe position adjustment should be the fi­
nal front wheel alignment adjustment. In all in­ stances, follow the equipment manufacturer's
recommended procedure.
(1) Secure the steering wheel with the front wheels
in the straight-ahead position. For vehicles equipped
with power steering, start the engine before straight­ ening the wheels.
With power steering, the engine should be op­
erating during the wheel toe position adjust­
ment.
(2) Loosen the tie rod adjustment sleeve clamp
bolts (Fig. 3).
(3) Adjust the wheel toe position by rotating the
tie rod adjustment sleeve (Fig. 3). Rotate each tie-rod end in the direction of
sleeve rotation during the adjustment (Fig. 3).
This will ensure that both tie-rod ends are at the center of their travel.
(4) If applicable, turn the ignition switch off.

3
- 28
REAR
SUSPENSION
AND
AXLE

•
SURE-GRIP
DIFFERENTIAL
SERVICE

GENERAL
INFORMATION
The Sure-Grip differential
is an
option available
in

the
8 1/4 and 9 1/4
inch rear axles
(Fig. 1).
EXCITER
RING RING

GEAR
DIFFERENTIAL

CASE

BEARING BEARING

J9003-119
Fig.
1
Sure-Grip
Differential

With
the
exception
of the
Sure-Grip differential

case,
all the
axle components
are
identical
to the

standard axle.
The
Sure-Grip
has a
two-piece differ­
ential case.
The
case
is
completely interchangeable
with
a
standard differential case
(Fig. 2).
Sure-Grip differential removal
and
installation
is
same
as
stan­
dard differential.
DIFFERENTIAL

CASE

PINION
GEAR

COIL SPRING LUBRICATION
WELL
SIDE
GEAR

CLUTCH

LUBRICATION
GROOVES

J9003-120

Fig.
2
Sure-Grip
Differential
Components
The action
of a
standard differential will allow
the

rear wheels
to
rotate
at
different speeds when
the ve­

hicle
is
turning. This differential will divide
the en­
gine torque equally between them. This
is a
desirable
and
normal function
of a
differential.
A

Sure-Grip differential transfers additional engine
torque
to the
rear wheel that
has the
better traction surface.
The
Sure-Grip differential allows
the
driving
wheel with better traction
to
develop more driving
torque than
the
other wheel.
The
Sure-Grip
is not a
locking type differential.
IDENTIFICATION Raise both rear wheels
off the
surface
and
rotate
them.
If
both rear wheels rotate
in the
same direc­
tion,
the
vehicle
is
equipped with
a
Sure-Grip differ­ ential. Another method
of
identification
is by

removing
the
housing cover fill hole plug. Examine (with
a
flashlight)
the
differential case components
through
the
lubricant fill hole.
SERVICE INFORMATION When Sure-Grip differential service
is
necessary,
both rear wheels must
be
raised
off the
surface
so
they
are
free
to
rotate.
A Sure-Grip differential case
is not
repairable.
If defective,
it
must
be
replaced
as a
complete
unit only.
Do not
attempt
to
disassemble
and re­

pair
the
case components.
Follow
the
same procedure outlined under Stan­
dard Differential
for
Removal
and
Installation.
DIFFERENTIAL TEST

CAUTION:
Whenever
a
rear axle
is
being
serviced,
RAISE
BOTH
REAR
WHEELS
off the
surface.
A Sure-Grip differential
can be
tested without
re­

moving
the
differential case from
the
housing.
(1) Position
the
vehicle
on a
hoist with
the
ignition

OFF.
Put the
transmission selector lever
in
PARK
(automatic transmission)
or in
first gear (manual
transmission).
(2) Attempt
to
manually rotate each rear wheel.
(3)
If
difficult
to
manually rotate either wheel,
the

Sure-Grip differential
is
functioning normally.
If

easy,
the
differential
is not
functioning normally
and
should
be
replaced.
A Sure-Grip differential case
is not
repairable.
If defective,
it
must
be
replaced
as a
complete
unit only.
Do not
attempt
to
disassemble
and re­

pair
the
case components.
DIFFERENTIAL NOISE Noise complaints involving
a
Sure-Grip should
be

evaluated
to
determine
the
source
of the
noise.
If a

noise occurs while
the
vehicle
is
turning,
the
proba­
ble cause
is
incorrect
or
insufficient gear lubricant. The drain
and
clean procedure should
be
used
for

possible elimination
of the
noise before replacing
the
differential.

5
- 6
BRAKES

• (c) On diesel models, vacuum pump hose or
pump component may have malfunctioned. Check
pump output with vacuum gauge and repair as necessary. Refer to service procedures in Power
Booster/Vacuum Pump section.
(6) Rebuild booster vacuum reserve as follows: Re­
lease brake pedal. Increase engine speed to 1500
rpm, close throttle and immediately turn off ignition. (7) Wait a minimum of 90 seconds and try brake ac­
tion again. Booster should provide two or more vacuum assisted pedal applications. If vacuum assist is not pro­
vided, perform booster and check valve vacuum tests.
Also check vacuum output on diesel models.

POWER
BOOSTER
CHECK
VALVE
TEST
(1) Disconnect vacuum hose from check valve.
(2) Remove check valve and valve seal from
booster (Fig. 1). (3) Hand operated vacuum pump can be used for
test (Fig. 2). (4) Apply 15-20 inches (50-67 kPa) vacuum at
large end of check valve (Fig. 1). (5) Vacuum should hold steady. If gauge on pump
indicates any vacuum loss, valve is faulty and must
be replaced.
BOOSTER

CHECK
VALVE
APPLY
TEST
\
VACUUM
HERE

Fig.
1
Vacuum
Check
Vaive
And
Seal
J9005-80

Fig.
2 Typical
Hand
Operated
Vacuum
Pump

POWER
BOOSTER
VACUUM
TEST
(1) Connect a vacuum gauge to the booster check
valve with a short length of hose and a T-fitting (Fig.

3).
(2) Start and run engine at idle speed for one
minute.
(3) Clamp hose shut between vacuum source and
check valve (Fig. 3).
(4) Stop engine and observe vacuum gauge.
(5) If vacuum drops more than one inch vacuum
(33 millibars) within 15 seconds, either booster dia­
phragm or check valve are faulty.
SHORT

CONNECTING
CHECK

VACUUM
GAUGE

J9005-81
Fig.
3
Booster
Vacuum
Test
Connections

TESTING
DIESEL
ENGINE
VACUUM
PUMP
OUTPUT
On models with a Cummins turbo diesel engine, a
low vacuum condition in the brake booster will cause
the brake warning light to illuminate. The following test checks output and condition of the
vacuum pump and interconnecting hoses. However, a
more comprehensive testing procedure is provided in
the Power Brake Booster-Brake Pedal-Vacuum Pump section. Refer to the procedure for "Diagnosing A Low
Vacuum Condition" in that section. (1) Check pump vacuum and booster hoses and
connections. Make sure hoses are in good condition and securely attached. Run engine and check for vac­
uum leaks. Replace leaking hoses before proceeding. (2) Disconnect vacuum hose at booster and connect
vacuum gauge to hose end. (3) Run engine at curb idle speed and note vacuum
reading. Then run engine at 1/2 to 3/4 throttle and
note vacuum reading again. (4) Vacuum should range from 8.5 to 25 inches
vacuum at various throttle openings. Vacuum should
hold steady and not drop below 8.5 inches. (5) If vacuum output is OK, check booster and
check valve as described in this section. However, if
vacuum is low, or does not hold steady, vacuum
hoses or pump components are faulty.

5
- 60
BRAKES

Fig.
2
Antilock
Electronic Control
Module
RWAL
HYDRAULIC
VALVE
The hydraulic valve is a pressure controlling device
and is operated by the electronic module. The valve
controls fluid apply pressure to the rear brake units
during antilock mode braking (Fig. 3). The valve is
mounted on the driver side frame rail at the front of
the vehicle.
The valve contains an accumulator, an isolation
valve and a dump valve. The accumulator is operated
by fluid and spring pressure. The two valves are op­ erated by electrical solenoids. The solenoids are oper­
ated by the antilock control module.
The hydraulic valve components are inactive dur­
ing periods of normal braking effort. The valve com­
ponents are activated only when braking effort and rate of wheel slip and deceleration are high (antilock

mode).

During normal braking the valve allows free flow
of brake fluid to the rear brake units. In antilock
mode, the valve will decrease, hold or increase fluid
apply pressure as needed. •

CONNECTOR
J9005-99
Fig. 3 RWAL Hydraulic Valve
SPEED
SENSOR
AND EXCITER RING
A single pole, variable reluctance speed sensor is
used to transmit speed and rate of deceleration in­
puts to the control module (Fig. 4). The sensor is ac­
tuated by an exiter ring on the differential case.
The sensor is mounted at the top of the rear axle
housing directly over the gear-type exiter ring (Fig.
1).
The exciter ring is pressed onto the differential
case next to the ring gear.
The exciter ring is the sensor trigger mechanism.
As the ring rotates, the teeth on the ring will inter­
rupt the magnetic field around the sensor pole. The rate of interruption is converted into speed signals
which are transmitted to the control module.

Fig.
4
RWAL Speed Sensor

ANTILOCK INDICATOR LAMP The amber colored indicator lamp is located in the
instrument panel. The lamp alerts the driver if a sys­
tem fault occurs.
The antilock and brake warning lamps are both in
circuit with the electronic module. The module will
cuit with the module. The module contains a micro­
processor that operates the system and performs system diagnostic checks. Speed sensor inputs are continuously monitored
and interpreted by the module. The module deter­
mines wheel speed and rate of deceleration from
these inputs and activates the appropriate solenoid in the hydraulic valve when necessary.
The module microprocessor also contains a self test
program. The program is activated when the ignition switch is turned to the On position. In this mode, the
module checks indicator light operation, the system
electrical circuits and the pressure limiting valve so­
lenoids.
The brake warning and antilock indicator lamps
are illuminated for approximately two seconds dur­
ing the system self test cycle.

i - 62
BRAKES

•
Isolation/Dump
Valve Cycle Times
Activation (opening/closing) of the isolation and
dump valves is continuous during antilock operation.
The valves cycle rapidly in response to speed sensor inputs and control module signal commands. Cycle
times are measured in milliseconds.
As the demand for antilock mode brake operation
is decreased, the module deactivates the hydraulic
valve components to restore normal brake operation.

ANTILOCK
SERVICE
DIAGNOSIS
GENERAL INFORMATION An antilock system malfunction will be indicated
by illumination of the amber antilock warning lamp.
The red brake warning lamp may also illuminate.
If a problem occurs, system diagnosis should begin
with a fluid level check followed by a visual exami­
nation of the system electrical and hydraulic connec­

tions.
If obvious defects (low fluid, leaks, loose connections, etc.) are not evident, road test the vehi­

cle.
A road test should help determine if a malfunc­
tion is actually related to an antilock component.
During the road test, note if other conditions are
evident such as a low pedal, pull, grab, or similar condition. Remember that brake malfunctions such as low fluid, system leaks, parking brakes partially
applied, will also affect the antilock system. The idea
is to determine if a malfunction is actually related to
an anti-lock component.
If a road test does reveal a problem, repeat the
road test with the owner driving. Make sure the owner is not riding the brake pedal, or has forgotten
to release the parking brakes. Either situation will
generate a fault and cause the antilock light to illu­
minate.

SYSTEM FAULT
CODES
The antilock control module generates flash codes
to help identify the cause of an antilock system fault. Two different control modules are used with the
1992/1993 RWAL system. A type I module is used in
some early production models. All remaining produc­
tion models are equipped with a type II module. The type I and II modules are identified by the way
fault codes 9 and 11 are processed. If the vehicle has a type I module, codes 9 and 11 are not erased when
the ignition switch is turned to Off position. If the vehicle has a type II module, codes 9 and 11 are
erased when the switch is turned to Off.
FAULT CODES WITH TYPE I CONTROL
MODULE
The microprocessor in the electronic control module
has a memory and a self test feature. The self test
feature is activated whenever the ignition switch is
turned to Accessory or Run position. If a system fault is detected, the control module il­
luminates the antilock light and stores the fault code
in memory. Fault codes are retained in memory even after turning the ignition switch to Off position.
FAULT CODES WITH TYPE II CONTROL
MODULE The microprocessor in the electronic control module
has a memory and a self test feature. The self test
feature is activated whenever the ignition switch is
turned to Accessory or Run position.
If a system fault is detected, the control module
will illuminate the antilock indicator lamp and store
fault codes 1 through 8, 10 and 12 through 15 in the
microprocessor memory. When one of these fault
codes is generated, the control module will retain the code after the ignition switch is turned to the Off po­
sition.
When fault code 9 is generated, the code only re­
mains in microprocessor memory while the ignition switch is in Run position. Turning the ignition
switch to Off position erases fault code 9. However, if
the problem still exists when the switch is turned
back to Run position, code 9 will reappear in memory after 20 seconds and the antilock light will illumi­
nate once again.
When fault code 11 is generated, the antilock light
will illuminate when vehicle speed exceeds approxi­ mately 60.35 km/h (37.5 mph). Code 11 only remains in memory while the ignition switch is in the Run
position and the fault is present.
When the cause of a fault code 11 is corrected, the
antilock light goes off. Code 11 is erased when the ig­
nition switch is turned to Off position. However, if
the problem cause still exists when the ignition switch is turned to Run position, code 11 will reap­
pear when vehicle speed exceeds approximately 60.35 km/h (37.5 mph).

FAULT
CODE
CAPACITY
The microprocessor memory will store and display
only one fault code at a time. The stored code can be
displayed by grounding the RWAL diagnostic connec­
tor.

FAULT
CODE
IDENTIFICATION
To determine what the fault code is, momentarily
ground the RWAL diagnostic connector and count
the number of times the amber antilock lamp flashes. Fault codes and typical malfunctions are out­lined in Figure 8. Note that when a fault code is gen­
erated, the red brake warning lamp will also
illuminate. The initial flash will be a long flash followed by a
number of short flashes. The long flash indicates the
beginning of the fault number sequence and the short flashes are a continuation of that sequence.

DIAGNOSIS

PRELIMINARY
CHECKS

ENGINE COOLING SYSTEM OVERHEATING Establish what driving conditions caused the com­
plaint. Abnormal loads on the cooling system such as
the following may be the cause:

1.
PROLONGED IDLE, VERY HIGH AMBI­
ENT TEMPERATURE, SLIGHT TAIL WIND AT
IDLE, SLOW TRAFFIC, TRAFFIC JAMS, HIGH SPEED OR STEEP GRADES.
Driving techniques that avoid overheating are:
• Idle with A/C off when temperature gauge is at
end of normal range. * Increasing engine speed for more air flow is recom­
mended.

2.
TRAILER TOWING: Consult Trailer Towing section of owners manual.
Do not exceed limits.

3.
AIR CONDITIONING; ADD-ON OR AFTER
MARKET: A maximum cooling package should have been or­
dered with vehicle if add-on or after market A/C is
SYMPTOM AND ACTION

SYMPTOM
installed. If not, maximum cooling system compo­
nents should be installed for model involved per
manufacturer's specifications.

4.
RECENT SERVICE OR ACCIDENT RE­
PAIR:
Determine if any recent service has been performed
on vehicle that may effect cooling system. This may

be:

• Engine adjustments (incorrect timing)
• Slipping engine accessory drive belt(s) • Brakes (possibly dragging)
• Changed parts. Incorrect water pump or pump ro­
tating in wrong direction due to belt not correctly
routed
• Reconditioned radiator or cooling system refilling (possibly under filled or air trapped in system).
If investigation reveals none of the above as a
cause for an engine overheating complaint, refer to
the following Symptom and Action chart:
PRELIMINARY FIRST) ACTION
Blinking Engine Temperature
Warning Light or High Gauge indication - Without Coolant Loss
Normal during temporary operation
with
heavy load, towing
a
trailer,
high
outdoor temperatures, and/or on
a
steep
Loss
grade.

Coolant Loss
Hot Vehicle (Not Engine) Heat Damage,
Hot Carpet, Seat,
Hot
Catalytic
Converter,
Smoke, Burnt Odor
Hot Engine Crackling Noise Hot Smell
Severe Local Hot Spots
Coolant Color
Coolant Reserve Bottle Level Changes
Coolant Not Returning To Radiator
Improper refilling procedures
can
result
in
trapped air
in
the
system.
Subsequent
operation
of the
pressure cap and coolant reserve system
will
deaereate
the

cooling
system.
A low
coolant
level
will
then result
in the
Coolant Reserve
Tank. Add coolant.
If
condition persists,
refer
to
System
Diagnosis.

Check
heat shielding, exhaust
system,
engine emission controls, ignition
timing, engine misfiring.

A
moderate amount
of
sound from heating
metal
can
be
expected
with
any

vehicle. However,
a
crackling sound from
trie
thermostat
housing,
a hot
smell and/or severe local
hot
spots on
an
engine can indicate blocked coolant

passages,
bad castina, core sand deposits and subsequent blockage,
cracked cylinder block
or
head,
or
blown cylinder head gasket. Usually
accompanied
with
coolant
loss.

Coolant
color is
not
necessarily
an
indication
of
adequate
temperature
or

corrosion
protection.
Level changes
are to be
expected as coolant volume fluctuates
with
engine
temperature.
If the
level
in the
bottle
is
between
the
Maximum and Minimum
marks
at
normal engine operating temperature,
the
level
should
return
to

within
that
range
after
operation
at
elevated temperatures.

Coolant
will
not
return
to the
radiator
if the
radiator cap vent valve does
not

function,
if
an
air
leak destroys vacuum,
or if the
overflow
passage
is
blocked
or
restricted. Inspect
all
portions
of the
overflow
passage,
pressure

cap,
filler
neck nipple, hose, and
passages
within
the
bottle
for
vacuum leak
only. Coolant
return
failure
will
be
evident
by a low
level
in the
radiator.
Reserve
bottle
level
should increase during heat-up.

J9207-31