Brake servo DODGE RAM 1500 1998 2.G User Guide

INSTALLATION
INSTALLATION - ALL EXCEPT HYDROBOOST
NOTE: If master cylinder is replaced bleed cylinder
before installation.
NOTE: Make sure the output rod of the brake
booster is in position and retained by a output rod
retaining ring, by looking into the boosters master
cylinder mounting hole. This position will enable
the output rod to enter inside of the master cylinder
plunger sleeve during installation. Proper position
is obtained when the output rod is centered perpen-
dicular to the master cylinder mounting hole (Fig.
49).
NOTE: Prior to installing the master cylinder assem-
bly check that there is a vacuum seal present at the
shoulder of the master cylinder flange and it's neck.
A square seal must be present to ensure vacuum
integrity with the booster.
(1) Gently install the master cylinder on the
booster mounting studs.
NOTE: Take precautions to locate the master cylin-
der plunger over the booster output rod, before
installing the master cylinder. If correctly fitted the
master cylinder should slide easily onto the booster
output rod before the mounting studs are engaged
in the flange holes of the master cylinder.(2) Install new mounting nuts and tighten to 25
N´m (221 in. lbs.)
(3) Install the brake lines and tighten to 19 N´m
(170 in. lbs.)
(4) Reconnect the electrical connector for the low
fluid level switch.
(5) Fill and bleed the base brake system. (Refer to
5 - BRAKES - STANDARD PROCEDURE).
INSTALLATION - HYDROBOOST
NOTE: If master cylinder is replaced bleed cylinder
before installation.
(1) Install the master cylinder on the booster
mounting studs (Fig. 48).
(2) Install new mounting nuts and tighten to 25
N´m (221 in. lbs.)
(3) Install the brake lines and tighten to 19 N´m
(170 in. lbs.)
(4) Reconnect the elctrical connector for the low
fluid level switch.
(5) Fill and bleed the base brake system. (Refer to
5 - BRAKES - STANDARD PROCEDURE).
Fig. 48 HYDROBOOST MASTER CYLINDER
1 - HYDROBOOST UNIT
2 - MASTER CYLINDER RESERVOIR
3 - MASTER CYLINDER
4 - MOUNTING NUTS
Fig. 49 OUTPUT ROD ORIENTATION
1 - MASTER CYLINDER RESERVOIR
2 - CHECK VALVE
3 - VACUUM BOOST UNIT
4 - BOOSTER MOUNTING STUDS
5 - INPUT ROD
6 - OUTPUT ROD
7 - MASTER CYLINDER MOUNTING STUDS
8 - MASTER CYLINDER PLUNGER SLEEVE
9- MASTER CYLINDER
10 - ELECTRICAL CONNECTOR
DRBRAKES - BASE 5 - 27
MASTER CYLINDER (Continued)

HYDRAULIC BOOSTER DIAGNOSIS CHART
CONDITION POSSIBLE CAUSES CORRECTION
Slow Brake Pedal Return 1. Excessive seal friction in booster. 1. Replace booster.
2. Faulty spool valve action. 2. Replace booster.
3. Restriction in booster return hose. 3. Replace hose.
4. Damaged input rod. 4. Replace booster.
Excessive Brake Pedal
Effort.1. Internal or external seal leakage. 1. Replace booster.
2. Faulty steering pump. 2. Replace pump.
Brakes Self Apply 1. Dump valve faulty. 1. Replace booster.
2. Contamination in hydraulic
system.2. Flush hydraulic system and replace
booster.
3. Restriction in booster return hose. 3. Replace hose.
Booster Chatter, Pedal
Vibration1. Slipping pump belt. 1. Replace power steering belt.
2. Low pump fluid level. 2. Fill pump and check for leaks.
Grabbing Brakes 1. Low pump flow. 1. Test and repair/replace pump.
2. Faulty spool valve action. 2. Replace booster.
STANDARD PROCEDURE - BLEEDING
The hydraulic booster is generally self-bleeding,
this procedure will normally bleed the air from the
booster. Normal driving and operation of the unit will
remove any remaining trapped air.
(1) Fill power steering pump reservoir.
(2) Disconnect fuel shutdown relay and crank the
engine for several seconds, Refer to Fuel System for
relay location and WARNING.
(3) Check fluid level and add if necessary.
(4) Connect fuel shutdown relay and start the
engine.
(5) Turn the steering wheel slowly from lock to
lock twice.
(6) Stop the engine and discharge the accumulator
by depressing the brake pedal 5 times.
(7) Start the engine and turn the steering wheel
slowly from lock to lock twice.
(8) Turn off the engine and check fluid level and
add if necessary.
NOTE: If fluid foaming occurs, wait for foam to dis-
sipate and repeat steps 7 and 8.
REMOVAL
NOTE: If the booster is being replaced because the
power steering fluid is contaminated, flush the
power steering system before replacing the booster.
(1) With engine off depress the brake pedal 5
times to discharge the accumulator.
(2) Remove brake lines from master cylinder.
(3) Remove mounting nuts from the master cylin-
der.
(4) Remove the bracket from the hydraulic booster
lines and master cylinder mounting studs.
(5) Remove the master cylinder.
(6) Remove the return hose and the two pressure
lines from the hydraulic booster (Fig. 55).
(7) Remove the booster push rod clip, washer and
rod remove from the brake pedal.
(8) Remove the mounting nuts from the hydraulic
booster and remove the booster.
DRBRAKES - BASE 5 - 31
HYDRO-BOOST BRAKE BOOSTER (Continued)

Engine Control Module (ECM) over the PCI data bus
to illuminate the check gauges indicator for a coolant
temperature high condition.
²Fasten Seat Belt Warning- The instrument
cluster chime tone generator will generate repetitive
chimes at a slow rate each time the ignition switch is
turned to the On or Start positions to announce that
the hard wired inputs from the seat belt switch and
the ignition switch indicate that the driver side front
seat belt is not fastened. The chimes will continue to
sound for a duration of about six seconds, until the
driver side front seat belt is fastened, or until the
ignition switch is turned to the Off position, which-
ever occurs first.
²Head/Park Lamps-On Warning- The instru-
ment cluster chime tone generator will generate
repetitive chimes at a slow rate to announce that the
hard wired inputs from the driver door ajar switch,
the ignition switch, and the exterior lighting circuitry
of the headlamp switch indicate that the exterior
lamps are turned On with the driver door opened
and the ignition switch in the Off position. The
chimes will continue to sound until the exterior
lamps are turned Off, the driver door is closed, or the
ignition switch is turned to the On position, or the
battery protection time-out expires, whichever occurs
first.
²Key-In-Ignition Warning- The instrument
cluster chime tone generator will generate repetitive
chimes at a slow rate to announce that the hard
wired inputs from the driver door ajar switch, the
ignition switch, and the key-in ignition circuitry of
the ignition switch indicate that the key is in the
ignition lock cylinder with the driver door opened
and the ignition switch in the Off position. The
chimes will continue to sound until the key is
removed from the ignition lock cylinder, the driver
door is closed, or the ignition switch is turned to the
On position, whichever occurs first.
²Low Fuel Warning- The instrument cluster
chime tone generator will generate one chime tone
when the low fuel indicator is illuminated by the
instrument cluster. The instrument cluster uses a
percent tank full message input received from the
PCM over the PCI data bus indicating that there is
less than about one-eighth tank of fuel remaining to
illuminate the low fuel indicator. This chime feature
will only occur once in an ignition cycle.
²Low Oil Pressure Warning (Diesel Engine
Only)- The instrument cluster chime tone generator
will generate repetitive chimes at a fast rate when
the check gauges indicator is illuminated for a low oil
pressure condition. The instrument cluster uses
engine speed and oil pressure message inputs
received from the diesel Engine Control Module
(ECM) over the PCI data bus indicating that theengine is running and that the oil pressure is low to
illuminate the check gauges indicator. The chimes
will continue to sound for five seconds, until the
engine oil pressure message indicates that the oil
pressure is not low, or until the engine speed mes-
sage indicates that the engine is not running, which-
ever occurs first. This chime tone will only occur once
in an ignition cycle.
²Low Wash Warning- The instrument cluster
chime tone generator will generate one chime tone
when the low washer fluid indicator is illuminated by
the instrument cluster. The instrument cluster uses a
message input received from the Front Control Mod-
ule (FCM) over the PCI data bus indicating that
washer fluid level is low within the washer reservoir.
This chime feature will only occur once in an ignition
cycle.
²Overspeed Warning- The instrument cluster
chime tone generator will generate one chime tone to
announce that a vehicle speed message input
received from the PCM over the PCI data bus indi-
cates that the vehicle speed is above a pre-programed
limit.
²Park Brake Reminder- The instrument clus-
ter chime tone generator will generate ten repetitive
chimes at a slow rate to announce that the hard
wired input from the park brake switch and a vehicle
speed message input received from the PCM over the
PCI data bus indicates that the park brake is applied
and the vehicle is moving. This chime feature will
repeat each time the input conditions are met.
²Sentry Key Immobilizer System ªCustomer
Learnº Mode Announcement- This chime feature
is only active on vehicles equipped with the optional
Sentry Key Immobilizer System (SKIS) and sold in
markets where the optional ªCustomer Learnº pro-
gramming feature is available. The instrument clus-
ter chime tone generator will generate one chime to
announce that a status message input received from
the Sentry Key Immobilizer Module (SKIM) over the
PCI data bus indicates that the SKIS is in the ªCus-
tomer Learnº mode, which is used for programming
additional sentry key transponders.
²Transmission Temperature High Warning
(Automatic Transmission only)- The instrument
cluster chime tone generator will generate repetitive
chimes at a slow rate when the transmission temper-
ature indicator is illuminated for a high or critical
transmission fluid temperature condition. The instru-
ment cluster uses transmission temperature message
inputs received from the Transmission Control Mod-
ule (TCM) over the PCI data bus to illuminate the
indicator for a transmission temperature high condi-
tion.
²Turn Signal On Warning- The instrument
cluster chime tone generator will generate repetitive
8B - 2 CHIME/BUZZERDR
CHIME WARNING SYSTEM (Continued)

(2) Disconnect and isolate the remote battery neg-
ative cable terminal.
(3) Remove the battery from the vehicle. Refer to
the procedure in this group.
(4) One at a time, trace the battery cable retaining
pushpins, fasteners and routing clips until the cable
is free from the vehicle.
(5) Remove the battery cable from the engine com-
partment.
INSTALLATION
(1) Position the battery cable in the engine com-
partment.
(2) One at a time, install the battery cable retain-
ing pushpins, fasteners and routing clips until the
cable is installed exactly where it was in the vehicle.
Refer to Wiring for illustrations.
(3) Install the battery in the vehicle. Refer to the
procedure in this group.
(4) Connect the battery negative cable terminal.
BATTERY TRAY
DESCRIPTION
The molded plastic tray battery tray is located in
the left front corner of the engine compartment. On
this model, the battery tray also provides an anchor
point for the anti-lock brake controller, cruise control
servo (if equipped) and the integrated power module
(Fig. 15). The battery hold down hardware is con-
tained within the battery tray. A hole in the bottom
of the battery tray is fitted with a battery tempera-
ture sensor. Refer to Charging System for more infor-
mation on the battery temperature sensor.
OPERATION
The battery tray and the battery hold down hard-
ware combine to secure and stabilize the battery in
the engine compartment, which prevents battery
movement during even the most extreme vehicle
operation. Unrestrained battery movement during
vehicle operation could result in damage to the vehi-
cle, the battery, or both.
REMOVAL
LEFT SIDE
(1) Remove the battery from the battery tray
(Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BAT-
TERY - REMOVAL).
(2) Remove the integrated power module (Refer to
8 - ELECTRICAL/POWER DISTRIBUTION/INTEL-
LIGENT POWER MODULE - REMOVAL).
(3) Disconnect the wire harness retainers from the
battery tray assembly.
(4) Remove the anti-lock brake controller (if
equipped) retaining bolts and support the brake con-
troller with mechanics wire. It is not necessary to
completely remove the anti-lock brake control unit.
(5) Remove the left front wheelhouse splash shiel-
d(Refer to 23 - BODY/EXTERIOR/LF WHEEL-
HOUSE SPLASH SHIELD - REMOVAL).
(6) Mark the location of the cruise servo (if
equipped) and remove the retaining screws. Position
the servo out of the way.
(7) Remove the battery temperature sensor from
the battery tray (Refer to 8 - ELECTRICAL/CHARG-
ING/BATTERY TEMPERATURE SENSOR -
REMOVAL).
(8) Disconnect the purge solenoid from its mount-
ing bracket.
(9) Disconnect the left front fender ground wire.
(10) Remove the remaining battery tray retaining
bolts (Fig. 16).
(11) Remove the battery tray from the vehicle.
RIGHT SIDE
(1) Remove the battery from the battery tray
(Refer to 8 - ELECTRICAL/BATTERY SYSTEM/BAT-
TERY - REMOVAL).
Fig. 15 DR Battery Tray
1 - BATTERY TRAY ASSEMBLY
2 - BATTERY TEMPERATURE SENSOR
3 - ANTI-LOCK BRAKE CONTROLLER MOUNTING LOCATION
4 - INTEGRATED POWER MODULE MOUNTING SANCTION
DRBATTERY SYSTEM 8F - 17
BATTERY CABLES (Continued)

(2) Remove the right front wheelhouse splash
shield.
(3) Disconnect the right front fender ground wire.
(4) Remove fasteners from grid heater relay
bracket.
(5) Remove air box.
(6) Remove the remaining battery tray retaining
bolts (Fig. 17).
(7) Remove the battery tray from the vehicle.
INSTALLATION
LEFT SIDE
(1) Position the battery tray assembly and install
the retaining bolts.
(2) Connect the left front fender ground wire.
(3) Install the purge solenoid on its mounting
bracket.
(4) Install the battery temperature sensor in the
battery tray (Refer to 8 - ELECTRICAL/CHARGING/
BATTERY TEMPERATURE SENSOR - INSTALLA-
TION).
(5) Install the cruise servo (if equipped) and
retaining screws.
(6) Install the left front wheelhouse splash shield
(Refer to 23 - BODY/EXTERIOR/LF WHEELHOUSE
SPLASH SHIELD - INSTALLATION).
(7) Install the anti-lock brake controller (if
equipped).
(8) Connect the wire harness retainers on the bat-
tery tray assembly.
(9) Install the integrated power module (Refer to 8
- ELECTRICAL/POWER DISTRIBUTION/INTELLI-
GENT POWER MODULE - INSTALLATION).
(10) Install the battery (Refer to 8 - ELECTRI-
CAL/BATTERY SYSTEM/BATTERY - INSTALLA-
TION).
RIGHT SIDE
(1) Position the battery tray assembly and install
the retaining bolts.
(2) Connect the right front fender ground wire.
(3) Install the air box.
(4) Install the grid heater relay bracket.
(5) Install the right front wheelhouse splash
shield.
(6) Install the battery (Refer to 8 - ELECTRICAL/
BATTERY SYSTEM/BATTERY - INSTALLATION).
Fig. 16 Lower Battery Tray Retaining Bolts
1 - BATTERY TRAY ASSEMBLY
2 - BATTERY TRAY RETAINING BOLTS
3 - CRUISE CONTROL SERVO
Fig. 17 RIGHT SIDE BATTERY TRAY
8F - 18 BATTERY SYSTEMDR
BATTERY TRAY (Continued)

BRAKE/PARK BRAKE
INDICATOR
DESCRIPTION
A brake indicator is standard equipment on all
instrument clusters (Fig. 10). The brake indicator is
located near the lower edge of the instrument cluster,
between the tachometer and the speedometer. The
brake indicator consists of stencil-like cutouts of the
word ªBRAKEº and the International Control and
Display Symbol icon for ªBrake Failureº in the
opaque layer of the instrument cluster overlay. The
dark outer layer of the overlay prevents the indicator
from being clearly visible when it is not illuminated.
A red Light Emitting Diode (LED) behind the cutout
in the opaque layer of the overlay causes the
ªBRAKEº text and the icon to appear in red through
the translucent outer layer of the overlay when the
indicator is illuminated from behind by the LED,
which is soldered onto the instrument cluster elec-
tronic circuit board. The brake indicator is serviced
as a unit with the instrument cluster.
OPERATION
The brake indicator gives an indication to the vehi-
cle operator when the parking brake is applied, when
there are certain brake hydraulic system malfunc-
tions as indicated by a low brake hydraulic fluid level
condition, or when the brake fluid level switch is dis-
connected. The brake indicator can also give an indi-
cation when certain faults are detected in the
Antilock Brake System (ABS). This indicator is con-
trolled by a transistor on the instrument cluster cir-
cuit board based upon cluster programming,
electronic messages received by the cluster from the
Controller Antilock Brake (CAB) over the Program-
mable Communications Interface (PCI) data bus, and
a hard wired input from the park brake switch. The
brake indicator Light Emitting Diode (LED) is com-
pletely controlled by the instrument cluster logic cir-
cuit, and that logic will only allow this indicator to
operate when the instrument cluster receives a bat-
tery current input on the fused ignition switch out-
put (run-start) circuit. Therefore, the LED will
always be off when the ignition switch is in any posi-
tion except On or Start. The LED only illuminates
when it is provided a path to ground by the instru-
ment cluster transistor. The instrument cluster will
turn on the brake indicator for the following reasons:²Bulb Test- Each time the ignition switch is
turned to the On position the brake indicator is illu-
minated by the instrument cluster for about two sec-
onds as a bulb test.
²Brake Lamp-On Message- Each time the
cluster receives a lamp-on message from the CAB,
the brake indicator will be illuminated. The CAB can
also send brake lamp-on messages as feedback dur-
ing ABS diagnostic procedures. The indicator
remains illuminated until the cluster receives a
lamp-off message from the CAB, or until the ignition
switch is turned to the Off position, whichever occurs
first.
²Park Brake Switch Input- Each time the
cluster detects ground on the park brake switch
sense circuit (park brake switch closed = park brake
applied or not fully released) while the ignition
switch is in the On position, the brake indicator
flashes on and off. The indicator continues to flash
until the park brake switch sense input to the cluster
is an open circuit (park brake switch open = park
brake fully released), or until the ignition switch is
turned to the Off position, whichever occurs first.
²Actuator Test- Each time the instrument clus-
ter is put through the actuator test, the brake indi-
cator will be turned on, then off again during the
bulb check portion of the test to confirm the function-
ality of the LED and the cluster control circuitry.
The park brake switch on the park brake pedal
mechanism provides a hard wired ground input to
the instrument cluster circuitry through the park
brake switch sense circuit whenever the park brake
is applied or not fully released. The CAB continually
monitors the ABS system circuits and sensors,
including the brake fluid level switch on the brake
master cylinder reservoir, to decide whether the sys-
tem is in good operating condition. The CAB then
sends the proper lamp-on or lamp-off messages to the
instrument cluster. If the CAB sends a lamp-on mes-
sage after the bulb test, it indicates that the CAB
has detected a brake hydraulic system malfunction
and/or that the ABS system has become inoperative.
The CAB will store a Diagnostic Trouble Code (DTC)
for any malfunction it detects.
For further diagnosis of the brake indicator or the
instrument cluster circuitry that controls the LED,
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). The park brake
switch input to the instrument cluster can be diag-
nosed using conventional diagnostic tools and meth-
ods. For proper diagnosis of the brake fluid level
switch, the ABS, the CAB, the PCI data bus, or the
electronic message inputs to the instrument cluster
that control the brake indicator, a DRBIIItscan tool
is required. Refer to the appropriate diagnostic infor-
mation.
Fig. 10 Brake Indicator
DRINSTRUMENT CLUSTER 8J - 19

BRAKE LAMP
REMOVAL
REMOVAL - WITH CARGO BOX
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the tail lamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/TAIL
LAMP UNIT - REMOVAL).
(3) Remove the lamp back plate from the tail lamp
unit.
(4) Release the brake lamp bulb locking tabs and
remove the bulb from the back plate.
REMOVAL - WITHOUT CARGO BOX
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the four screws that secure the tail
lamp lens to the tail lamp housing (Fig. 3).
(3) Separate the tail lamp lens from the tail lamp
housing.
(4) Push the brake lamp bulb inward and rotate it
counter-clockwise.
(5) Remove the brake lamp bulb from the brake
lamp socket.
INSTALLATION
INSTALLATION - WITH CARGO BOX
(1) Install the brake lamp bulb into the lamp back
plate.
(2) Install the lamp back plate onto the tail lamp
unit.
(3) Install the tail lamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/TAIL
LAMP UNIT - INSTALLATION).
(4) Reconnect the negative battery cable.
INSTALLATION - WITHOUT CARGO BOX
(1) Install the brake lamp bulb into the brake
lamp socket by pushing inward and rotating it clock-
wise.
NOTE: Install the tail lamp lens with the clear por-
tion (back-up lens) at the top of the housing. Make
sure that the gasket is correctly in place and not
twisted or torn.
(2) Position the tail lamp lens and gasket onto the
tail lamp unit.
NOTE: Do not overtighten the tail lamp lens screws
or damage to the tail lamp lens may result.
(3) Install the four screws that secure the tail
lamp lens to the tail lamp unit. Tighten the screws
securely.
(4) Reconnect the negative battery cable.
BRAKE LAMP SWITCH
DESCRIPTION
The plunger type brake lamp switch is mounted on
a bracket attached to the base of the steering col-
umn, under the instrument panel.
CAUTION: The switch can only be adjusted during
initial installation. If the switch is not adjusted prop-
erly a new switch must be installed.
OPERATION
The brake lamp switch is hard wired to the Center
High Mount Stop Lamp (CHMSL) and also moni-
tored by the Instrument Cluster for use by the brake
lamp, speed control brake sensor circuits and elec-
tronic brake distribution (EBD). The brake lamp cir-
cuit is open until the plunger is depressed. The speed
control and brake sensor circuits are closed until the
plunger is depressed. When the brake lamp switch
transitions, the CHMSL transitions and instrument
cluster transmits a brake applied/released message
on the bus. The Integrated Power Module (IPM) will
then transition the brake lamps.
When the brake light switch is activated, the Pow-
ertrain Control Module (PCM) receives an input indi-
cating that the brakes are being applied. After
receiving this input, the PCM maintains idle speed to
a scheduled rpm through control of the Idle Air Con-
trol (IAC) motor. The brake switch input is also used
to disable vent and vacuum solenoid output signals
to the speed control servo.
Fig. 3 Tail Lamp Lens
DRLAMPS/LIGHTING - EXTERIOR 8L - 9

Vehicles equipped with the speed control option use
a dual function brake lamp switch. The PCM moni-
tors the state of the dual function brake lamp switch.
The brake switch is equipped with three sets of
contacts, one normally open and the other two nor-
mally closed (brakes disengaged). The PCM sends a
12 volt signal to one of the normally closed contacts
in the brake switch, which is returned to the PCM as
a brake switch state signal. With the contacts closed,
the 12 volt signal is pulled to ground causing the sig-
nal to go low. The low voltage signal, monitored by
the PCM, indicates that the brakes are not applied.
When the brakes are applied, the contacts open,
causing the PCM's output brake signal to go high,
disengaging the speed control, cutting off PCM power
to the speed control solenoids.
The second set of normally closed contacts supplies
12 volts from the PCM any time speed control is
turned on. Through the brake switch, voltage is
routed to the speed control servo solenoids. The
speed control solenoids (vacuum, vent and dump) are
provided this voltage any time the speed control is
ON and the brakes are disengaged.
When the driver applies the brakes, the contacts
open and voltage is interrupted to the solenoids. The
normally open contacts are fed battery voltage. When
the brakes are applied, battery voltage is supplied to
the brake lamps.
The brake lamp switch can only be adjusted once.
That is at the initial installation of the switch. If the
switch is not adjusted properly or has been removed,
a new switch must be installed and adjusted.
DIAGNOSIS AND TESTING - BRAKE LAMP
SWITCH
The brake lamp switch can be tested with an ohm-
meter. The ohmmeter is used to check continuity
between the pin terminals (Fig. 4).
SWITCH CIRCUIT IDENTIFICATION
²Terminals 1 and 2: brake lamp circuit
²Terminals 3 and 4: RWAL/ABS module and Pow-
ertrain Control Module (PCM) circuit
²Terminals 5 and 6: speed control circuit
SWITCH CONTINUITY TEST
NOTE: Disconnect switch harness before testing
switch continuity.
With switch plunger extended, attach test leads to
pins 1 and 2. Replace switch if meter indicates no
continuity.
With switch plunger retracted, attach test leads to
pins 3 and 4. Replace switch if meter indicates no
continuity.With switch plunger retracted, attach test leads to
pins 5 and 6. Replace switch if meter indicates no
continuity.
REMOVAL
(1) Disconnect the switch harness (Fig. 5).
(2) Press and hold the brake pedal in applied posi-
tion.
(3) Rotate the switch counterclockwise about 30É to
align the switch lock tab with the notch in bracket.
(4) Pull the switch rearward out of the mounting
bracket and release the brake pedal.
Fig. 4 Brake Lamp Switch Terminal Identification
1 - TERMINAL PINS
2 - PLUNGER TEST POSITIONS
Fig. 5 Brake Lamp Switch & Bracket
1 - RELEASE LEVER
2 - BRACKET
3 - BRAKE PEDAL SUPPORT
4 - BRAKE LAMP SWITCH
8L - 10 LAMPS/LIGHTING - EXTERIORDR
BRAKE LAMP SWITCH (Continued)

5.9L Diesel With Manual Trans.
The speed control system is fully electronically con-
trolled by the Engine Control Module (ECM).A
cable and a vacuum controlled servo are not
used if the vehicle is equipped with a manual
transmission and a diesel engine. This is a ser-
vo-less system.The controls consist of two steering
wheel mounted switches. The switches are labeled:
ON/OFF, RES/ACCEL, SET, COAST, and CANCEL.
The system is designed to operate at speeds above
30 mph (50 km/h).
WARNING: THE USE OF SPEED CONTROL IS NOT
RECOMMENDED WHEN DRIVING CONDITIONS DO
NOT PERMIT MAINTAINING A CONSTANT SPEED,
SUCH AS IN HEAVY TRAFFIC OR ON ROADS THAT
ARE WINDING, ICY, SNOW COVERED, OR SLIP-
PERY.
OPERATION
When speed control is selected by depressing the
ON switch, the PCM (the ECM with a diesel engine)
allows a set speed to be stored in its RAM for speed
control. To store a set speed, depress the SET switch
while the vehicle is moving at a speed between 35
and 85 mph. In order for the speed control to engage,
the brakes cannot be applied, nor can the gear selec-
tor be indicating the transmission is in Park or Neu-
tral.
The speed control can be disengaged manually by:
²Stepping on the brake pedal
²Depressing the OFF switch
²Depressing the CANCEL switch.
²Depressing the clutch pedal (if equipped).
NOTE: Depressing the OFF switch or turning off the
ignition switch will erase the set speed stored in
the PCM (the ECM with a diesel engine).
For added safety, the speed control system is pro-
grammed to disengage for any of the following condi-
tions:
²An indication of Park or Neutral
²A rapid increase rpm (indicates that the clutch
has been disengaged)
²Excessive engine rpm (indicates that the trans-
mission may be in a low gear)
²The speed signal increases at a rate of 10 mph
per second (indicates that the coefficient of friction
between the road surface and tires is extremely low)
²The speed signal decreases at a rate of 10 mph
per second (indicates that the vehicle may have
decelerated at an extremely high rate)Once the speed control has been disengaged,
depressing the RES/ACCEL switch (when speed is
greater than 30 mph) restores the vehicle to the tar-
get speed that was stored in the PCM (the ECM with
a diesel engine).
While the speed control is engaged, the driver can
increase the vehicle speed by depressing the RES/AC-
CEL switch. The new target speed is stored in the
PCM (the ECM with a diesel engine) when the RES/
ACCEL is released. The PCM (the ECM with a diesel
engine) also has a9tap-up9feature in which vehicle
speed increases at a rate of approximately 2 mph for
each momentary switch activation of the RES/AC-
CEL switch.
A ªtap downº feature is used to decelerate without
disengaging the speed control system. To decelerate
from an existing recorded target speed, momentarily
depress the COAST switch. For each switch activa-
tion, speed will be lowered approximately 1 mph.DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - VACUUM SUPPLY
TEST
3.7L / 4.7L Gas Powered Engines
3.7L/4.7L gas powered engines: actual engine vac-
uum, a vacuum reservoir, a one-way check valve and
vacuum lines are used to supply vacuum to the speed
control servo.
(1) Disconnect vacuum hose at speed control servo
and install a vacuum gauge into the disconnected
hose.
(2) Start engine and observe gauge at idle. Vac-
uum gauge should read at least ten inches of mer-
cury.
(3) If vacuum is less than ten inches of mercury,
determine source of leak. Check vacuum line to
engine for leaks. Also check actual engine intake
manifold vacuum. If manifold vacuum does not meet
this requirement, check for poor engine performance
and repair as necessary.
(4) If vacuum line to engine is not leaking, check
for leak at vacuum reservoir. To locate and gain
access to reservoir, refer to Vacuum Reservoir Remov-
al/Installation in this group. Disconnect vacuum line
at reservoir and connect a hand-operated vacuum
pump to reservoir fitting. Apply vacuum. Reservoir
vacuum should not bleed off. If vacuum is being lost,
replace reservoir.
8P - 2 SPEED CONTROLDR
SPEED CONTROL (Continued)

(5) Verify operation of one-way check valve and
check it for leaks.
(a) Locate one-way check valve. The valve is
located in vacuum line between vacuum reservoir
and engine vacuum source. Disconnect vacuum
hoses (lines) at each end of valve.
(b) Connect a hand-operated vacuum pump to
reservoir end of check valve. Apply vacuum. Vac-
uum should not bleed off. If vacuum is being lost,
replace one-way check valve.
(c) Connect a hand-operated vacuum pump to
vacuum source end of check valve. Apply vacuum.
Vacuum should flow through valve. If vacuum is
not flowing, replace one-way check valve. Seal the
fitting at opposite end of valve with a finger and
apply vacuum. If vacuum will not hold, diaphragm
within check valve has ruptured. Replace valve.
5.7 Gas
Vacuum is not used for any part of the speed con-
trol system if equipped with a 5.7L V-8 engine.
5.9L Diesel Engine With Manual Trans.
Vacuum is not used for any part of the speed con-
trol system if equipped with a diesel engine and a
manual transmission.
5.9L Diesel Engines With Automatic Trans.
If equipped with a diesel powered engine and an
automatic transmission, an electric vacuum pump
and vacuum lines are used to supply vacuum to the
speed control servo. A vacuum reservoir is not used.
DIAGNOSIS AND TESTING - ROAD TEST
Perform a vehicle road test to verify reports of
speed control system malfunction. The road test
should include attention to the speedometer. Speed-ometer operation should be smooth and without flut-
ter at all speeds.
Flutter in the speedometer indicates a problem
which might cause surging in the speed control sys-
tem. The cause of any speedometer problems should
be corrected before proceeding. Refer to Instrument
Cluster for speedometer diagnosis.
If a road test verifies a system problem and the
speedometer operates properly, check for:
²A Diagnostic Trouble Code (DTC). If a DTC
exists, conduct tests per the Powertrain Diagnostic
Procedures service manual.
²A misadjusted brake (stop) lamp switch. This
could also cause an intermittent problem.
²Loose, damaged or corroded electrical connec-
tions at the servo (if used). Corrosion should be
removed from electrical terminals and a light coating
of Mopar MultiPurpose Grease, or equivalent,
applied.
²Leaking vacuum reservoir (if used).
²Loose or leaking vacuum hoses or connections (if
used).
²Defective one-way vacuum check valve (if used).
²Secure attachment of both ends of the speed con-
trol servo cable (if used).
²Smooth operation of throttle linkage (if used)
and throttle body air valve.
²Failed speed control servo (if used). Do the servo
vacuum test.
CAUTION: When test probing for voltage or conti-
nuity at electrical connectors, care must be taken
not to damage connector, terminals or seals. If
these components are damaged, intermittent or
complete system failure may occur.
SPECIFICATIONS
TORQUE - SPEED CONTROL
DESCRIPTION N-m Ft. Lbs. In. Lbs.
Servo Mounting Bracket-
to-Servo Nuts7-60
Servo Mounting Bracket-
to-Battery Tray Screws4-30
Speed Control Switch
Mounting Screws1.7 - 15
Vacuum Reservoir
Mounting Nuts3-20
DRSPEED CONTROL 8P - 3
SPEED CONTROL (Continued)