1998 DODGE RAM 1500 transmission

into the passenger airbag door on the instrument
panel above the glove box (Fig. 2). Vehicles with the
airbag system can also be identified by the airbag
indicator, which will illuminate in the instrument
cluster for about six seconds as a bulb test each time
the ignition switch is turned to the On position. A
pyrotechnic-type seat belt tensioner is integral to the
front outboard seat belt retractors mounted on each
lower B-pillar of all models equipped with dual front
airbags.
²Side Curtain Airbags- Optional side curtain
airbags are available for this model when it is also
equipped with dual front airbags. This airbag systemis a passive, inflatable, Supplemental Restraint Sys-
tem (SRS) and vehicles with this equipment can be
readily identified by a molded identification trim but-
ton with the ªSRS - AIRBAGº logo located on the
headliner above each B-pillar (Fig. 2).
The supplemental restraint system includes the
following major components, which are described in
further detail elsewhere in this service information:
²Airbag Control Module- The Airbag Control
Module (ACM) is also sometimes referred to as the
Occupant Restraint Controller (ORC). The ACM is
located on a mount on the floor panel transmission
tunnel, below the center of the instrument panel.
Fig. 1 Supplemental Restraint System
1 - AIRBAG CONTROL MODULE
2 - PASSENGER AIRBAG
3 - PASSENGER AIRBAG ON/OFF SWITCH (STD CAB ONLY)
4 - DRIVER AIRBAG5 - SIDE CURTAIN AIRBAG (2)
6 - SIDE IMPACT SENSOR (2 - W/SIDE CURTAIN AIRBAGS
ONLY)
7 - SEAT BELT TENSIONER (2)
DRRESTRAINTS 8O - 3
RESTRAINTS (Continued)

If the stored DTC information is successfully erased,
go to Step 9.
(9) Turn the ignition switch to the Off position for
about fifteen seconds, and then back to the On posi-
tion. Observe the airbag indicator in the instrument
cluster. It should illuminate for six to eight seconds,
and then go out. This indicates that the supplemen-
tal restraint system is functioning normally and that
the repairs are complete. If the airbag indicator fails
to light, or lights and stays on, there is still an active
supplemental restraint system fault or malfunction.
Refer to the appropriate diagnostic information to
diagnose the problem.
ACM COVER
REMOVAL
The Airbag Control Module (ACM) cover is used
only on models with an automatic transmission. Mod-
els with a manual transmission require that the floor
console be removed to access the ACM for service.
(Refer to 23 - BODY/INTERIOR/FLOOR CONSOLE -
REMOVAL).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) Using a trim stick or another suitable wide
flat-bladed tool, gently pry each side of the ACM
cover away from the instrument panel at each side of
the center bracket on the floor panel transmission
tunnel far enough to disengage the two snap clip
retainers from the instrument panel receptacles (Fig.
6).
(3) Remove the ACM cover from the instrument
panel.
INSTALLATION
The Airbag Control Module (ACM) cover is used
only on models with an automatic transmission. Mod-
els with a manual transmission require that the floor
console be reinstalled following ACM service. (Refer
to 23 - BODY/INTERIOR/FLOOR CONSOLE -
INSTALLATION).
WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
(1) Position the ACM cover to the instrument
panel (Fig. 6).
(2) Align the snap clip retainer on each side of the
ACM cover with the instrument panel receptacle at
each side of the center bracket on the floor panel
transmission tunnel.
(3) Using hand pressure, press firmly and evenly
on the outside of the ACM cover over each snap clip
retainer location until each retainer is fully engaged
in its instrument panel receptacle.
(4) Reconnect the battery negative cable.
Fig. 6 ACM Cover Remove/Install
1 - INSTRUMENT PANEL RECEPTACLE (2)
2 - ACM COVER
8O - 10 RESTRAINTSDR
RESTRAINTS (Continued)

AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is also some-
times referred to as the Occupant Restraint Control-
ler (ORC) (Fig. 7). The ACM is concealed below the
instrument panel center stack in the passenger com-
partment of the vehicle, where it is secured by three
screws to a stamped steel mounting bracket welded
onto the top of the floor panel transmission tunnel
just forward of the instrument panel center support
bracket. Concealed within a hollow in the center of
the die cast aluminum ACM housing is the electronic
circuitry of the ACM which includes a microproces-
sor, an electronic impact sensor, an electronic safing
sensor, and an energy storage capacitor. A stamped
metal cover plate is secured to the bottom of the
ACM housing with four screws to enclose and protect
the internal electronic circuitry and components.
An arrow printed on the label on the top of the
ACM housing provides a visual verification of the
proper orientation of the unit, and should always be
pointed toward the front of the vehicle. The ACM
housing has integral mounting flanges on three cor-
ners. The mounting flange to the left of the connector
receptacle has an integral locating pin on its lower
surface. Both left side flanges have round mounting
holes, while the flange on the right side has a slotted
mounting hole. A molded plastic electrical connector
with two receptacles, one containing twenty-four ter-
minal pins and the other containing thirty-two termi-
nal pins, exits the rearward facing side of the ACM
housing. These terminal pins connect the ACM to the
vehicle electrical system through two dedicated takeouts and connectors of the instrument panel wire
harness.
The impact sensor and safing sensor internal to
the ACM are calibrated for the specific vehicle, and
are only serviced as a unit with the ACM. In addi-
tion, there are unique versions of the ACM for light
and heavy-duty models, and for vehicles with or
without the optional side curtain airbags. The ACM
cannot be repaired or adjusted and, if damaged or
faulty, it must be replaced.
OPERATION
The microprocessor in the Airbag Control Module
(ACM) contains the supplemental restraint system
logic circuits and controls all of the supplemental
restraint system components. The ACM uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Programma-
ble Communications Interface (PCI) data bus net-
work. This method of communication is used for
control of the airbag indicator in the ElectroMechani-
cal Instrument Cluster (EMIC) and for supplemental
restraint system diagnosis and testing through the
16-way data link connector located on the driver side
lower edge of the instrument panel. (Refer to 8 -
ELECTRICAL/INSTRUMENT CLUSTER/AIRBAG
INDICATOR - OPERATION).
The ACM microprocessor continuously monitors all
of the supplemental restraint system electrical cir-
cuits to determine the system readiness. If the ACM
detects a monitored system fault, it sets an active
and stored Diagnostic Trouble Code (DTC) and sends
electronic messages to the EMIC over the PCI data
bus to turn on the airbag indicator. An active fault
only remains for the duration of the fault, or in some
cases for the duration of the current ignition switch
cycle, while a stored fault causes a DTC to be stored
in memory by the ACM. For some DTCs, if a fault
does not recur for a number of ignition cycles, the
ACM will automatically erase the stored DTC. For
other internal faults, the stored DTC is latched for-
ever.
In standard cab models, the ACM also monitors a
resistor multiplexed input from the passenger airbag
on/off switch and provides a control output for the
Off indicator in the switch through a passenger air-
bag indicator driver circuit. If the passenger airbag
on/off switch is set to the Off position, the ACM turns
on the passenger airbag on/off switch Off indicator
and will internally disable the passenger airbag from
being deployed. The ACM also turns on the on/off
switch Off indicator for about seven seconds each
time the ignition switch is turned to the On position
as a bulb test. Following the bulb test, the ACM con-
trols the status of the Off indicator based upon the
Fig. 7 Airbag Control Module
1 - AIRBAG CONTROL MODULE
2 - ORIENTATION ARROW
3 - LABEL
4 - CONNECTOR RECEPTACLE (2)
DRRESTRAINTS 8O - 11

(1) Disconnect and isolate the battery negative
cable. Wait two minutes for the system capacitor to
discharge before further service.
(2) On models with a manual transmission,
remove the floor console from the top of the floor
panel transmission tunnel. (Refer to 23 - BODY/IN-
TERIOR/FLOOR CONSOLE - REMOVAL).
(3) On models with an automatic transmission,
remove the ACM cover from the instrument panel.
(Refer to 8 - ELECTRICAL/RESTRAINTS/ACM
COVER - REMOVAL).
(4) Reach through the rearward facing opening
below the instrument panel center stack support
bracket on the top of the floor panel transmission
tunnel to access and disconnect the two instrument
panel wire harness connectors for the Airbag Control
Module (ACM) from the ACM connector receptacles
located on the rearward facing side of the module
(Fig. 8). To disconnect the wire harness connectors
from the ACM, depress the release tab and lift the
lever arm on each connector.
(5) From the left side of the floor panel transmis-
sion tunnel, reach behind the module to access and
loosen the screw that secures the right side of the
ACM to the bracket on the floor panel transmission
tunnel. Loosen the screw about 7 millimeters (0.25
inch).
(6) From the left side of the floor panel transmis-
sion tunnel, remove the two screws that secure the
left side of the ACM to the bracket on the floor panel
transmission tunnel.
(7) Still working from the left side of the floor
panel transmission tunnel, lift the ACM upward far
enough to disengage the locating pin on the bottom ofthe ACM mounting flange from the locating hole in
the mounting bracket, then slide the ACM toward
the left far enough to disengage the slotted hole in
the right ACM mounting flange from under the head
of the previously loosened right mounting screw.
(8) Remove the ACM from the left side of the floor
panel transmission tunnel.
INSTALLATION
WARNING: TO AVOID PERSONAL INJURY OR DEATH,
ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE
THE SUPPLEMENTAL RESTRAINT SYSTEM BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, AIRBAG, SEAT BELT TENSIONER, IMPACT
SENSOR, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. DISCONNECT AND ISO-
LATE THE BATTERY NEGATIVE (GROUND) CABLE,
THEN WAIT TWO MINUTES FOR THE SYSTEM
CAPACITOR TO DISCHARGE BEFORE PERFORMING
FURTHER DIAGNOSIS OR SERVICE. THIS IS THE
ONLY SURE WAY TO DISABLE THE SUPPLEMENTAL
RESTRAINT SYSTEM. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT.
WARNING: TO AVOID PERSONAL INJURY OR DEATH,
NEVER STRIKE OR DROP THE AIRBAG CONTROL
MODULE, AS IT CAN DAMAGE THE IMPACT SENSOR
OR AFFECT ITS CALIBRATION. THE AIRBAG CON-
TROL MODULE CONTAINS THE IMPACT SENSOR,
WHICH ENABLES THE SYSTEM TO DEPLOY THE
SUPPLEMENTAL RESTRAINTS. IF AN AIRBAG CON-
TROL MODULE IS ACCIDENTALLY DROPPED DUR-
ING SERVICE, THE MODULE MUST BE SCRAPPED
AND REPLACED WITH A NEW UNIT. FAILURE TO
OBSERVE THIS WARNING COULD RESULT IN ACCI-
DENTAL, INCOMPLETE, OR IMPROPER SUPPLEMEN-
TAL RESTRAINT DEPLOYMENT.
(1) Position the Airbag Control Module (ACM) to
the left side of the floor panel transmission tunnel
near the ACM bracket (Fig. 8). When the ACM is cor-
rectly positioned, the arrow on the ACM label will be
pointed forward in the vehicle.
(2) From the left side of the floor panel transmis-
sion tunnel, slide the ACM toward the right far
enough to engage the slotted hole in the right ACM
mounting flange under the head of the previously
loosened right mounting screw, then engage the
locating pin on the bottom of the left ACM mounting
flange into the locating hole in the bracket.
(3) Still working from the left side of the floor
panel transmission tunnel, install and tighten the
two screws that secure the left ACM mounting
flanges to the bracket that is welded onto the floor
Fig. 8 Airbag Control Module Remove/Install
1 - AIRBAG CONTROL MODULE
2 - SCREW (3)
3 - BODY WIRE HARNESS CONNECTOR
4 - INSTRUMENT PANEL WIRE HARNESS CONNECTOR
5 - FLOOR PANEL TRANSMISSION TUNNEL
DRRESTRAINTS 8O - 13
AIRBAG CONTROL MODULE (Continued)

panel transmission tunnel. Tighten the screws to 12
N´m (9 ft. lbs.).
(4) From the left side of the floor panel transmis-
sion tunnel, reach behind the module to access and
tighten the screw that secures the right side of the
ACM to the bracket on the floor panel transmission
tunnel. Tighten the screw to 12 N´m (9 ft. lbs.).
(5) Reach through the rearward facing opening
below the instrument panel center stack support
bracket on the top of the floor panel transmission
tunnel to access and reconnect the two instrument
panel wire harness connectors for the ACM to the
ACM connector receptacle located on the rearward
facing side of the module. Be certain that the latches
on the connectors are each fully engaged.
(6) On models with an automatic transmission,
reinstall the ACM cover onto the instrument panel.
(Refer to 8 - ELECTRICAL/RESTRAINTS/ACM
COVER - INSTALLATION).
(7) On models with a manual transmission, rein-
stall the floor console onto the top of the floor panel
transmission tunnel. (Refer to 23 - BODY/INTERI-
OR/FLOOR CONSOLE - INSTALLATION).
(8) Do not reconnect the battery negative cable at
this time. The supplemental restraint system verifi-
cation test procedure should be performed following
service of any supplemental restraint system compo-
nent. (Refer to 8 - ELECTRICAL/RESTRAINTS -
STANDARD PROCEDURE - VERIFICATION TEST).
AUTOMATIC LOCKING
RETRACTOR
DESCRIPTION
The seat belt retractors used in all seating posi-
tions include an inertia-type, emergency locking
mechanism as standard equipment (Fig. 9). However,
the retractor locking mechanism for the passenger
side front seating position is mechanically switchable
from an emergency locking retractor to an automatic
locking retractor. The primary function of this fea-
ture is to securely accommodate a child seat in the
passenger side front seating position of the vehicle
without the need for a self-cinching seat belt tip half
latch plate unit or another supplemental device that
would be required to prevent the seat belt webbing
from unwinding freely from the retractor spool of an
inertia-type emergency locking retractor mechanism.
The automatic locking mechanism is integral to the
passenger side front seat belt and retractor unit and
is concealed beneath a molded plastic cover located
on the same side of the retractor spool as the seat
belt tensioner housing. The retractor is secured to
the inner B-pillar on the right side of the vehicle and
is concealed beneath the molded plastic inner B-pil-lar trim. The automatic locking mechanism cannot be
adjusted or repaired and, if faulty or damaged, the
entire passenger side front seat belt and retractor
unit must be replaced.
OPERATION
The automatic locking mode of the retractor is
engaged and the retractor is switched from operating
as a standard inertia-type emergency locking retrac-
tor by first buckling the combination lap and shoul-
der belt buckle. Then grasp the shoulder belt and
pull all of the webbing out of the retractor. Once all
of the belt webbing is extracted from the spool, the
retractor will automatically become engaged in the
pre-locked automatic locking mode and will make an
audible clicking or ratcheting sound as the shoulder
belt is allowed to retract to confirm that the auto-
matic locking mode is now engaged. Once the auto-
matic locking mode is engaged, the retractor will
remain locked and the belt will remain tight around
whatever it is restraining.
The retractor is returned to standard emergency
locking mode by unbuckling the combination lap and
shoulder belt buckle and allowing the belt webbing to
be almost fully retracted onto the retractor spool. The
emergency locking mode is confirmed by the absence
of the audible clicking or ratcheting sound as the belt
webbing retracts. This mode will allow the belt to
unwind from and wind onto the retractor spool freely
unless and until a predetermined inertia load is
sensed, or until the retractor is again switched to the
automatic locking mode.
Fig. 9 Automatic Locking Retractor
1 - TENSIONER HOUSING OR CHAMBER
2 - GAS GENERATOR
3 - TENSIONER PIGTAIL WIRE
4 - SPOOL
5 - TENSION REDUCER (DRIVER SIDE ON STANDARD CAB
ONLY)
6 - REDUCER CONNECTOR RECEPTACLE
7 - RETRACTOR LOCKING MECHANISM COVER
8O - 14 RESTRAINTSDR
AIRBAG CONTROL MODULE (Continued)

WARNING: TO AVOID PERSONAL INJURY OR
DEATH, ON VEHICLES EQUIPPED WITH AIRBAGS,
DISABLE THE SUPPLEMENTAL RESTRAINT SYS-
TEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, AIRBAG, SEAT BELT
TENSIONER, IMPACT SENSOR, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE.
DISCONNECT AND ISOLATE THE BATTERY NEGA-
TIVE (GROUND) CABLE, THEN WAIT TWO MINUTES
FOR THE SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE SUPPLEMENTAL RESTRAINT SYSTEM.
FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG DEPLOY-
MENT.
NOTE: Before starting this procedure, be certain
that the front wheels are still in the straight-ahead
position.
(1) While holding the centered clockspring rotor
and case stationary in relation to each other, care-
fully slide the clockspring down over the steering col-
umn upper shaft.
(2) Align and seat the hole in the locating tab at
the eleven o'clock position on the clockspring case
over the locating pin on the multi-function switch
mounting housing (Fig. 20).
(3) Install and tighten the two screws that secure
the clockspring to the multi-function switch mount-
ing housing. Tighten the screws to 2 N´m (20 in.
lbs.).
(4) Reconnect the two instrument panel wire har-
ness connectors for the clockspring to the two connec-
tor receptacles below the steering column on the back
of the clockspring housing.
(5) Position the lower shroud onto the steering col-
umn.
(6) From below the steering column, install and
tighten the one center screw that secures the lower
shroud to the steering column lock housing. Tighten
the screw to 2 N´m (20 in. lbs.).(7) Position the upper shroud onto the steering col-
umn. If the vehicle is equipped with an automatic
transmission, be certain to engage the gearshift lever
gap hider into the openings in the right side of the
upper and lower shrouds.
(8) Align the snap features on the upper shroud
with the receptacles on the lower shroud and apply
hand pressure to snap them together.
(9) From below the steering column, install and
tighten the two screws that secure the upper shroud
to the lower shroud. Tighten the screws to 2 N´m (20
in. lbs.).
(10) If the vehicle is equipped with the optional tilt
steering column, align the steering column tilt knob
with the tilt adjuster mechanism lever located on the
left side of the column just below the multi-function
switch control stalk and, using hand pressure, push
the knob firmly onto the lever.
(11) Reinstall the steering column opening cover
onto the instrument panel. (Refer to 23 - BODY/IN-
STRUMENT PANEL/STEERING COLUMN OPEN-
ING COVER - INSTALLATION).
(12) If a new clockspring has been installed,
remove the plastic locking pin that is securing the
clockspring rotor to the clockspring case to maintain
clockspring centering.
NOTE: When reinstalling the steering wheel, be cer-
tain to index the yellow rubber booted engagement
dowel on the upper surface of the clockspring rotor
between the two fins cast into the lower surface of
the steering wheel armature hub.
(13) Reinstall the steering wheel onto the steering
column. (Refer to 19 - STEERING/COLUMN/STEER-
ING WHEEL - INSTALLATION).
(14) Reconnect the steering wheel wire harness
connectors to the upper clockspring connector recep-
tacles. Be certain that the steering wheel wire har-
ness is routed between the steering wheel back trim
cover and the steering wheel armature.
(15) Reinstall the driver airbag onto the steering
wheel. (Refer to 8 - ELECTRICAL/RESTRAINTS/
DRIVER AIRBAG - INSTALLATION).
8O - 22 RESTRAINTSDR
CLOCKSPRING (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)