2002 DODGE RAM engine

DIAGNOSIS AND TESTING - HEADLAMP
A good ground is necessary for proper lighting
operation. Grounding is provided by the lamp socket
when it comes in contact with the metal body, or
through a separate ground wire.
Always begin any diagnosis by testing all of the
fuses and circuit breakers in the system. For com-plete circuit diagrams, refer to the appropriate wir-
ing information. The wiring information includes
wiring diagrams, proper wire and connector repair
procedures, details of wire harness routing and
retention, connector pin-out information and location
views for the various wire harness connectors, splices
and grounds.
CONDITION POSSIBLE CAUSES CORRECTION
HEADLAMPS ARE DIM
WITH ENGINE IDLING1. Loose or corroded battery cables. 1. Clean and secure battery cable clamps
and posts.
OR IGNITION TURNED
OFF2. Loose or worn generator drive
belt.2. Adjust or replace generator drive belt.
3. Charging system output too low. 3. Test and repair charging system.
4. Battery has insufficient charge. 4. Test battery state-of -charge.
5. Battery is sulfated or shorted. 5. Load test battery.
6. Poor lighting circuit Z3-ground. 6. Test for voltage drop across Z3-ground
locations.
7. Both headlamp bulbs defective. 7. Replace both headlamp bulbs.
HEADLAMP BULBS BURN
OUT1. Charging system output too high. 1. Test and repair charging system.
FREQUENTLY 2. Loose or corroded terminals or
splices in circuit.2. Inspect and repair all connectors and
splices.
HEADLAMPS ARE DIM
WITH ENGINE RUNNING1. Charging system output too low. 1. Test and repair charging system.
ABOVE IDLE* 2. Poor lighting circuit Z3-ground. 2. Test for voltage drop across Z3-ground
locations.
3. High resistance in headlamp
circuit.3. Test amperage draw of headlamp circuit.
4. Both headlamp bulbs defective. 4. Replace both headlamp bulbs.
HEADLAMPS FLASH
RANDOMLY1. Poor lighting circuit Z3-ground. 1. Test for voltage drop across Z3-ground
locations.
2. High resistance in headlamp
circuit.2. Test amperage draw of headlamp circuit.
Should not exceed 30 amps.
3. Faulty headlamps switch circuit
breaker.3. Replace headlamp switch.
4. Loose or corroded terminals or
splices in circuit.4. Inspect and repair all connectors and
splices.
HEADLAMPS (HIGH &
LOW) DO NOT
ILLUMINATE1. No voltage at either headlamp. 1. Voltage should always be present. Trace
short circuit and replace BOTH headlamp
fuses. Check wiring circuit from Right
headlamp fuse to headlamp. (Repeat for
Left side)
8L - 14 LAMPS/LIGHTING - EXTERIORBR/BE
HEADLAMP (Continued)

HEADLAMP RELAY
DESCRIPTION
The headlamp (or security) relay is located in the
Power Distribution Center (PDC) near the battery in
the engine compartment (Fig. 14). See the fuse and
relay layout label affixed to the inside surface of the
PDC cover for headlamp relay identification and loca-
tion. The headlamp relay is a conventional Interna-
tional Standards Organization (ISO) micro relay.
Relays conforming to the ISO specifications have
common physical dimensions, current capacities, ter-
minal patterns, and terminal functions. The relay is
contained within a small, rectangular, molded plastic
housing. The relay is connected to all of the required
inputs and outputs through its PDC receptacle by
five male spade-type terminals that extend from the
bottom of the relay base. The ISO designation for
each terminal is molded into the base adjacent to the
terminal. The ISO terminal designations are as fol-
lows:
²30 (Common Feed)- This terminal is con-
nected to the movable contact point of the relay.
²85 (Coil Ground)- This terminal is connected
to the ground feed side of the relay control coil.
²86 (Coil Battery)- This terminal is connected
to the battery feed side of the relay control coil.
²87 (Normally Open)- This terminal is con-
nected to the normally open fixed contact point of the
relay.
²87A (Normally Closed)- This terminal is con-
nected to the normally closed fixed contact point of
the relay.
The headlamp relay cannot be adjusted or
repaired. If the relay is damaged or faulty, it must be
replaced.
OPERATION
The headlamp (or security) relay is an electrome-
chanical switch that uses a low current input from
the high-line or premium Central Timer Module
(CTM) to control a high current output to the head-
lamps. The movable common feed contact point is
held against the fixed normally closed contact point
by spring pressure. When the relay coil is energized,
an electromagnetic field is produced by the coil wind-
ings. This electromagnetic field draws the movable
relay contact point away from the fixed normally
closed contact point, and holds it against the fixed
normally open contact point. When the relay coil is
de-energized, spring pressure returns the movable
contact point back against the fixed normally closed
contact point. A resistor or diode is connected in par-
allel with the relay coil in the relay, and helps to dis-
sipate voltage spikes and electromagnetic
interference that can be generated as the electromag-
netic field of the relay coil collapses.
The headlamp relay terminals are connected to the
vehicle electrical system through a connector recepta-
cle in the Power Distribution Center (PDC). The
inputs and outputs of the headlamp relay include:
²The common feed terminal (30) is connected to
ground at all times through a take out and eyelet
terminal connector of the right headlamp and dash
wire harness that is secured by a ground screw to
the left fender inner shield near the PDC in the
engine compartment.
²The coil ground terminal (85) is connected to the
Central Timer Module (CTM) through the security
relay control circuit. The CTM energizes the head-
lamp relay control coil by internally pulling this cir-
cuit to ground.
²The coil battery terminal (86) is connected to
battery current at all times through a fused B(+) cir-
cuit that is internal to the PDC.
²The normally open terminal (87) is connected to
the headlamps at all times through the beam select
switch low beam output circuit. This circuit provides
a path to ground for the headlamps through the com-
mon feed terminal when the headlamp relay control
coil is energized by the CTM.
²The normally closed terminal (87A) is not con-
nected to any circuit in this application, but is
grounded through the common feed terminal when
the headlamp relay control coil is de-energized.
The headlamp relay can be diagnosed using con-
ventional diagnostic tools and methods.
DIAGNOSIS AND TESTING - HEADLAMP RELAY
The headlamp (or security) relay (Fig. 15) is
located in the Power Distribution Center (PDC) near
the battery in the engine compartment. See the fuse
and relay layout label affixed to the inside surface of
Fig. 14 Power Distribution Center
1 - COVER
2 - POWER DISTRIBUTION CENTER
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 17

LAMPS/LIGHTING - INTERIOR
TABLE OF CONTENTS
page page
LAMPS/LIGHTING - INTERIOR
SPECIFICATIONS
INTERIOR LAMPS.....................33
DOME LAMP
REMOVAL.............................34
INSTALLATION.........................34
DOOR AJAR SWITCH
DESCRIPTION.........................34
DIAGNOSIS AND TESTING - DOOR AJAR
SWITCH............................34
REMOVAL.............................35
INSTALLATION.........................35GLOVE BOX LAMP AND SWITCH
REMOVAL.............................35
INSTALLATION.........................36
READING LAMP
DESCRIPTION.........................36
OPERATION...........................36
REMOVAL.............................36
INSTALLATION.........................37
VANITY LAMP
REMOVAL.............................37
INSTALLATION.........................37
LAMPS/LIGHTING - INTERIOR
SPECIFICATIONS
INTERIOR LAMPS
LAMP BULB
A/C HEATER CONTROL 158
ASH RECEIVER 161
CIGAR LIGHTER 161
HEADLAMP SWITCH 158
HEATER CONTROL 158
INSTRUMENT CLUSTER PC194
RADIO ASC
AIRBAG HIGH LINE PC194
AIRBAG LOW LINE PC74
ANTI-LOCK BRAKE PC74
BATTERY VOLTAGE PC194
BRAKE WARNING PC194LAMP BULB
CHECK ENGINE PC74
ENGINE OIL PRESSURE PC74
FOUR WHEEL DRIVE PC194
HIGH BEAM PC194
LOW FUEL PC194
LOW WASHER FLUID PC74
MAINTENANCE
REQUIREDPC74
MESSAGE CENTER PC194
SEAT BELT PC74
TURN SIGNAL PC194
UPSHIFT PC74
DOME 1004
GLOVE COMPARTMENT 1891
VANITY MIRROR LAMP P/N 6501966
BR/BELAMPS/LIGHTING - INTERIOR 8L - 33

using the U.S./Metric push button. The displayed
temperature is not an instant reading of conditions,
but an average temperature. It may take the ther-
mometer display several minutes to respond to a
major temperature change, such as driving out of a
heated garage into winter temperatures.
When the ignition switch is turned to the Off posi-
tion, the last displayed temperature reading stays in
the thermometer unit memory. When the ignition
switch is turned to the On position again, the ther-
mometer will display the memory temperature if the
engine coolant temperature is above about 43É C
(109É F). If the engine coolant temperature is below
about 43É C (109É F), the thermometer will display
the actual temperature sensed by the ambient tem-
perature sensor. The thermometer temperature dis-
play update interval varies with the vehicle speed;
therefore, if the temperature reading seems inaccu-
rate, drive the vehicle for at least three minutes
while maintaining a speed of 48 kilometers-per-hour
(30 miles-per-hour) or higher.
The thermometer function is supported by an
ambient temperature sensor. The sensor is mounted
outside the passenger compartment near the front
and center of the vehicle, and is hard wired to the
module. The ambient temperature sensor is available
as a separate service item.
STANDARD PROCEDURE
STANDARD PROCEDURE - COMPASS
CALIBRATION
CAUTION: Do not place any external magnets, such
as magnetic roof mount antennas, in the vicinity of
the compass. Do not use magnetic tools when ser-
vicing the overhead console.
The electronic compass unit features a self-cali-
brating design, which simplifies the calibration pro-
cedure. This feature automatically updates the
compass calibration while the vehicle is being driven.
This allows the compass unit to compensate for small
changes in the residual magnetism that the vehicle
may acquire during normal use. If the compass read-
ings appear to be erratic or out of calibration, per-
form the following calibration procedure. Also, new
service replacement compass mini-trip computer
modules must have their compass calibrated using
this procedure. Do not attempt to calibrate the com-
pass near large metal objects such as other vehicles,
large buildings, or bridges; or, near overhead or
underground power lines.
(1) Start the engine. If the compass/temperature
data is not currently being displayed, momentarily
depress and release the Step push button to stepthrough the display options until you have reached
the compass/temperature display.
(2) Depress both the U.S./Metric and the Step
push buttons at the same time for more than six sec-
onds, until ªCALº appears in the display, then release
both push buttons. The ªCALº in the display indi-
cates that the compass is in the calibration mode.
(3) Drive the vehicle on a level surface, at least
fifty feet away from large metal objects and power
lines, in all four compass directions, such as driving
around a city block several times or driving in two to
three complete circles at a slow to medium speed.
(4) When the calibration is successfully completed,
ªCALº will disappear from the display and normal
compass mini-trip computer operation will resume.
NOTE: If the ªCALº message remains in the display,
either there is excessive magnetism near the com-
pass, or the unit is faulty. Repeat the calibration
procedure at least one more time.
NOTE: If the wrong direction is still indicated in the
compass display, the area selected for calibration
may be too close to a strong magnetic field. Repeat
the calibration procedure in another location.
STANDARD PROCEDURE - COMPASS
VARIATION ADJUSTMENT
Compass variance, also known as magnetic decli-
nation, is the difference in angle between magnetic
north and true geographic north. In some geographic
locations, the difference between magnetic and geo-
graphic north is great enough to cause the compass
to give false readings. If this problem occurs, the
compass variance must be set. There are two meth-
ods that can be used to enter this information into
the compass mini-trip computer module. They are
the zone method and the direct method.
ZONE METHOD
(1) Using the Variance Settings map, find your
geographic location and note the zone number (Fig.
2).
(2) Turn the ignition switch to the On position. If
the compass/temperature data is not currently being
displayed, momentarily depress and release the Step
push button to step through the display options until
you have reached the compass/temperature display.
(3) Depress both the U.S./Metric and the Step
push buttons at the same time and hold them down
for more than 100 milliseconds, but not more than
one second. The compass mini-trip computer will
enter the variation adjustment mode and ªVARº
along with the current variance zone will appear in
the display.
8M - 4 MESSAGE SYSTEMSBR/BE
OVERHEAD CONSOLE (Continued)

AMBIENT TEMP SENSOR
DESCRIPTION
Ambient air temperature is monitored by the com-
pass mini-trip computer module through the ambient
temperature sensor. The ambient temperature sensor
is a variable resistor mounted to a bracket that is
secured with a screw to the underside of the hood
panel near the hood latch striker in the engine com-
partment (Fig. 8).
For complete circuit diagrams, refer toOverhead
Consolein the Contents of Wiring Diagrams. The
ambient temperature sensor cannot be adjusted or
repaired and, if faulty or damaged, it must be
replaced.
OPERATION
The ambient temperature sensor is a variable
resistor that operates on a five-volt reference signal
sent to it by the compass mini-trip computer module.
The resistance in the sensor changes as temperature
changes, changing the return circuit voltage to the
compass mini-trip computer module. Based upon the
resistance in the sensor, the compass mini-trip com-
puter module senses a specific voltage on the return
circuit, which it is programmed to correspond to a
specific temperature.
DIAGNOSIS AND TESTING - AMBIENT
TEMPERATURE SENSOR
The thermometer function is supported by the
ambient temperature sensor, a wiring circuit, and a
portion of the compass mini-trip computer module. If
any portion of the ambient temperature sensor cir-
cuit fails, the compass/thermometer display function
will self-diagnose the circuit. If 55É C (131É F)
appears in the display, the sensor is being exposed to
temperatures above 55É C (131É F), or the sensor cir-
cuit is shorted. If ±40É C (±40É F) appears in the dis-
play, the sensor is being exposed to temperatures
below ±40É C (±40É F), or the sensor circuit is open.
The ambient temperature sensor circuit can also be
diagnosed using the following Sensor Test, and Sen-
sor Circuit Test. If the temperature sensor and cir-
cuit are confirmed to be OK, but the temperature
display is inoperative or incorrect, refer toDiagnosis
and Testing the Compass Mini-Trip Computer.
For complete circuit diagrams, refer toWiring Dia-
grams.
SENSOR TEST
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the ambient temperature sensor wire har-
ness connector.(2) Measure the resistance of the ambient temper-
ature sensor. At ±40É C (±40É F), the sensor resis-
tance is 336 kilohms. At 55É C (131É F), the sensor
resistance is 2.488 kilohms. The sensor resistance
should read between these two values. If OK, refer to
theSensor Circuit Test below. If not OK, replace
the faulty ambient temperature sensor.
SENSOR CIRCUIT TEST
(1) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Disconnect the ambient temperature sensor wire har-
ness connector and the overhead console wire har-
ness connector.
(2) Connect a jumper wire between the two termi-
nals in the body half of the ambient temperature sen-
sor wire harness connector.
(3) Check for continuity between the sensor return
circuit and the ambient temperature sensor signal
circuit cavities of the roof wire harness overhead con-
sole connector. There should be continuity. If OK, go
to Step 4. If not OK, repair the open sensor return
circuit or ambient temperature sensor signal circuit
to the ambient temperature sensor as required.
(4) Remove the jumper wire from the body half of
the ambient temperature sensor wire harness con-
nector. Check for continuity between the sensor
return circuit cavity of the roof wire harness over-
head console connector and a good ground. There
should be no continuity. If OK, go to Step 5. If not
OK, repair the shorted sensor return circuit as
required.
(5) Check for continuity between the ambient tem-
perature sensor signal circuit cavity of the roof wire
harness overhead console connector and a good
ground. There should be no continuity. If OK, refer to
Diagnosis and Testing the Compass Mini-Trip
Computerin this section. If not OK, repair the
shorted ambient temperature sensor signal circuit as
required.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Locate the ambient temperature sensor, on the
underside of the hood near the hood latch striker
(Fig. 8).
(3) Disconnect the wire harness connector from the
ambient temperature sensor connector receptacle.
(4) Remove the one screw that secures the ambient
temperature sensor bracket to the inner hood rein-
forcement.
(5) Remove the ambient temperature sensor from
the inner hood reinforcement.
8M - 12 MESSAGE SYSTEMSBR/BE

fault or malfunction. Refer to the appropriate diag-
nostic information to diagnose the problem.
SPECIAL TOOLS - AIRBAG SYSTEM
AIRBAG CONTROL MODULE
DESCRIPTION
The Airbag Control Module (ACM) is concealed
underneath the plastic ACM trim cover (automatic
transmission) or center console (manual transmis-
sion), directly below the instrument panel in the pas-
senger compartment of the vehicle. The ACM is
secured with screws to a stamped steel mounting
bracket located under the instrument panel center
support bracket on the floor panel transmission tun-
nel. The ACM contains an electronic microprocessor,
an electronic impact sensor, an electromechanical saf-
ing sensor, and an energy storage capacitor. TheACM is connected to the vehicle electrical system
through a take out and connector of the instrument
panel wire harness.
The ACM cannot be repaired or adjusted and, if
damaged or faulty, it must be replaced.
OPERATION
The microprocessor in the ACM contains the airbag
system logic circuits, and it monitors and controls all
of the airbag system components. The ACM also uses
On-Board Diagnostics (OBD) and can communicate
with other electronic modules in the vehicle as well
as with the DRBIIItscan tool using the Chrysler
Collision Detection (CCD) data bus network. This
method of communication is used for control of the
airbag indicator in the ElectroMechanical Instrument
Cluster (EMIC) and for airbag system diagnosis and
testing through the 16-way data link connector
located on the lower left edge of the instrument
panel. (Refer to 8 - ELECTRICAL/ELECTRONIC
CONTROL MODULES/COMMUNICATION - OPER-
ATION). The ACM microprocessor continuously mon-
itors all of the airbag system electrical circuits to
determine the system readiness. If the ACM detects
a monitored system fault, it sets an active Diagnostic
Trouble Code (DTC) and sends messages to the
EMIC over the CCD data bus to turn on the airbag
indicator. (Refer to 8 - ELECTRICAL/INSTRUMENT
CLUSTER/AIRBAG INDICATOR - OPERATION). If
the airbag system fault is still present when the igni-
tion switch is turned to the Off position, the DTC is
stored in memory by the ACM. However, if a fault
does not recur for a number of ignition cycles, the
ACM will automatically erase the stored DTC.
The ACM receives battery current through two cir-
cuits, on a fused ignition switch output (run) circuit
through a fuse in the Junction Block (JB), and on a
fused ignition switch output (start-run) circuit
through a second fuse in the JB. The ACM is
grounded through a ground circuit and take out of
the instrument panel wire harness. This take out has
a single eyelet terminal connector secured by a nut to
a ground stud located on the forward extension of the
left front fender wheel housing in the engine com-
partment. Therefore, the ACM is operational when-
ever the ignition switch is in the Start or On
positions. The ACM also contains an energy-storage
capacitor. When the ignition switch is in the Start or
On positions, this capacitor is continually being
charged with enough electrical energy to deploy the
airbags for up to one second following a battery dis-
connect or failure. The purpose of the capacitor is to
provide backup airbag system protection in case
there is a loss of battery current supply to the ACM
during an impact. The capacitor is only serviced as a
unit with the ACM.
Fig. 4 16-Way Data Link Connector - Typical
1 - 16±WAY DATA LINK CONNECTOR
2 - BOTTOM OF INSTRUMENT PANEL
Puller C-3428-B
8O - 6 RESTRAINTSBR/BE
RESTRAINTS (Continued)

SPEED CONTROL
TABLE OF CONTENTS
page page
SPEED CONTROL
DESCRIPTION
DESCRIPTION - SPEED CONTROL SYSTEM . 1
DESCRIPTION - VEHICLE SPEED INPUT....2
OPERATION - SPEED CONTROL SYSTEM....2
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - VACUUM
SUPPLY TEST.........................3
DIAGNOSIS AND TESTING - ROAD TEST....4
SPECIFICATIONS
TORQUE - SPEED CONTROL SYSTEM.....4
CABLE
DESCRIPTION..........................4
OPERATION............................4
REMOVAL
REMOVAL - GAS ENGINES...............4
REMOVAL - DIESEL WITH AUTO. TRANS. . . . 5
INSTALLATION
INSTALLATION - GAS ENGINES...........5
INSTALLATION - DIESEL WITH AUTO.
TRANS...............................6SPEED CONTROL SERVO
DESCRIPTION..........................6
OPERATION............................6
REMOVAL
REMOVAL............................6
REMOVAL - DIESEL WITH AUTO. TRANS. . . . 9
INSTALLATION
INSTALLATION.......................11
INSTALLATION - DIESEL WITH AUTO.
TRANS..............................12
SWITCH
DESCRIPTION.........................12
OPERATION...........................12
REMOVAL.............................13
INSTALLATION.........................14
VACUUM RESERVOIR
DESCRIPTION.........................14
REMOVAL.............................14
INSTALLATION.........................15
SPEED CONTROL
DESCRIPTION
DESCRIPTION - SPEED CONTROL SYSTEM
Gas Engines and/or Diesel With Automatic Trans.
The speed control system is operated by the use of
a cable and a vacuum controlled servo. Electronic
control of the speed control system is integrated into
the Powertrain Control Module (PCM). 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 THATARE WINDING, ICY, SNOW COVERED, OR SLIP-
PERY.
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.
BR/BESPEED CONTROL 8P - 1

DESCRIPTION - VEHICLE SPEED INPUT
Gas Engines and/or Diesel With Automatic Trans.
The Vehicle Speed Sensor (VSS) is no longer used
for any Dodge Truck.
Vehicle speed and distance covered are measured
by the Rear Wheel Speed Sensor. The sensor is
mounted to the rear axle. A signal is sent from this
sensor to the Controller Antilock Brake (CAB) com-
puter. A signal is then sent from the CAB to the Pow-
ertrain Control Module (PCM) to determine vehicle
speed and distance covered. The PCM will then
determine strategies for speed control system opera-
tion.
Diesel With Manual Trans.
The Vehicle Speed Sensor (VSS) is no longer used
for any Dodge Truck.
Vehicle speed and distance covered are measured
by the Rear Wheel Speed Sensor. The sensor is
mounted to the rear axle. A signal is sent from this
sensor to the Controller Antilock Brake (CAB) com-
puter. A signal is then sent from the CAB to the
Engine Control Module (ECM) to determine vehicle
speed and distance covered. The ECM will then
determine strategies for speed control system opera-
tion.
OPERATION - SPEED CONTROL SYSTEM
Gas Engines and/or Diesel With Automatic Trans.
When speed control is selected by depressing the
ON switch, the PCM allows a set speed to be stored
in PCM 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 selector be indicating the
transmission is in Park or Neutral.
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.
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 of rpm (indication 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.
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 when the RES/ACCEL is released. The PCM
also has a9tap-up9feature in which vehicle speed
increases at a rate of approximately 2 mph for each
momentary switch activation of the RES/ACCEL
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.
Diesel With Manual Trans.
When speed control is selected by depressing the
ON switch, the Engine Control Module (ECM) allows
a set speed to be stored in ECM RAM for speed con-
trol. 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.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.
NOTE: Depressing the OFF switch or turning off the
ignition switch will erase the set speed stored in
the ECM.
For added safety, the speed control system is pro-
grammed to disengage for any of the following condi-
tions:
²A rapid increase of rpm (indication 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).
8P - 2 SPEED CONTROLBR/BE
SPEED CONTROL (Continued)