1998 DODGE RAM 1500 air condition

retracted or extracted is a sure indication that the
seat belt tensioner has been deployed and requires
replacement. (Refer to 8 - ELECTRICAL/RE-
STRAINTS/FRONT OUTBOARD SEAT BELT &
RETRACTOR - REMOVAL).
OPERATION
The seat belt tensioners are deployed by a signal
generated by the Airbag Control Module (ACM)
through the driver and passenger seat belt tensioner
line 1 and line 2 (or squib) circuits. When the ACM
sends the proper electrical signal to the tensioners,
the electrical energy generates enough heat to ini-
tiate a small pyrotechnic gas generator. The gas gen-
erator is installed at the top of the tensioner housing
which contains a long metal tape that is routed
through two chambers within the housing. Each end
of the tape is wound around the outer sleeve of a
mechanical clutch mechanism secured to one end of
the torsion bar upon which the retractor spool is
secured. As the gas expands, it is directed against
the metal tape within the two chambers of the hous-
ing causing the tape to unwind from the clutch
sleeve. As the clutch rotates it engages the torsion
bar, which drives the seat belt retractor spool causing
the slack to be removed from the seat belt.
Once a seat belt tensioning sequence has been
completed, the forward momentum of the occupant
results in deformation of the torsion bar. As the tor-
sion bar deforms it allows the seat belt webbing to
unwind from the retractor spool, which causes the
metal tape to be wound back onto the clutch sleeve
until it is pulled tight against two cutter blades
within the housing, which immediately cut the metal
tape.
Removing excess slack from the seat belt not only
keeps the occupant properly positioned for an airbag
deployment following a frontal impact of the vehicle,
but also helps to reduce injuries that the occupant
might experience in these situations as a result of a
harmful contact with the steering wheel, steering col-
umn, instrument panel and/or windshield. The tor-
sion bar is designed to deform in order to control the
loading being applied to the occupant by the seat belt
during a frontal impact, further reducing the poten-
tial for occupant injuries.
The ACM monitors the condition of the seat belt
tensioners through circuit resistance. The ACM will
illuminate the airbag indicator in the ElectroMe-
chanical Instrument Cluster (EMIC) and store a
Diagnostic Trouble Code (DTC) for any fault that is
detected. For proper diagnosis of the seat belt ten-
sioners, a DRBIIItscan tool is required. Refer to the
appropriate diagnostic information.
SEAT BELT TENSION
REDUCER
DESCRIPTION
A seat belt tension reducer is standard equipment
for the driver side front outboard seat belt on stan-
dard cab versions of this model (Fig. 49). The tension
reducer is integral to the driver side front outboard
seat belt and retractor unit, which is secured to the
inner B-pillar on the left side of the vehicle. The
retractor is concealed beneath the molded plastic
inner B-pillar trim. The seat belt tension reducer
consists primarily of a 12-volt Direct Current (DC)
solenoid and an integral connector receptacle that is
located on the forward facing end housing of the
retractor. The seat belt tension reducer is controlled
by a battery current output of the ignition switch and
a ground path provided by the seat belt switch, and
is connected to the vehicle electrical system through
a dedicated take out of the body wire harness by a
keyed and latching molded plastic connector insula-
tor to ensure a secure connection.
The seat belt tension reducer cannot be repaired
and, if faulty or damaged, the entire driver side front
outboard seat belt and retractor unit must be
replaced. (Refer to 8 - ELECTRICAL/RESTRAINTS/
FRONT OUTBOARD SEAT BELT & RETRACTOR -
REMOVAL).
Fig. 49 Seat Belt Tension Reducer
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
DRRESTRAINTS 8O - 53
SEAT BELT TENSIONER (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)

(11) Before starting engine, operate accelerator
pedal to check for any binding.
SWITCH
DESCRIPTION
Two separate switch pods operate the speed control
system. The steering-wheel-mounted switches use
multiplexed circuits to provide inputs to the PCM (to
the ECM for diesel) for ON, OFF, RESUME, ACCEL-
ERATE, SET, DECEL and CANCEL modes. Refer to
the owner's manual for more information on speed
control switch functions and setting procedures.
The individual switches cannot be repaired. If one
switch fails, the entire switch module must be
replaced.
Depending on engine control computer (JTEC
having a 3± plug connector or NGC having a 4±
plug connector), 2 types of switches are used.
Both types of switches are internally and exter-
nally different. The switch used with the NGC
system has an attached pigtail lead. The switch
used with the JTEC system does not have an
attached pigtail lead.
OPERATION
When speed control is selected by depressing the
ON, OFF switch, the PCM(ECM for diesel)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 approxi-
mately 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.
The speed control can be disengaged also by any of
the following conditions:
²An indication of Park or Neutral (auto. trans.)
²The VSS signal increases at a rate of 10 mph
per second (indicates that the co-efficient of friction
between the road surface and tires is extremely low)
²Depressing the clutch pedal (manual trans.).
²Excessive engine rpm (indicates that the trans-
mission may be in a low gear)
²The VSS signal decreases at a rate of 10 mph
per second (indicates that the vehicle may have
decelerated at an extremely high rate)
²If the actual speed is not within 20 mph of the
set speed
Fig. 6 SPEED CONTROL SERVO LOCATION
1 - BATTERY TRAY
2 - MOUNTING LUGS
3 - SERVO
4 - ELEC. CONNEC.
5 - MOUNTING SCREWS (3)
6 - MOUNTING BRACKET
7 - VACUUM LINE
Fig. 7 SERVO CABLE CLIP REMOVE/INSTALL Ð
TYPICAL
1 - SERVO MOUNTING NUTS (2)
2 - SERVO
3 - CABLE RETAINING CLIP
4 - SERVO CABLE AND SLEEVE
DRSPEED CONTROL 8P - 7
SERVO (Continued)

VACUUM RESERVOIR
DESCRIPTION
The vacuum reservoir is a plastic storage tank con-
nected to an engine vacuum source by vacuum lines.
A vacuum reservoir is not used with diesel engines or
the 5.7L gas powered engine.
OPERATION
The vacuum reservoir is used to supply the vac-
uum needed to maintain proper speed control opera-
tion when engine vacuum drops, such as in climbing
a grade while driving. A one-way check valve is used
in the vacuum line between the reservoir and the
vacuum source. This check valve is used to trap
engine vacuum in the reservoir. On certain vehicle
applications, this reservoir is shared with the heat-
ing/air-conditioning system. The vacuum reservoir
cannot be repaired and must be replaced if faulty.
DIAGNOSIS AND TESTING - VACUUM
RESERVOIR
(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.
(5) Verify operation of one-way check valve and
check it for leaks.Certain models may be
equipped with 2 check-valves.
(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.
REMOVAL
The vacuum reservoir is located in the engine com-
partment under the fresh air cowl grill panel (Fig.
10).
(1) Remove wiper blades and arms. Refer to Wiper
Arm Removal / Installation in the Wipers / Washers
section.
(2) Remove fresh air cowl grill. Refer to Cowl Grill
Removal / Installation.
(3) Disconnect vacuum line at reservoir (Fig. 11).
(4) Remove 2 reservoir mounting nuts (Fig. 11).
(5) Remove reservoir from cowl.
Fig. 10 VACUUM RESERVOIR LOCATION
1 - COWL GRILL
2 - WIPER ARMS / BLADES
3 - VACUUM RESERVOIR
DRSPEED CONTROL 8P - 9

SKIM cannot be repaired and, if faulty or damaged,
the unit must be replaced.
DIAGNOSIS AND TESTING
VEHICLE THEFT SECURITY SYSTEM
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO RESTRAINT SYSTEMS BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING
COLUMN, OR INSTRUMENT PANEL COMPONENT
DIAGNOSIS OR SERVICE. FAILURE TO TAKE THE
PROPER PRECAUTIONS COULD RESULT IN ACCI-
DENTAL AIRBAG DEPLOYMENT AND POSSIBLE
PERSONAL INJURY.
NOTE: The most reliable, efficient, and accurate
means to diagnose the Vehicle Theft Security Sys-
tem (VTSS) and Sentry Key Immobilizer System
(SKIS) involves the use of a DRBlllTscan tool and
the proper Powertrain Diagnostic Procedures man-
ual.
The Vehicle Theft Security System (VTSS), Sentry
Key Immobilizer System (SKIS) and the Programma-
ble Communication Interface (PCI) bus network
should be diagnosed using a DRBIIItscan tool. The
DRBIIItwill allow confirmation that the PCI bus is
functional, that the Sentry Key Immobilizer Module
(SKIM) is placing the proper messages on the PCI
bus, and that the Powertrain Control Module (PCM)
and the Instrument Cluster are receiving the PCI
bus messages. Refer to the proper Powertrain or
Body Diagnostic Procedures manual.
Visually inspect the related wiring harness connec-
tors. Look for broken, bent, pushed out or corroded
terminals. If any of the conditions are present, repair
as necessary. Refer to Wiring Diagrams for complete
circuit descriptions and diagrams. Refer to 8 - ELEC-
TRICAL/ELECTRONIC CONTROL MODULES/SEN-
TRY KEY IMMOBILIZER MODULE - REMOVAL for
SKIM replacement.
STANDARD PROCEDURE
CONFIGURING A NEW MODULE / SWITCH
OPERATING MODES
To configure a new module or to switch operating
modes, a DRBIIItscan tool must be used.
(1) Hook up the DRBIIItscan tool to the Data
Link Connector (DLC).
(2) With the key in the ignition, turn the key to
the RUN position.(3) After the DRBIIItscan tool initialization, per-
form the following:
(a) Select ªTheft Alarm.º
(b) Select ªVTSS.º
(c) Select ªMiscellaneous.º
(4) Once in the ªMiscellaneousº screen:
(a) If you wish to configure a new module, select
ªConfigure Module.º
(b) If you wish to put the module into customer
usage mode, select ªEnable VTSS.º
(c) If you wish to put the module into dealer lot
mode, select ªDealer Lot.º
SENTRY KEY IMMOBILIZER SYSTEM
INITIALIZATION
The Sentry Key Immobilizer System (SKIS) initial-
ization should be performed following a Sentry Key
Immobilizer Module (SKIM) replacement.
It can be summarized by the following:
(1) Obtain the vehicles unique PIN number
assigned to it's original SKIM from the vehicle
owner, the vehicle's invoice or from Chrysler's Cus-
tomer Center.
(2) With the DRBIIItscan tool, select ªTheft
Alarm,º ªSKIM,º Miscellaneous.º Select ªSKIM Mod-
ule Replacedº function and the DRBIIItwill prompt
you through the following steps.
(3) Enter secured access mode using the unique
four digit PIN number.
(4) Program the vehicle's VIN number into the
SKIM's memory.
(5) Program the country code into the SKIM's
memory (U.S.).
(6) Transfer the vehicle's unique Secret Key data
from the PCM. This process will require the SKIM to
be insecured access mode. The PIN number must
be entered into the DRBIIItbefore the SKIM will
entersecured access mode. Oncesecured access
modeis active, the SKIM will remain in that mode
for 60 seconds.
(7) Program all customer keys into the SKIM's
memory. This required that the SKIM be insecured
access modeThe SKIM will immediately exit
secured access modeafter each key is pro-
grammed.
NOTE: If a PCM is replaced, the unique ªSecret
Keyº data must be transferred from the SKIM to the
PCM. This procedure requires the SKIM to be
placed in SECURED ACCESS MODE using the four
digit PIN code.
DRVEHICLE THEFT SECURITY 8Q - 3
VEHICLE THEFT SECURITY (Continued)

washer system plumbing (Fig. 3). The check valve is
integral to the washer nozzle plumbing wye fitting
located in the cowl plenum area beneath the cowl
plenum cover/grille panel near the base of the wind-
shield. The check valve consists of a molded plastic
body with a raised arrowhead molded into its center
section that indicates the direction of the flow
through the valve, and three barbed hose nipples
formed in a wye configuration on the outside circum-
ference of the center section of the valve body. The
check valve cannot be adjusted or repaired and, if
faulty or damaged, it must be replaced.
OPERATION
The check valve provides more than one function
in this application. It serves as a wye connector fit-
ting between the engine compartment and washer
nozzle sections of the washer supply hose. It prevents
washer fluid from draining out of the washer supply
hoses back to the washer reservoir. This drain-back
would result in a lengthy delay from when the
washer switch is actuated until washer fluid was dis-
pensed through the washer nozzles, because the
washer pump would have to refill the washer plumb-
ing from the reservoir to the nozzles. Such a drain-
back condition could also result in water, dirt, or
other outside contaminants being siphoned into the
washer system through the washer nozzle orifice.
This water could subsequently freeze and plug the
nozzle, while other contaminants could interfere with
proper nozzle operation and cause improper nozzle
spray patterns. In addition, the check valve prevents
washer fluid from siphoning through the washer noz-
zles after the washer system is turned Off.When the washer pump pressurizes and pumps
washer fluid from the reservoir through the washer
plumbing, the fluid pressure unseats a diaphragm
from over a sump well within the valve by overriding
the spring pressure applied to it by a piston (Fig. 4).
With the diaphragm unseated, washer fluid is
allowed to flow toward the two washer nozzles. When
the washer pump stops operating, the spring pres-
sure on the piston seats the diaphragm over the
sump well in the valve and fluid flow in either direc-
tion within the washer plumbing is prevented. The
check valve cannot be adjusted or repaired and, if
faulty or damaged, it must be replaced.REMOVAL
(1) Remove both wiper arms from the wiper pivots.
(Refer to 8 - ELECTRICAL/WIPERS/WASHERS/
WIPER ARM - REMOVAL).
(2) Unlatch and open the hood.
(3) Remove the cowl plenum cover/grille panel
from over the cowl plenum. (Refer to 23 - BODY/EX-
TERIOR/COWL GRILLE - REMOVAL).
(4) From the underside of the cowl plenum cover/
grille panel, disconnect the cowl plenum and washer
nozzle hoses from the three barbed nipples of the
check valve (Fig. 5).
(5) Remove the check valve from the underside of
the cowl plenum cover/grille panel.
INSTALLATION
(1) Position the check valve to the underside of the
cowl plenum cover/grille panel (Fig. 5). Be certain
that the flow direction arrow molded into the check
valve body is oriented towards the washer nozzles.
Fig. 3 Check Valve
1 - INLET NIPPLE
2 - CHECK VALVE
3 - OUTLET NIPPLE (2)
4 - FLOW DIRECTION ARROW
Fig. 4 Check Valve
1 - SPRING
2 - PISTON
3 - DIAPHRAGM
4 - TO WASHER NOZZLE
5 - FROM WASHER PUMP
8R - 8 WIPERS/WASHERSDR
CHECK VALVE (Continued)

WIRING
TABLE OF CONTENTS
page page
WIRING DIAGRAM INFORMATION....... 8W-01-1
COMPONENT INDEX.................. 8W-02-1
POWER DISTRIBUTION............... 8W-10-1
GROUND DISTRIBUTION.............. 8W-15-1
BUS COMMUNICATIONS.............. 8W-18-1
CHARGING SYSTEM.................. 8W-20-1
STARTING SYSTEM.................. 8W-21-1
FUEL/IGNITION SYSTEM.............. 8W-30-1
TRANSMISSION CONTROL SYSTEM..... 8W-31-1
VEHICLE SPEED CONTROL............ 8W-33-1
REAR WHEEL ANTILOCK BRAKES....... 8W-34-1
ALL WHEEL ANTILOCK BRAKES........ 8W-35-1
VEHICLE THEFT SECURITY SYSTEM..... 8W-39-1
INSTRUMENT CLUSTER............... 8W-40-1
HORN/CIGAR LIGHTER/POWER OUTLET . . 8W-41-1
AIR CONDITIONING.................. 8W-42-1
AIRBAG SYSTEM.................... 8W-43-1
INTERIOR LIGHTING.................. 8W-44-1AUDIO SYSTEM..................... 8W-47-1
REAR WINDOW DEFOGGER............ 8W-48-1
OVERHEAD CONSOLE................. 8W-49-1
FRONT LIGHTING.................... 8W-50-1
REAR LIGHTING..................... 8W-51-1
TURN SIGNALS...................... 8W-52-1
WIPERS............................ 8W-53-1
TRAILER TOW....................... 8W-54-1
NAVIGATION/TELECOMMUNICATION..... 8W-55-1
POWER WINDOWS................... 8W-60-1
POWER DOOR LOCKS................ 8W-61-1
POWER MIRRORS................... 8W-62-1
POWER SEATS...................... 8W-63-1
SPLICE INFORMATION................ 8W-70-1
CONNECTOR PIN-OUTS............... 8W-80-1
CONNECTOR/GROUND/SPLICE
LOCATION........................ 8W-91-1
POWER DISTRIBUTION............... 8W-97-1 DRWIRING 8W - 1

8W-42 AIR CONDITIONING
Component Page
A/C Compressor Clutch............... 8W-42-7
A/C Compressor Clutch Relay.......... 8W-42-7
A/C Pressure Transducer............ 8W-42-8, 9
A/C-Heater Control........... 8W-42-2, 3, 4, 5, 6
Blend Door Actuator.................. 8W-42-6
Blower Motor....................... 8W-42-2
Blower Motor Resistor Block........... 8W-42-2
Condenser Fan..................... 8W-42-10
Condenser Fan Relay................ 8W-42-10
Data Link Connector............. 8W-42-3, 4, 8
Driver Blend Door Actuator............ 8W-42-5
Engine Control Module.............. 8W-42-7, 9
EVAPorator Temperature Sensor........ 8W-42-4
Fuse 12........................... 8W-42-10
Fuse 16............................ 8W-42-7Component Page
Fuse 36.......................... 8W-42-3, 4
G104............................. 8W-42-10
G107.............................. 8W-42-7
G120.............................. 8W-42-7
G202.......................... 8W-42-2, 3, 4
Heated Mirror Relay............... 8W-42-3, 4
Ignition Switch...................... 8W-42-2
Instrument Cluster................... 8W-42-2
Integrated Power Module....... 8W-42-3, 4, 7, 10
Mode Door Actuator 1............... 8W-42-5, 6
Mode Door Actuator 2............... 8W-42-5, 6
Passenger Blend Door Actuator......... 8W-42-5
Powertrain Control Module........ 8W-42-7, 8, 10
PTCNo.1.......................... 8W-42-7
Recirculation Door Actuator.......... 8W-42-5, 6
DR8W-42 AIR CONDITIONING 8W - 42 - 1