heating DODGE RAM 2002 Service Service Manual

(2) Connect the new heating element electrical
connectors (Fig. 12) .
(3) Connect the negative battery cable.
(4) Verify heated seat system operation.
(5) Install the appropriate seat cushion or seat
back trim cover. Make certain the seat wire harness
is correctly routed through the seat and seat back.
The excess wire between the cushion and back ele-
ments should be securely tucked between the rear of
the cushion foam and the rear carpet flap of the trim
cover. (Fig. 13).
HEATED SEAT RELAY
DESCRIPTION
The heated seat relay is an electromechanical device
that switches battery current to the heated seat module
when the relay control coil is energized. The heated seat
relay is located in the Junction Block (JB), on the left
end of the instrument panel in the passenger compart-
ment (Fig. 14). The heated seat relay is a International
Standards Organization (ISO) micro-relay. Relays con-
forming to the ISO specifications have common physical
dimensions, current capacities, terminal patterns, and
terminal functions. The ISO micro-relay terminal func-
tions are the same as a conventional ISO relay. How-
ever, the ISO micro-relay terminal pattern (or footprint)
is different, the current capacity is lower, and the phys-
Fig. 12 HEATING ELEMENT INSTALLED
1 - SEAT BACK WIRE HARNESS
2 - HEATED SEAT WIRE HARNESS CONNECTOR
3 - HEATED SEAT CUSHION ELEMENT
Fig. 13 HEATED SEAT WIRE HARNESS ROUTING
1 - SEAT BACK HEATED SEAT WIRE HARNESS
2 - PASSENGER SEAT BACK
3 - SEAT BACK ELEMENT CONNECTOR
4 - SEAT CUSHION ELEMENT CONNECTOR
Fig. 14 Heated Seat Relay
1 - JUNCTION BLOCK
2 - HEATED SEAT RELAY
3 - INSTRUMENT PANEL
4 - COMBINATION FLASHER
8G - 14 HEATED SEAT SYSTEMBR/BE
HEATED SEAT ELEMENT (Continued)

the front seat passenger can select a preferred level
of seat heating. Each heated seat switch has two
Light-Emitting Diode (LED) indicator lamps, which
indicate the selected mode (Low or High) of the seat
heater. These indicator lamps also provide diagnostic
feedback for the heated seat system. Each switch
also has an incandescent bulb, which provides dim-
mer controlled back lighting of the switch when the
headlamps or park lamps are on.
The two LED indicator lamps and the incandescent
bulb in each heated seat switch cannot be repaired. If
the indicator lamps or back lighting bulb are faulty
or damaged, the individual heated seat switch must
be replaced.
OPERATION
The heated seat switches receive battery current
through a fused ignition switch output (run) circuit
when the ignition switch is in the On position.
Depressing the heated seat switch rocker to its
momentary High or Low position provides a hard-
wired resistor multiplexed voltage request signal to
the heated seat module to power the heated seat ele-
ment of the selected seat and maintain the requested
temperature setting. If the heated seat switch is
depressed to a different position (Low or High) than
the currently selected state, the heated seat module
will change states to support the new selection. If a
heated seat switch is depressed a second time to thesame position as the currently selected state, the
heated seat module interprets the second input as a
request to turn the seat heater off. The heated seat
module will then turn the heated seat elements for
that seat off.
The indicator lamps in the heated seat switches
receive battery current through a fused ignition
switch output (run) circuit when the ignition switch
is in the On position. The ground side of each indi-
cator lamp is controlled by a separate (high or low/
driver or passenger) indicator lamp driver circuit by
the heated seat module. The heated seat module con-
trol of the switch indicator lamps also allows the
module to provide diagnostic feedback to the vehicle
operator to indicate monitored heated seat system
faults by flashing the indicator lamps on and off. One
side of the incandescent back lighting bulb in each
heated seat switch is connected to ground at all
times. The other side of the incandescent bulb is con-
nected to the fused panel lamps dimmer switch sig-
nal circuit. These bulbs are energized when the park
lamps or headlamps are turned on, and their illumi-
nation intensity is controlled by the panel lamps dim-
mer switch.
DIAGNOSIS AND TESTING - HEATED SEAT
SWITCH
Refer toWiring Diagramsfor the location of com-
plete heated seat system wiring diagrams.
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE AIRBAG SYSTEM. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
(1) If the problem being diagnosed involves inoper-
ative heated seat switch back lighting and the cluster
illumination lamps operate, go to Step 2. If the prob-
lem being diagnosed involves inoperative heated seat
switch back lighting and the cluster illumination
lamps are also inoperative, refer toInstrument
Clusterin the index of this service manual for the
proper cluster illumination lamps diagnosis and test-
ing procedures. If the problem being diagnosed
involves inoperative heated seat switch indicator
lamps and the heated seat elements do not heat,
refer to Step 4. If the problem being diagnosed
Fig. 17 Heated Seat Switches
1 - Driver Switch
2 - Passenger Switch
3 - Indicator Lamps
4 - Heated Seat Switch Bezel
BR/BEHEATED SEAT SYSTEM 8G - 17
PASSENGER SEAT HEATER SWITCH (Continued)

IGNITION COIL RESISTANCEÐ8.0L V-10
ENGINE
Primary Resistance: 0.53-0.65 Ohms. Test across the
primary connector. Refer to text for test procedures.
Secondary Resistance: 10.9-14.7K Ohms. Test
across the individual coil towers. Refer to text for test
procedures.
IGNITION TIMING
Ignition timing is not adjustable on any engine.
AUTOMATIC SHUT DOWN
RELAY
DESCRIPTION - PCM OUTPUT
The 5±pin, 12±volt, Automatic Shutdown (ASD)
relay is located in the Power Distribution Center
(PDC). Refer to label on PDC cover for relay location.
OPERATION
OPERATION - PCM OUTPUT
The ASD relay supplies battery voltage (12+ volts)
to the fuel injectors and ignition coil(s). With certain
emissions packages it also supplies 12±volts to the
oxygen sensor heating elements.
The ground circuit for the coil within the ASD
relay is controlled by the Powertrain Control Module
(PCM). The PCM operates the ASD relay by switch-
ing its ground circuit on and off.
The ASD relay will be shut±down, meaning the
12±volt power supply to the ASD relay will be de-ac-
tivated by the PCM if:
²the ignition key is left in the ON position. This
is if the engine has not been running for approxi-
mately 1.8 seconds.
²there is a crankshaft position sensor signal to
the PCM that is lower than pre-determined values.
OPERATION - ASD SENSE - PCM INPUT
A 12 volt signal at this input indicates to the PCM
that the ASD has been activated. The relay is used to
connect the oxygen sensor heater element, ignition
coil and fuel injectors to 12 volt + power supply.
This input is used only to sense that the ASD relay
is energized. If the Powertrain Control Module
(PCM) does not see 12 volts at this input when the
ASD should be activated, it will set a Diagnostic
Trouble Code (DTC).
DIAGNOSIS AND TESTING - ASD AND FUEL
PUMP RELAYS
The following description of operation and
tests apply only to the Automatic Shutdown
(ASD) and fuel pump relays. The terminals on the
bottom of each relay are numbered. Two different
types of relays may be used, (Fig. 1) or (Fig. 2).
Fig. 1 ASD and Fuel Pump Relay TerminalsÐType 1
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
Fig. 2 ASD and Fuel Pump Relay TerminalsÐType 2
TERMINAL LEGEND
NUMBER IDENTIFICATION
30 COMMON FEED
85 COIL GROUND
86 COIL BATTERY
87 NORMALLY OPEN
87A NORMALLY CLOSED
8I - 4 IGNITION CONTROLBR/BE
IGNITION CONTROL (Continued)

cause of oil entry into that particular combustion
chamber.
ELECTRODE GAP BRIDGING
Electrode gap bridging may be traced to loose
deposits in the combustion chamber. These deposits
accumulate on the spark plugs during continuous
stop-and-go driving. When the engine is suddenly
subjected to a high torque load, deposits partially liq-
uefy and bridge the gap between electrodes (Fig. 30).
This short circuits the electrodes. Spark plugs with
electrode gap bridging can be cleaned using standard
procedures.
SCAVENGER DEPOSITS
Fuel scavenger deposits may be either white or yel-
low (Fig. 31). They may appear to be harmful, but
this is a normal condition caused by chemical addi-
tives in certain fuels. These additives are designed to
change the chemical nature of deposits and decrease
spark plug misfire tendencies. Notice that accumula-
tion on the ground electrode and shell area may be
heavy, but the deposits are easily removed. Spark
plugs with scavenger deposits can be considered nor-
mal in condition and can be cleaned using standard
procedures.
CHIPPED ELECTRODE INSULATOR
A chipped electrode insulator usually results from
bending the center electrode while adjusting the
spark plug electrode gap. Under certain conditions,
severe detonation can also separate the insulator
from the center electrode (Fig. 32). Spark plugs with
this condition must be replaced.
PREIGNITION DAMAGE
Preignition damage is usually caused by excessive
combustion chamber temperature. The center elec-
trode dissolves first and the ground electrode dis-
solves somewhat latter (Fig. 33). Insulators appear
relatively deposit free. Determine if the spark plug
has the correct heat range rating for the engine.
Determine if ignition timing is over advanced or if
other operating conditions are causing engine over-
heating. (The heat range rating refers to the operat-
ing temperature of a particular type spark plug.
Spark plugs are designed to operate within specific
temperature ranges. This depends upon the thick-
ness and length of the center electrodes porcelain
insulator.)
Fig. 29 Oil or Ash Encrusted
Fig. 30 Electrode Gap Bridging
1 - GROUND ELECTRODE
2 - DEPOSITS
3 - CENTER ELECTRODE
Fig. 31 Scavenger Deposits
1 - GROUND ELECTRODE COVERED WITH WHITE OR
YELLOW DEPOSITS
2 - CENTER ELECTRODE
8I - 18 IGNITION CONTROLBR/BE
SPARK PLUG (Continued)

SPARK PLUG OVERHEATING
Overheating is indicated by a white or gray center
electrode insulator that also appears blistered (Fig.
34). The increase in electrode gap will be consider-
ably in excess of 0.001 inch per 2000 miles of opera-
tion. This suggests that a plug with a cooler heat
range rating should be used. Over advanced ignition
timing, detonation and cooling system malfunctions
can also cause spark plug overheating.
REMOVAL
On 5.9L engines, spark plug cable heat shields are
pressed into the cylinder head to surround each cable
boot and spark plug (Fig. 35).
(1) Always remove spark plug or ignition coil
cables by grasping at the cable boot (Fig. 37). Turn
the cable boot 1/2 turn and pull straight back in a
steady motion. Never pull directly on the cable.
Internal damage to cable will result.
Fig. 32 Chipped Electrode Insulator
1 - GROUND ELECTRODE
2 - CENTER ELECTRODE
3 - CHIPPED INSULATOR
Fig. 33 Preignition Damage
1 - GROUND ELECTRODE STARTING TO DISSOLVE
2 - CENTER ELECTRODE DISSOLVED
Fig. 34 Spark Plug Overheating
1 - BLISTERED WHITE OR GRAY COLORED INSULATOR
Fig. 35 Heat ShieldsÐ5.9L Engines
1 - AIR GAP
2 - SPARK PLUG BOOT HEAT SHIELD
BR/BEIGNITION CONTROL 8I - 19
SPARK PLUG (Continued)

POWER MIRRORS
TABLE OF CONTENTS
page page
POWER MIRRORS
DESCRIPTION.........................11
OPERATION...........................11
AUTOMATIC DAY / NIGHT MIRROR
DESCRIPTION.........................11
OPERATION...........................12
DIAGNOSIS AND TESTING - AUTOMATIC
DAY/NIGHT MIRROR...................12
REMOVAL.............................13
INSTALLATION.........................13
POWER MIRROR SWITCH
DESCRIPTION.........................13OPERATION...........................13
REMOVAL.............................13
INSTALLATION.........................14
SIDEVIEW MIRROR
DESCRIPTION.........................14
OPERATION...........................14
DIAGNOSIS AND TESTING - SIDEVIEW
MIRROR............................14
REMOVAL.............................15
POWER MIRRORS
DESCRIPTION
AUTOMATIC DAY / NIGHT MIRROR
The automatic day/night mirror system is able to
automatically change the reflectance of the inside
rear view mirror in order to reduce the glare of head-
lamps approaching the vehicle from the rear. The
automatic day/night rear view mirror receives bat-
tery current through a fuse in the junction block only
when the ignition switch is in the On position.
OUTSIDE REAR VIEW MIRROR
The heated mirror option includes an electric heat-
ing grid behind the mirror glass in each outside mir-
ror, which can clear the mirror glass of ice, snow, or
fog. The heating grid receives fused battery current
through the heated mirror relay in the heater and air
conditioner control only when the ignition switch is
in the On position, and the heated mirror system is
turned on. (Refer to 8 - ELECTRICAL/HEATED
MIRRORS - DESCRIPTION) for more information.
Refer to the owner's manual in the vehicle glove
box for more information on the features, use and
operation of the power mirror system.
OPERATION
AUTOMATIC DAY / NIGHT MIRROR
A switch located on the bottom of the automatic
day/night mirror housing allows the vehicle operator
to select whether the automatic dimming feature is
operational. When the automatic day/night mirror isturned on, the mirror switch is lighted by an integral
Light-Emitting Diode (LED). The mirror will auto-
matically disable its self-dimming feature whenever
the vehicle is being driven in reverse.
Refer to the owner's manual in the vehicle glove
box for more information on the features, use and
operation of the automatic day/night mirror system.
OUTSIDE REAR VIEW MIRROR
The heated mirror option includes an electric heat-
ing grid behind the mirror glass in each outside mir-
ror, which can clear the mirror glass of ice, snow, or
fog. The heating grid receives fused battery current
through the heated mirror relay in the heater and air
conditioner control only when the ignition switch is
in the On position, and the heated mirror system is
turned on. (Refer to 8 - ELECTRICAL/HEATED
MIRRORS - OPERATION) for more information.
Refer to the owner's manual in the vehicle glove
box for more information on the features, use and
operation of the power mirror system.
AUTOMATIC DAY / NIGHT
MIRROR
DESCRIPTION
The automatic day/night mirror uses a thin layer
of electrochromic material between two pieces of con-
ductive glass to make up the face of the mirror.
When the mirror switch is in the On position, two
photocell sensors are used by the mirror circuitry to
monitor external light levels and adjust the reflec-
tance of the mirror.
BR/BEPOWER MIRRORS 8N - 11

INSTALLATION
(1) Insert the power mirror switch to the back of
the door trim panel.
(2) Connect the power mirror switch to the har-
ness connector.
(3) Install the trim panel to the inside of the
driver side door. (Refer to 23 - BODY/DOOR -
FRONT/TRIM PANEL - INSTALLATION).
(4) Install the nut that secures the power mirror
switch to the driver side front door.
(5) Push the control knob on to the power mirror
switch.
(6) Connect the battery negative cable.
SIDEVIEW MIRROR
DESCRIPTION
Each power mirror head contains two electric
motors, two drive mechanisms, and the mirror glass.
One motor and drive controls mirror up-and-down
movement, and the other controls right-and-left
movement.
OPERATION
The power mirrors in vehicles equipped with the
available heated mirror system option also include an
electric heating grid located behind the mirror glass.
This heating grid is energized by the heated mirror
relay in the heater and air conditioner control only
when the ignition switch is in the On position, and
the heated mirror system is turned on. (Refer to 8 -
ELECTRICAL/HEATED MIRRORS - DESCRIP-
TION) for more information.
The power mirror assembly cannot be repaired. If
any component of the power mirror unit is faulty or
damaged, the entire assembly must be replaced.
DIAGNOSIS AND TESTING - SIDEVIEW
MIRROR
For circuit descriptions and diagrams, refer to the
appropriate wiring information. The wiring informa-
tion includes wiring diagrams, proper wire and con-
nector repair procedures, details of wire harness
routing and retention, connector pin-out information
and location views for the various wire harness con-
nectors, splices and grounds.
(1) Check the fuses in the Power Distribution Cen-
ter (PDC) and the junction block. If OK, go to Step 2.
If not OK, repair the shorted circuit or component as
required and replace the faulty fuse(s).(2) Check for battery voltage at the fuse in the
junction block. If OK, go to Step 3. If not OK, repair
the open circuit to the PDC as required.
(3) Disconnect and isolate the battery negative
cable. Remove the driver side door trim panel and
unplug the wire harness connector from the power
mirror switch. Connect the battery negative cable.
Check for battery voltage at the fused B(+) circuit
cavity in the door wire harness half of the power mir-
ror switch wire harness connector. If OK, go to Step
4. If not OK, repair the open circuit to the junction
block as required.
(4) Disconnect and isolate the battery negative
cable. Check for continuity between the ground cir-
cuit cavity in the door wire harness half of the power
mirror switch wire harness connector and a good
ground. There should be continuity. If OK, go to Step
5. If not OK, repair the circuit to ground as required.
(5) Check the power mirror switch continuity as
shown in (Fig. 4). If OK, go to Step 6. If not OK,
replace the faulty switch.
Fig. 4 Power Mirror Switch Continuity
MIRROR SELECTOR KNOB IN9L9POSITION
MOVE LEVER CONTINUITY BETWEEN
UP Pins 3 and 8, 1 and 7, 4 and 7
RIGHT Pins 3 and 7, 2 and 8, 5 and 8
DOWN Pins 3 and 7, 1 and 8, 4 and 8
LEFT Pins 3 and 8, 2 and 7, 5 and 7
MIRROR SELECTOR KNOB IN(R(POSITION
MOVE LEVER CONTINUITY BETWEEN
UP Pins 6 and 8, 1 and 7, 4 and 7
RIGHT Pins 6 and 7, 2 and 8, 4 and 8
DOWN Pins 6 and 7, 1 and 8, 4 and 8
LEFT Pins 6 and 8, 2 and 7, 5 and 7
8N - 14 POWER MIRRORSBR/BE
POWER MIRROR SWITCH (Continued)

PASSENGER AIRBAG
DESCRIPTION
The rearward facing surface of the passenger air-
bag door above the glove box is the most visible part
of the passenger airbag. The airbag used in this
model is a Next Generation-type that complies with
revised federal airbag standards to deploy with less
force than those used in some prior models. The pas-
senger airbag is located in the instrument panel in
front of the front seat passenger seating position,
where it is secured to the instrument panel. Con-
cealed beneath the passenger airbag door are the
folded airbag cushion, the airbag retainer or housing,
and the airbag inflator. The airbag inflator is a
hybrid-type unit that is secured to and sealed within
the stamped steel airbag housing along with the
folded airbag cushion. The airbag housing stamping
also includes the two mounting brackets, one front
and one rear. The front bracket is secured beneath
the instrument panel top cover with screws to the
instrument panel structural support. The rear
bracket is secured with screws to the upper glove box
opening reinforcement. A yellow connector on the end
of a short, two-wire pigtail harness connects the pas-
senger airbag inflator to the vehicle electrical system.
The molded plastic passenger airbag door has pre-
determined breakout lines concealed beneath its dec-
orative cover. The lower edge of the passenger airbag
door is secured to the airbag housing, and includes
the two passenger side panel outlets. The sides and
upper edges are secured to the instrument panel top
cover with five molded tabs that are each fit with a
small metal retainer. The five retainers are snapped
into five slotted receptacles located around the sides
and top of the airbag door opening in the instrument
panel top cover. Following a passenger airbag deploy-
ment, the passenger airbag and airbag door unit
must be replaced. The passenger airbag cannot be
repaired, and must be replaced if faulty or in any
way damaged. The passenger airbag door is serviced
only as a unit with the passenger airbag, and
includes the two passenger side heating and air con-
ditioning panel outlet housings and barrels.
OPERATION
The passenger airbag is deployed by an electrical
signal generated by the Airbag Control Module
(ACM) through the passenger airbag line 1 and line 2
(or squib) circuits. The hybrid-type inflator assembly
includes a small canister of highly compressed argon
gas. When the ACM sends the proper electrical signal
to the airbag inflator, the electrical energy generates
enough heat to ignite chemical pellets within the
inflator. Once ignited, these chemical pellets burn
rapidly and produce the pressure necessary to rup-ture a containment disk in the argon gas canister.
The inflator and argon gas canister are sealed to the
airbag cushion so that all of the released argon gas is
directed into the airbag cushion, causing the cushion
to inflate. As the cushion inflates, the passenger air-
bag door will split at the breakout lines and the door
will pivot out of the way. Following an airbag deploy-
ment, the airbag cushion quickly deflates by venting
the argon gas through the porous fabric material
used on each end panel of the airbag cushion.
Some of the chemicals used to create the pressure
to burst the argon gas containment disk are consid-
ered hazardous in their solid state, before they are
burned, but they are securely sealed within the air-
bag inflator. However, the gas that is produced when
the chemicals are burned is harmless. A small
amount of residue from the burned chemicals may
cause some temporary discomfort if it contacts the
skin, eyes, or breathing passages. If skin or eye irri-
tation is noticed, rinse the affected area with plenty
of cool, clean water. If breathing passages are irri-
tated, move to another area where there is plenty of
clean, fresh air to breath. If the irritation is not alle-
viated by these actions, contact a physician immedi-
ately.
REMOVAL
WARNING: DISABLE THE AIRBAG SYSTEM
BEFORE ATTEMPTING ANY STEERING WHEEL,
STEERING COLUMN, OR INSTRUMENT PANEL
COMPONENT DIAGNOSIS OR SERVICE. DISCON-
NECT AND ISOLATE THE BATTERY NEGATIVE
(GROUND) CABLE, THEN WAIT TWO MINUTES FOR
THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE
BEFORE PERFORMING FURTHER DIAGNOSIS OR
SERVICE. THIS IS THE ONLY SURE WAY TO DIS-
ABLE THE AIRBAG SYSTEM. FAILURE TO TAKE
THE PROPER PRECAUTIONS COULD RESULT IN
ACCIDENTAL AIRBAG DEPLOYMENT AND POSSI-
BLE PERSONAL INJURY.
WARNING: WHEN REMOVING A DEPLOYED AIR-
BAG, RUBBER GLOVES, EYE PROTECTION, AND A
LONG-SLEEVED SHIRT SHOULD BE WORN. THERE
MAY BE DEPOSITS ON THE AIRBAG UNIT AND
OTHER INTERIOR SURFACES. IN LARGE DOSES,
THESE DEPOSITS MAY CAUSE IRRITATION TO THE
SKIN AND EYES.
(1) Disconnect and isolate the battery negative
cable. If either of the airbags has not been deployed,
wait two minutes for the system capacitor to dis-
charge before further service.
BR/BERESTRAINTS 8O - 21

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 ECM.
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
ECM when the RES/ACCEL is released. The ECM
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.
DIAGNOSIS AND TESTING
DIAGNOSIS AND TESTING - VACUUM SUPPLY
TEST
Gas Powered Engines
On gasoline 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.
(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 reservoirand 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.
Diesel Engines With Automatic Trans.
On diesel powered engines equipped with an auto-
matic transmission: an engine driven vacuum pump,
a one-way check valve and vacuum lines are used to
supply vacuum to the speed control servo. A vacuum
reservoir is not used.
(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. For
vacuum testing and vacuum specifications, refer to
Vacuum Pump OutputÐDiesel Engine in 9, Engines.
(3) If vacuum pump output is OK, determine other
source of leak. Check all vacuum lines to: speed con-
trol servo, engine vacuum pump and heating/air con-
ditioning system for leaks.
(4) 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 speed control servo
and engine vacuum pump. 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.
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.
BR/BESPEED CONTROL 8P - 3
SPEED CONTROL (Continued)

INSTALLATION
(1) Install electrical connector to switch.
(2) Install switch and mounting screws.
(3) Tighten screws to 3 N´m (26 in. lbs. +/± 2 in.
lbs.) torque.
(4) Install airbag module. Refer to 8, Restraint
Systems for procedures.
(5) Connect negative battery cable(s).
VACUUM RESERVOIR
DESCRIPTION
Gasoline Powered Engines :A vacuum reservoir
is used to supply the vacuum needed to maintain
proper speed control operation 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 res-
ervoir. On certain vehicle applications, this reservoir
is shared with the heating/air-conditioning system.
The vacuum reservoir cannot be repaired and must
be replaced if faulty.
Diesel Powered Engines With Auto. Trans. :A
vacuum reservoir is not used if equipped with a die-
sel powered engine. Instead, an engine driven pump
(vacuum pump) is used to supply vacuum for speed
control operation. This vacuum pump is used with
the diesel engine only if it is equipped with an auto-
matic transmission. Refer to Vacuum Pump in 9,
Engines for information.
REMOVAL
The vacuum reservoir is located under the plastic
cowel plenum cover at lower base of windshield. The
vacuum reservoir is not used if equipped with a die-
sel engine.
(1) Disconnect and isolate battery negative cable.
(2) Remove both windshield wiper arm/blade
assemblies. Refer to 8, Wiper and Washer Systems.
(3) Remove rubber weather-strip at front edge of
cowel grill (Fig. 21).
(4) Release cowel grill plastic anchor screws (Fig.
22).
Fig. 20 Speed Control Switches
1 - MOUNTING SCREWS (2)
2 - SPEED CONTROL SWITCHES (2)
Fig. 21 Cowel Grille Panel Weather-strip
1 - COWL GRILLE
2 - WEATHERSTRIP
Fig. 22 Plastic Anchor Screws Remove/Install
1 - PLASTIC SCREW ANCHOR
2 - COWL GRILLE
8P - 14 SPEED CONTROLBR/BE
SWITCH (Continued)