1998 DODGE RAM 1500 Coil

(4) Install ignition coil(s). Refer to Ignition Coil
Removal/Installation.
5.7L V-8
(1) Special care should be taken when installing
spark plugs into the cylinder head spark plug wells.
Be sure the plugs do not drop into the plug wells as
electrodes can be damaged.
(2) Start the spark plug into cylinder head by
hand to avoid cross threading aluminum threads. To
aid in installation, attach a piece of rubber hose, or
an old spark plug boot to spark plug.
(3) The 5.7L V-8 is equipped with torque critical
design spark plugs. Do not exceed 15 ft. lbs. torque.
Tighten spark plugs. Refer to torque specifications.
(4) Before installing spark plug cables to either the
spark plugs or coils, apply dielectric grease to inside
of boots.
(5) To prevent ignition crossfire, spark plug cables
MUSTbe placed in cable tray (routing loom) into
their original position. Refer to Spark Plug Cable
Removal for a graphic.
(6) Install ignition coil(s) to necessary spark plugs.
Refer to Ignition Coil Installation.
(7) Install spark plug cables to remaining spark
plugs. Remember to apply dielectric grease to inside
of boots.
IGNITION COIL CAPACITOR
DESCRIPTION
One coil capacitor is used. It is located in the right-
rear section of the engine compartment.
OPERATION
The coil capacitor(s) help dampen the amount of
conducted electrical noise to the camshaft position
sensor, crankshaft position sensor, and throttle posi-
tion sensor. This noise is generated on the 12V sup-
ply wire to the ignition coils and fuel injectors.
REMOVAL
The coil capacitor is located in the right-rear sec-
tion of the engine compartment. It is attached with a
mounting stud and nut.
(1) Disconnect electrical connector at capacitor
(Fig. 31).
(2) Remove mounting nut and remove ground
strap.
(3) Remove capacitor.
INSTALLATION
(1) Position capacitor to mounting stud.
(2) Position ground strap to mounting stud.
(3) Tighten nut to 7 N´m (60 in. lbs.) torque.
(4) Connect electrical connector to coil capacitor.
SPARK PLUG CABLE
DESCRIPTION
Spark plug cables are sometimes referred to as sec-
ondary ignition wires, or secondary ignition cables.
Plug cables are used only on the 5.7L V-8 engine.
OPERATION
The spark plug cables transfer electrical current
from the ignition coil(s) and/or distributor, to individ-
ual spark plugs at each cylinder. The resistive spark
plug cables are of nonmetallic construction. The
cables provide suppression of radio frequency emis-
sions from the ignition system.
Plug cables are used only on the 5.7L V-8 engine.
Fig. 31 CAPACITOR LOCATION
1 - COIL CAPACITOR
2 - MOUNTING STUD
3 - GROUND STRAP
4 - MOUNTING NUT
5 - ELEC. CONNECT.
DRIGNITION CONTROL 8I - 21
SPARK PLUG (Continued)

REMOVAL
5.7L V-8
Spark plug cables on the 5.7L engine are paired on
cylinders 1/6, 2/3, 4/7 and 5/8. Before removing or
disconnecting any spark plug cables, note their orig-
inal position (Fig. 32). Remove cables one-at-a-time.
To prevent ignition crossfire, spark plug cables
MUSTbe placed in cable tray (routing loom) into
their original position. The cable retention clips (Fig.
32) must also be securly locked.
Before installing spark plug cables to either the
spark plugs or coils, apply dielectric grease to inside
of boots.
If cable tray removal is necessary, release the 4
tray-to-manifold retention clips (Fig. 32).
INSTALLATION
Install cables into the proper engine cylinder firing
order sequence. Refer to Specifications.
When replacing the spark plug and coil cables,
route the cables correctly and secure them in the
proper retainers. Failure to route the cables properly
may cause the radio to reproduce ignition noise. It
could also cause cross-ignition of the plugs, or, may
short-circuit the cables to ground.
When installing new cables, make sure a positive
connection is made. A snap should be felt when a
good connection is made.
5.7L V-8
Refer to Spark Plug Cable Removal for
information.
Fig. 32 5.7L SPARK PLUG CABLE ROUTING
1 - #8 COIL-TO- #5 SPARK PLUG (MARKED 5/8) 7 - CABLE TRAY
2 - #5 COIL-TO- #8 SPARK PLUG (MARKED 5/8) 8 - CLIPS (SPARK PLUG CABLE-TO-TRAY- RETENTION)
3 - #7 COIL-TO- #4 SPARK PLUG (MARKED 4/7) 9 - #2 COIL-TO- #3 SPARK PLUG (MARKED 2/3)
4 - #3 COIL-TO- #2 SPARK PLUG (MARKED 2/3) 10 - #6 COIL-TO- #1 SPARK PLUG (MARKED 1/6)
5 - #1 COIL-TO- #6 SPARK PLUG (MARKED 1/6) 11 - #4 COIL-TO- #7 SPARK PLUG (MARKED 4/7)
6 - CLIPS (TRAY-TO-MANIFOLD RETENTION)
8I - 22 IGNITION CONTROLDR
SPARK PLUG CABLE (Continued)

sage-controlled functions of the cluster by lighting
the appropriate indicators, positioning the gauge nee-
dles at several predetermined calibration points
across the gauge faces, and illuminating all segments
of the odometer/trip odometer and gear selector indi-
cator Vacuum-Fluorescent Display (VFD) units.
(Refer to 8 - ELECTRICAL/INSTRUMENT CLUS-
TER - DIAGNOSIS AND TESTING). See the owner's
manual in the vehicle glove box for more information
on the features, use and operation of the EMIC.
GAUGES
All gauges receive battery current through the
EMIC circuitry only when the ignition switch is in
the On or Start positions. With the ignition switch in
the Off position battery current is not supplied to
any gauges, and the EMIC circuitry is programmed
to move all of the gauge needles back to the low end
of their respective scales. Therefore, the gauges do
not accurately indicate any vehicle condition unless
the ignition switch is in the On or Start positions.
All of the EMIC gauges are air core magnetic
units. Two fixed electromagnetic coils are located
within each gauge. These coils are wrapped at right
angles to each other around a movable permanent
magnet. The movable magnet is suspended within
the coils on one end of a pivot shaft, while the gauge
needle is attached to the other end of the shaft. One
of the coils has a fixed current flowing through it to
maintain a constant magnetic field strength. Current
flow through the second coil changes, which causes
changes in its magnetic field strength. The current
flowing through the second coil is changed by the
EMIC circuitry in response to messages received over
the PCI data bus. The gauge needle moves as the
movable permanent magnet aligns itself to the
changing magnetic fields created around it by the
electromagnets.
The gauges are diagnosed using the EMIC self-di-
agnostic actuator test. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). Proper testing of the PCI data bus and
the electronic data bus message inputs to the EMIC
that control each gauge require the use of a DRBIIIt
scan tool. Refer to the appropriate diagnostic infor-
mation. Specific operation details for each gauge may
be found elsewhere in this service information.
VACUUM-FLUORESCENT DISPLAYS
The Vacuum-Fluorescent Display (VFD) units are
soldered to the EMIC electronic circuit board. With
the ignition switch in the Off or Accessory positions,
the odometer display is activated when the driver
door is opened (Rental Car mode) and is deactivated
when the driver door is closed. Otherwise, both dis-
play units are active when the ignition switch is inthe On or Start positions, and inactive when the igni-
tion switch is in the Off or Accessory positions.
The illumination intensity of the VFD units is con-
trolled by the EMIC circuitry based upon an input
from the headlamp switch and a dimming level input
received from the headlamp dimmer switch. The
EMIC synchronizes the illumination intensity of
other VFD units with that of the units in the EMIC
by sending electronic dimming level messages to
other electronic modules in the vehicle over the PCI
data bus.
The EMIC VFD units have several display capabil-
ities including odometer, trip odometer, engine hours,
gear selector indication (PRNDL) for models with an
automatic transmission, several warning or reminder
indications, and various diagnostic information when
certain fault conditions exist. An odometer/trip odom-
eter switch on the EMIC circuit board is used to con-
trol some of the display modes. This switch is
actuated manually by depressing the odometer/trip
odometer switch button that extends through the
lower edge of the cluster lens, just left of the tachom-
eter. Actuating this switch momentarily with the
ignition switch in the On position will toggle the
VFD between the odometer and trip odometer modes.
Depressing the switch button for about two seconds
while the VFD is in the trip odometer mode will
reset the trip odometer value to zero. While in the
odometer mode with the ignition switch in the On
position and the engine not running, depressing this
switch for about six seconds will display the engine
hours information. Holding this switch depressed
while turning the ignition switch from the Off posi-
tion to the On position will initiate the EMIC self-di-
agnostic actuator test. Refer to the appropriate
diagnostic information for additional details on this
VFD function. The EMIC microprocessor remembers
which display mode is active when the ignition
switch is turned to the Off position, and returns the
VFD display to that mode when the ignition switch is
turned On again.
The VFD units are diagnosed using the EMIC self-
diagnostic actuator test. (Refer to 8 - ELECTRICAL/
INSTRUMENT CLUSTER - DIAGNOSIS AND
TESTING). Proper testing of the PCI data bus and
the electronic data bus message inputs to the EMIC
that control some of the VFD functions requires the
use of a DRBIIItscan tool. Refer to the appropriate
diagnostic information. Specific operation details for
the odometer, the trip odometer, the gear selector
indicator and the various warning and reminder indi-
cator functions of the VFD may be found elsewhere
in this service information.
8J - 8 INSTRUMENT CLUSTERDR
INSTRUMENT CLUSTER (Continued)

INSTALLATION
(1) Quarter twist the bulb socket clockwise into
the lamp housing.
(2) Position the lamp assembly onto the roof and
install retaining screws. (Fig. 7)
FOG LAMP
REMOVAL
NOTE: The fog lamps are serviced from the rear-
ward side of the front bumper.
(1) Disconnect and isolate the battery negative
cable.
(2) Disengage fog lamp harness connector.
(3) Remove the bolts attaching the fog lamp to the
bumper (Fig. 8).
(4) Separate fog lamp from bumper.
INSTALLATION
(1) Position fog lamp in bumper.
(2) Install the bolts attaching the fog lamp to the
bumper.
(3) Connect fog lamp harness connector.
(4) Connect the battery negative cable.(5) Check for proper operation and beam align-
ment.
FOG LAMP RELAY
DESCRIPTION
The front fog lamp relay is located in the Power
Distribution Center (PDC) in the engine compart-
Fig. 7 Clearance Lamp
1 - NUT
2 - CAB ROOF
3 - BULB SOCKET
4 - CLEARANCE LAMP
5 - SCREW
6 - BULB
Fig. 8 Fog Lamp
1 - SCREW
2 - FOG LAMP UNIT
3 - CONNECTOR
Fig. 9 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
8L - 12 LAMPS/LIGHTING - EXTERIORDR
CAB CLEARANCE LAMP (Continued)

ment of the vehicle. The front fog lamp relay is a
conventional International Standards Organization
(ISO) micro relay (Fig. 9). Relays conforming to the
ISO specifications have common physical dimensions,
current capacities, terminal patterns, and terminal
functions. The relay is contained within a small, rect-
angular, molded plastic housing and is connected to
all of the required inputs and outputs by five integral
male spade-type terminals that extend from the bot-
tom of the relay base.
The front fog lamp relay cannot be adjusted or
repaired and, if faulty or damaged, the unit must be
replaced.
OPERATION
The front fog lamp relay is an electromechanical
switch that uses a low current input from the Front
Control Module (FCM) to control a high current out-
put to the front fog 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 windings. 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 is connected in parallel with the relay coil in
the relay, and helps to dissipate voltage spikes and
electromagnetic interference that can be generated as
the electromagnetic field of the relay coil collapses.
The front fog lamp relay terminals are connected
to the vehicle electrical system through a connector
receptacle in the Power Distribution Center (PDC).
The inputs and outputs of the front fog lamp relay
include:
²Common Feed Terminal- The common feed
terminal (30) receives battery voltage at all times
from a fuse in the PDC through a fused B(+) circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the Front
Control Module (FCM) through a front fog lamp relay
control circuit. The FCM controls front fog lamp oper-
ation by controlling a ground path through this cir-
cuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery voltage at all times from
a fuse in the PDC through a fused B(+) circuit.
²Normally Open Terminal- The normally open
terminal (87) is connected to the front fog lamps
through a front fog lamp relay output circuit and
provides battery voltage to the front fog lamps when-
ever the relay is energized.²Normally Closed Terminal- The normally
closed terminal (87A) is not connected in this appli-
cation.
The front fog lamp relay can be diagnosed using
conventional diagnostic tools and methods. Refer to
the appropriate wiring information for diagnosis and
testing of the front fog lamp micro-relay and for com-
plete wiring diagrams.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER 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 AND POSSIBLE
PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the cover for the Power Distribution
Center (PDC).
(3) Remove the front fog lamp relay by grasping it
firmly and pulling it straight out from the receptacle
in the PDC.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER 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 AND POSSIBLE
PERSONAL INJURY.
DRLAMPS/LIGHTING - EXTERIOR 8L - 13
FOG LAMP RELAY (Continued)

PARK LAMP RELAY
DESCRIPTION
The park lamp relay is located in the Power Dis-
tribution Center (PDC) of the vehicle. The park lamp
relay is a conventional International Standards
Organization (ISO) micro relay (Fig. 17). Relays con-
forming to the ISO specifications have common phys-
ical dimensions, current capacities, terminal
patterns, and terminal functions.
The park lamp relay cannot be adjusted or
repaired and, if faulty or damaged, the unit must be
replaced.
OPERATION
The park lamp relay is an electromechanical
switch that uses a low current input from the Front
Control Module (FCM) to control a high current out-
put to the park 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 windings. 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 is connected in parallel with the relay coil in
the relay, and helps to dissipate voltage spikes and
electromagnetic interference that can be generated as
the electromagnetic field of the relay coil collapses.The park lamp relay terminals are connected to
the vehicle electrical system through a connector in
the Junction Block (JB). The inputs and outputs of
the headlamp low beam relay include:
²Common Feed Terminal- The common feed
terminal (30) is connected to the park lamps through
the park lamp relay output circuit and provides
ground to the park lamps when the relay is de-ener-
gized, and battery current to the park lamps when-
ever the relay is energized.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the Front
Control Module (FCM) through a park lamp relay
control circuit. The FCM controls park lamp opera-
tion by controlling a ground path through this cir-
cuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the PDC through a fused B(+) circuit.
²Normally Open Terminal- The normally open
terminal (87) receives battery current at all times
from a fuse in the Power Distribution Center (PDC)
through a fused B(+) circuit.
²Normally Closed Terminal- The normally
closed terminal (87A) is connected to ground at all
times.
The park lamp relay can be diagnosed using con-
ventional diagnostic tools and methods.
DIAGNOSIS AND TESTING - PARK LAMP
RELAY
The park lamp relay (Fig. 18) is located in the
Power Distribution Center (PDC). Refer to the appro-
priate wiring information.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER 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 AND POSSIBLE
PERSONAL INJURY.
(1) Remove the park lamp relay from the PDC.
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
Fig. 17 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
8L - 20 LAMPS/LIGHTING - EXTERIORDR

no continuity between terminals 87 and 30. If OK, go
to Step 3. If not OK, replace the faulty relay.
(3) Resistance between terminals 85 and 86 (elec-
tromagnet) should be 75   8 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
(4) Connect a battery to terminals 85 and 86.
There should now be continuity between terminals
30 and 87, and no continuity between terminals 87A
and 30. If OK, reinstall the relay and use a DRBIIIt
scan tool to perform further testing. Refer to the
appropriate diagnostic information.
REMOVAL
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER 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 AND POSSIBLE
PERSONAL INJURY.
(1) Disconnect and isolate the battery negative
cable.(2) Remove the Power Distribution Center (PDC)
cover.
(3) Remove the park lamp relay by grasping it
firmly and pulling it straight out from the receptacle
in the PDC.
INSTALLATION
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, DISABLE THE SUPPLEMENTAL RESTRAINT
SYSTEM BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, DRIVER AIRBAG,
PASSENGER AIRBAG, SEAT BELT TENSIONER,
FRONT IMPACT SENSORS, SIDE CURTAIN AIRBAG,
OR INSTRUMENT PANEL COMPONENT DIAGNOSIS
OR SERVICE. DISCONNECT AND ISOLATE THE
BATTERY NEGATIVE (GROUND) CABLE, THEN
WAIT TWO MINUTES FOR THE SYSTEM CAPACI-
TOR TO DISCHARGE BEFORE PERFORMING FUR-
THER 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 AND POSSIBLE
PERSONAL INJURY.
(1) Position the park lamp relay to the proper
receptacle in the Power Distribution Center (PDC).
(2) Align the park lamp relay terminals with the
terminal cavities in the PDC.
(3) Press firmly and evenly on the top of the park
lamp relay until the terminals are fully seated in the
PDC.
(4) Install the PDC cover.
(5) Reconnect the battery negative cable.
PARK/TURN SIGNAL LAMP
REMOVAL
(1) Disconnect and isolate the negative battery
cable.
(2) Remove the headlamp unit.(Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/HEAD-
LAMP UNIT - REMOVAL).
(3) Remove the bulb socket from the headlamp
unit.
(4) Release the front park/turn signal bulb locking
tabs and remove the bulb from the socket (Fig. 19).
INSTALLATION
(1) Install the front park/turn signal bulb into the
bulb socket.
(2) Install the bulb socket into the headlamp unit.
(3) Install the headlamp unit (Refer to 8 - ELEC-
TRICAL/LAMPS/LIGHTING - EXTERIOR/HEAD-
LAMP UNIT - INSTALLATION).
Fig. 18 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
DRLAMPS/LIGHTING - EXTERIOR 8L - 21
PARK LAMP RELAY (Continued)

OPERATION
The seat belt tension reducer is controlled by a
ground signal received from the seat belt switch on
the seat belt switch sense circuit and a battery cur-
rent signal received from the ignition switch on the
fused ignition switch output (run-accessory) circuit.
When the seat belt switch is closed (the driver side
front seat belt is fastened) and the ignition switch is
in the On or Accessory positions, the seat belt tension
reducer solenoid is energized. When the solenoid is
energized, it actuates a mechanism within the driver
side front outboard seat belt retractor to reduce the
normal recoil spring tension exerted by the retractor
spool, which is designed to reel in the seat belt web-
bing onto the spool. When the driver side seat belt is
unbuckled or if the ignition switch is turned to any
position except On or Accessory, the tension reducer
solenoid is de-energized and the normal recoil spring
tension of the retractor is restored.
The action of the seat belt tension reducer results
in improved seat belt comfort for the driver. Reducing
the seat belt retractor recoil spring tension is desir-
able on standard cab models of this vehicle and not
on the quad cab model due to the different mounting
position required for the seat belt turning loop on the
B-pillar relative to the driver's seat position on the
standard cab model. The seat belt tension reducer
may be diagnosed using conventional diagnostic tools
and methods.
DIAGNOSIS AND TESTING - SEAT BELT
TENSION REDUCER
Refer to the appropriate wiring 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.
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. Disconnect the body wire harness connector for
the seat belt tension reducer from the tension
reducer connector receptacle on the driver side front
outboard seat belt and retractor unit. Using an ohm-
meter, measure the resistance between the seat belt
switch sense circuit terminal pin and the fused igni-
tion switch output (run-accessory) circuit terminal
pin in the tension reducer connector receptacle on
the retractor. Resistance through the tension reducer
solenoid coil should be 53 ohms at 20É C (68É F). If
OK, go to Step 2. If not OK, replace the faulty driver
side front outboard seat belt and retractor unit.
(2) Check for continuity between the seat belt
switch sense circuit cavity of the body wire harness
connector for the seat belt tension reducer and a good
ground. There should be continuity with the driver
side front seat belt buckled, and no continuity with
the driver side front seat belt unbuckled. If OK, go to
Step 3. If not OK, repair the shorted or open seat
belt switch sense circuit between the tension reducer
and the seat belt switch as required.
(3) Reconnect the battery negative cable. Check for
battery current at the fused ignition switch output
(run-accessory) circuit of the body wire harness con-
nector for the seat belt tension reducer. There should
be battery current with the ignition switch in the On
or Accessory positions, and no battery current with
the ignition switch in any other position. If not OK,
repair the shorted or open fused ignition switch out-
put (run-accessory) circuit between the tension
reducer and the ignition switch as required.
8O - 54 RESTRAINTSDR
SEAT BELT TENSION REDUCER (Continued)