headlamp DODGE RAM 2001 Service Owner's Manual

MARKER LAMP
REMOVAL..............................22
INSTALLATION...........................23
MULTI-FUNCTION SWITCH
DESCRIPTION...........................23
OPERATION.............................24
DIAGNOSIS AND TESTING.................25
MULTI-FUNCTION SWITCH...............25
REMOVAL..............................27
INSTALLATION...........................28
OUTBOARD IDENTIFICATION LAMP
REMOVAL..............................28
INSTALLATION...........................29
PARK/TURN SIGNAL LAMP
REMOVAL..............................29
INSTALLATION...........................29
PARK/TURN SIGNAL LAMP UNIT
REMOVAL..............................29INSTALLATION...........................29
TAIL LAMP
DESCRIPTION...........................29
OPERATION.............................29
REMOVAL..............................29
INSTALLATION...........................30
TAIL LAMP UNIT
REMOVAL..............................30
INSTALLATION...........................30
TURN SIGNAL CANCEL CAM
DESCRIPTION...........................30
OPERATION.............................31
UNDERHOOD LAMP
REMOVAL..............................31
INSTALLATION...........................32
UNDERHOOD LAMP UNIT
REMOVAL..............................32
INSTALLATION...........................32
LAMPS/LIGHTING - EXTERIOR
DESCRIPTION - TURN SIGNAL & HAZARD
WARNING SYSTEM
A turn signal and hazard warning system is stan-
dard factory-installed safety equipment on this
model. The turn signal and hazard warning system
includes the following major components, which are
described in further detail elsewhere in this service
information:
²Combination Flasher- The electronic combi-
nation flasher is installed in the Junction Block (JB),
which is located behind the fuse access panel on the
left outboard end of the instrument panel.
²Hazard Warning Switch- The hazard warning
switch is integral to the multi-function switch on the
left side of the steering column. The hazard warning
switch button protrudes from a dedicated opening in
the shroud on the top of the steering column, just
below the steering wheel.
²Turn Signal Cancel Cam- The turn signal
cancel cam is integral to the clockspring, which is
located beneath the steering column shrouds at the
top of the steering column, just below the steering
wheel.
²Turn Signal Indicators- The two turn signal
indicators, one right and one left, are integral to the
ElectroMechanical Instrument Cluster (EMIC)
located in the instrument panel.
²Turn Signal Lamps- The front turn signal
lamps are integral to the lower front outboard ends
of the headlamp modules, located just outboard of the
two sides of the radiator grille opening. The rear
turn signal lamps are integral to the taillamp mod-
ules located on either side of the vehicle. For pickup
models the taillamp modules are secured to the rear
of the quarter panels at each side of the tailgate
opening. For cab and chassis models the taillampmodules are secured by a stamped steel bracket on
the outboard side of each frame rail near the rear of
the vehicle.
²Turn Signal Switch- The turn signal switch is
integral to the multi-function switch on the left side
of the steering column. The multi-function switch
control stalk that actuates the turn signal switch
protrudes from a dedicated opening in the steering
column shrouds on the left side of the column, just
below the steering wheel.
Hard wired circuitry connects the turn signal and
hazard warning system components to each other
through the electrical system of the vehicle. These
hard wired circuits are integral to several wire har-
nesses, which are routed throughout the vehicle and
retained by many different methods. These circuits
may be connected to each other, to the vehicle elec-
trical system and to the turn signal and hazard
warning system components through the use of a
combination of soldered splices, splice block connec-
tors and many different types of wire harness termi-
nal connectors and insulators. 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.
OPERATION - TURN SIGNAL & HAZARD
WARNING SYSTEM
The turn signal system operates on battery current
received on a fused ignition switch output (run-acc)
circuit so that the turn signals will only operate with
the ignition switch in the On or Accessory positions.
The hazard warning system operates on non-
switched battery current received on a fused B(+) cir-
cuit so that the hazard warning remains operational
8L - 2 LAMPS/LIGHTING - EXTERIORBR/BE

(9) Disconnect the instrument panel wire harness
connector for the multi-function switch from the
switch connector receptacle. Check for continuity
between the hazard flasher signal circuit cavities in
the JB receptacle for the combination flasher and the
instrument panel wire harness connector for the
multi-function switch. There should be continuity. If
OK, go to Step 10. If not OK, repair the open hazard
flasher signal circuit between the JB and the multi-
function switch as required.
(10) Check for continuity between the flasher out-
put circuit cavities of the JB receptacle for the com-
bination flasher and in the instrument panel wire
harness connector for the multi-function switch.
There should be continuity. If OK, test the multi-
function switch. (Refer to 8 - ELECTRICAL/LAMPS/
LIGHTING - EXTERIOR/MULTI-FUNCTION
SWITCH - DIAGNOSIS AND TESTING). If not OK,
repair the open flasher output circuit between the JB
and the multi-function switch as required.
SPECIFICATIONS
EXTERIOR LAMPS
LAMP BULB
Back-up 3157
Cargo 921
Center High Mounted
Stop921
Clearance Roof Mounted 168
Fog Lamps 896
Headlamp - SLT 9004LL
Headlamp - Sport Low
Beam9007
Headlamp - Sport High
Beam9004LL
License Plate w/o
Bumper1155
License Plate -Step
Bumper168
Park/Turn Signal 3157NA
Snow Plow Control 161
Tail/Brake/Turn Signal 3157
Tail/Brake/Cab - Chassis 1157
Underhood 105
SPECIAL TOOLS
HEADLAMP ALIGNMENT
BRAKE LAMP SWITCH
DESCRIPTION
The plunger type brake lamp switch is mounted on
a bracket attached to the brake pedal support under
the instrument panel.
CAUTION: The switch can only be adjusted during
initial installation. If the switch is not adjusted prop-
erly a new switch must be installed.
OPERATION
The brake lamp switch is used for the brake lamp,
speed control brake sensor circuits and electronic
brake distribution (EBD). The brake lamp circuit is
open until the plunger is depressed. The speed con-
trol and brake sensor circuits are closed until the
plunger is depressed.
When the brake light switch is activated, the Pow-
ertrain Control Module (PCM) receives an input indi-
cating that the brakes are being applied. After
receiving this input, the PCM maintains idle speed to
a scheduled rpm through control of the Idle Air Con-
trol (IAC) motor. The brake switch input is also used
to disable vent and vacuum solenoid output signals
to the speed control servo.
Vehicles equipped with the speed control option use
a dual function brake lamp switch. The PCM moni-
tors the state of the dual function brake lamp switch.
Refer to the Brake section for more information on
brake lamp switch service and adjustment proce-
dures.
The brake switch is equipped with three sets of
contacts, one normally open and the other two nor-
mally closed (brakes disengaged). The PCM sends a
12 volt signal to one of the normally closed contacts
in the brake switch, which is returned to the PCM as
a brake switch state signal. With the contacts closed,
the 12 volt signal is pulled to ground causing the sig-
nal to go low. The low voltage signal, monitored by
the PCM, indicates that the brakes are not applied.
When the brakes are applied, the contacts open,
Headlamp Aiming Kit C-4466±A
8L - 4 LAMPS/LIGHTING - EXTERIORBR/BE
LAMPS/LIGHTING - EXTERIOR (Continued)

DAYTIME RUNNING LAMP
MODULE
DESCRIPTION
The Daytime Running Lights (Headlamps) System
is installed on vehicles manufactured for sale in Can-
ada only. A separate module, mounted on the cowl,
controls the DRL.
OPERATION
The headlamps are illuminated when the ignition
switch is turned to the ON position. The DRL module
receives a vehicle-moving signal from the vehicle
speed sensor. This provides a constanthead-
lamps-oncondition as long as the vehicle is moving.
The lamps are illuminated at less than 50 percent of
normal intensity.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Disengage wire connector from DRLM (Fig. 8).
(3) Remove screws attaching DRLM to left front
inner fender panel.
(4) Separate DRLM from fender.
INSTALLATION
(1) Position DRLM on fender.(2) Install screws attaching DRLM to left front
inner fender panel.
(3) Engage wire connector to DRLM.
(4) Connect the battery negative cable.
FOG LAMP
DIAGNOSIS AND TESTING - FOG LAMP
CONDITION POSSIBLE CAUSES CORRECTION
FOG LAMPS ARE DIM
WITH ENGINE IDLING OR
IGNITION TURNED OFF.1. Loose or corroded battery cables. 1. Clean and secure battery cable clamps
and posts.
2. 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 Z33-ground. 6. Test for voltage drop across Z33-ground
locations.
FOG LAMP BULBS BURN
OUT FREQUENTLY1. Charging system output too high. 1. Test and repair charging system.
2. Loose or corroded terminals or
splices in circuit.2. Inspect and repair all connectors and
splices.
Fig. 8 Daytime Running Lamp Module (DRLM)
1 - HEADLAMP AND DASH WIRING HARNESS
2 - LEFT FENDER SIDE SHIELD
3 - DAYTIME RUNNING LAMP MODULE
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 9

CONDITION POSSIBLE CAUSES CORRECTION
FOG LAMPS ARE DIM
WITH ENGINE RUNNING
ABOVE IDLE1. Charging system output too low. 1. Test and repair charging system.
2. Poor lighting circuit Z33-ground. 2. Test for voltage drop across Z33-ground
locations.
3. High resistance in fog lamp circuit. 3. Test amperage draw of fog lamp circuit.
FOG LAMPS FLASH
RANDOMLY1. Poor lighting circuit Z33-ground. 1. Test for voltage drop across Z33-ground
locations.
2. High resistance in fog lamp circuit. 2. Test amperage draw of fog lamp circuit.
3. Faulty fog lamp switch. 3. Replace fog lamp switch.
4. Loose or corroded terminals or
splices in circuit.4. Inspect and repair all connectors and
splices.
FOG LAMPS DO NOT
ILLUMINATE1. Blown fuse for fog lamp. 1.Trace short and replace fuse.
2. No Z33-ground at fog lamps. 2. Repair circuit ground.
3. Faulty fog lamp switch. 3. Replace fog lamp switch.
4. Broken connector terminal or wire
splice in fog lamp circuit.4. Repair connector terminal or wire splice.
5. Defective or burned out bulb. 5. Replace bulb.
FOG LAMPS ARE
INOPERATIVE AND FOG
LAMP INDICATOR LIGHT
ALWAYS STAYS ON.1. Fog lamp/DRL* feed shorted to
ground.1. Check wiring circuit from fog lamp/DRL*
fuse to fog lamp. Trace short circuit in
wiring and repair.
FOG LAMPS ARE
INOPERATIVE AND FOG
LAMP INDICATOR LIGHT
IS ILLUMINATED.1. Fog lamp/DRL* fuse defective. 1. Trace short circuit and replace fuse.
2. Open circuit from fog lamp fuse to
fog lamp.2. Check wiring circuit from fog lamp/DRL*
fuse to fog lamp. Trace open circuit in
wiring and repair.
PARK LAMPS ARE
INOPERATIVE. FOG LAMP
INDICATOR IS ON WHEN
ALL SWITCHES ARE OFF
AND FUNCTIONS
OPPOSITE TO FOG
LAMPS.1. Park lamp feed is shorted. 1. Check wiring circuit from park lamp fuse
to headlamp switch. Trace short circuit in
wiring and repair.
PARK LAMPS ARE
INOPERATIVE. FOG LAMP
INDICATOR FUNCTIONS
OPPOSITE TO FOG
LAMPS.1. Park lamp fuse is defective. 1. Trace short circuit and replace fuse.
2. Open circuit from park lamp fuse
to headlamp switch.2. Check wiring circuit from park lamp fuse
to headlamp switch. Trace open circuit in
wiring and repair.
*Canada vehicles use Daytime Running Lamps (DRL).
8L - 10 LAMPS/LIGHTING - EXTERIORBR/BE
FOG LAMP (Continued)

Additional fog lamp diagnostic procedures listed are for vehicles equipped with quad headlamps and the DRL
option.
CONDITION POSSIBLE CAUSES CORRECTION
FOG LAMPS ARE INOPERATIVE
AND FOG LAMP INDICATOR
S TAY S A LWAY S O N .1 Fog lamp/DRL* feed shorted to
ground.1. Check wiring circuit from fog
lamp/DRL* fuse to fog lamp.Trace
short circuit in wiring and repair.
FOG LAMP INDICATOR COMES
ON WITH OUT ILLUMINATING THE
FOG LAMPS1. Fog lamp/DRL* fuse defective. 1. Trace short circuit and replace
fuse.
FOG LAMPS INOPERATIVE WITH
INGNITION OFF.Open circuit from fog lamp fuse to
fog lamp.1. Check wiring circuit from fog
lamp/DRL* fuse to fog lamp. Trace
open circuit in wiring and repair.
REMOVAL
(1) Disconnect and isolate the battery negative
cable.
(2) Disengage fog lamp harness connector.
(3) Rotate bulb assembly counterclockwise and
pull from lamp to separate (Fig. 9).
INSTALLATION
CAUTION: Do not touch the bulb glass with fingers
or other oily surfaces. Reduced bulb life will result.
(1) Position bulb assembly in lamp and rotate
clockwise.
(2) Connect fog lamp harness connector.
(3) Connect the battery negative cable.
FOG LAMP UNIT
REMOVAL
SLT
The fog lamps are serviced from the rearward side
of the front bumper.
(1) Disconnect and isolate the battery negative
cable.
(2) Disengage fog lamp harness connector.
(3) Remove fog lamp to bumper attaching nuts
(Fig. 10).
(4) Separate fog lamp from bumper.
Fig. 9 Fog Lamp
1 - NUT
2 - FOG LAMP ASSEMBLY
3 - UP/DOWN ADJUSTER
4 - BULB
5 - BUMPER
Fig. 10 Fog Lamp
1 - FOG LAMP
2 - BEAM ADJUSTER
3 - BUMPER
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 11
FOG LAMP (Continued)

HEADLAMP
DESCRIPTION
Headlamps on the Ram Pick-Up are modular in
design. The turn/park lamp module is incorporated
into the headlamp module. The module contains two
bulbs; a dual filament headlamp bulb, and a dual fil-
ament turn/park bulb. The Sport headlamp module
has two separate bulbs for the headlamp illumina-
tion.
OPERATION
Headlamps and parking lamps are controlled by
the headlamp switch. The multifunction switch
mounted on the steering column controls the high
beam function, and the turn signal function.
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.
Fig. 12 Fog Lamp Alignment
1 - VEHICLE CENTERLINE
2 - CENTER OF VEHICLE TO CENTER OF FOG LAMP LENS
3 - HIGH-INTENSITY AREA
4 - FLOOR TO CENTER OF FOG LAMP LENS5 - 100 mm (4 in.)
6 - 7.62 METERS (25 FEET)
7 - FRONT OF FOG LAMP
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 13
FOG LAMP UNIT (Continued)

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)
2. No ground for high and low beam
circuit.2. Ground should always be present
according to switch position. Check ground
at headlamp switch. Check wiring circuit
from headlamp switch to Multifunction
switch. Check headlamp switch and
Multifunction switch continuity. Repair circuit
ground.
3. Headlamp bulb(s) defective. 3. Replace bulb(s).
4. Faulty headlamp switch. 4. Replace headlamp switch.
5. Faulty headlamp dimmer
(Multifunction) switch.5. Replace Multifunction switch.
8L - 14 LAMPS/LIGHTING - EXTERIORBR/BE
HEADLAMP (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
6. Broken connector terminal or wire
splice in headlamp circuit.6. Repair connector terminal or wire splice.
HEADLAMPS (LOW
BEAM) DO NOT
ILLUMINATE.1. No ground for low beam circuit. 1. Ground should be present according to
Multifunction switch position. Check wiring
circuit from Multifunction switch to
headlamp . Trace open circuit in wiring and
repair.
Check Multifunction Switch for continuity.
HEADLAMPS (HIGH
BEAM) DO NOT
ILLUMINATE.1. No ground for high beam circuit. 1. Ground should be present according to
Multifunction switch position. Check wiring
circuit from Multifunction switch to
headlamp . Trace open circuit in wiring and
repair.
Check Multifunction Switch for continuity.
HEADLAMPS (LOW
BEAM) ALWAYS
ILLUMINATE AND CAN
NOT BE SHUT OFF.1. Low beam circuit from bulb to
Multifunction switch is shorted to
ground.1. Ground should be present according to
Multifunction switch position. Check wiring
circuit from Multifunction switch to
headlamp . Trace short circuit in wiring and
repair.
HEADLAMPS (HIGH
BEAM) ALWAYS
ILLUMINATE AND CAN
NOT BE SHUT OFF.1. High beam circuit from bulb to
Multifunction switch is shorted to
ground.1. Ground should be present according to
Multifunction switch position. Check wiring
circuit from Multifunction switch to
headlamp . Trace short circuit in wiring and
repair.
QUAD LAMPS DO NOT
ILLUMINATE AND HIGH
BEAMS ILLUMINATE.1. No voltage at either headlamp. 1. Voltage should always be present. Check
Quad lamp fuse. Check wiring circuit from
Quad lamp fuse to Quad lamp. Repeat for
left side
2. No ground for Quad beam circuit. 2. Ground should be present according to
Multifunction switch position. Check ground
at quad lamp relay. Check for battery
voltage at quad lamp relay. Check quad
lamp relay. Check relay control circuit (relay
coil to high beam).
3. If voltage and ground are present,
bulb(s) is defective.3.
Replace bulb(s).
HEADLAMP SWITCH OFF
HEADLAMPS AND
HIGHBEAM INDICATOR
REMAIN ON AND ARE
DIM.1. Headlamp switch feed circuit
shorted to ground.1. Check wiring circuit from right headlamp
fuse to headlamp. Repeat for left side.
Trace short circuit in wiring and repair.
HEADLAMP SWITCH ON
(LOW BEAMS ON), ONE
LOW BEAM ON AND
BOTH HIGH BEAMS DIM.1. Headlamp feed circuit shorted to
ground.1. Check wiring circuit from right headlamp
fuse to headlamp. Repeat for left side.
Trace short circuit in wiring and repair.
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 15
HEADLAMP (Continued)

CONDITION POSSIBLE CAUSES CORRECTION
HEADLAMP SWITCH ON
(HIGH BEAMS ON), ONE
HIGH BEAM ON AND
BOTH LOW BEAMS DIM.1. Headlamp feed circuit shorted to
ground.1. Check wiring circuit from right headlamp
fuse to headlamp. Repeat for left side.
Trace short circuit in wiring and repair.
HEADLAMP SWITCH ON,
ONE HEADLAMP
FILAMENT WILL BE AT
FULL INTENSITY AND ALL
OTHER FILAMENTS ARE
ON AND DIM.1. Blown headlamp fuse. 1. Trace short circuit and replace fuse.
2. Open circuit from headlamp fuse
to headlamp.2. Repair open headlamp circuit.
1. HEADLAMPS STAY ON
WITH KEY OUT (DRLM
EQUIPPED VEHICLES).1. Failed DRLM 1. Replace DRLM.
*Canada vehicles must have lamps ON.
REMOVAL
On the driver side, the battery and battery tray
must be removed to service the headlamp bulb.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the battery tray (Refer to 8 - ELEC-
TRICAL/BATTERY SYSTEM/TRAY - REMOVAL).
(3) Disengage wire connector from headlamp
bulb(s).
(4) Remove retaining ring holding bulb(s) to head-
lamp (Fig. 13).
(5) Pull bulb(s) from headlamp.
INSTALLATION
CAUTION: Do not touch the bulb glass with fingers
or other oily surfaces. Reduced bulb life will result.
(1) Position bulb(s) in headlamp.
(2) Install retaining ring holding bulb(s) to head-
lamp.
(3) Connect wire connector to headlamp bulb(s).
(4) Install battery tray, if removed (Refer to 8 -
ELECTRICAL/BATTERY SYSTEM/TRAY - INSTAL-
LATION).
(5) Connect battery negative cable.
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
Fig. 13 Headlamp Bulb
1 - BULB SOCKET
2 - BULB ASSEMBLY
3 - LOCK
4 - BULB RETAINING RING
5 - ELECTRICAL CONNECTOR
6 - UNLOCK
7 - PLASTIC BASE
8L - 16 LAMPS/LIGHTING - EXTERIORBR/BE
HEADLAMP (Continued)

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 electromagneticinterference 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
the PDC cover for headlamp relay identification and
location. 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.
(1) Remove the headlamp relay from the PDC.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR/HEADLAMP RELAY - REMOVAL).
(2) A relay in the de-energized position should
have continuity between terminals 87A and 30, and
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   5 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
Fig. 14 Power Distribution Center
1 - COVER
2 - POWER DISTRIBUTION CENTER
BR/BELAMPS/LIGHTING - EXTERIOR 8L - 17
HEADLAMP RELAY (Continued)