2002 JEEP LIBERTY oil pressure sensor

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 Junction Block (JB). The inputs and
outputs of the front fog lamp relay include:
²Common Feed Terminal- The common feed
terminal (30) receives battery current at all times
from a fuse in the JB through a fused B(+) circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the pre-
mium Body Control Module (BCM) through a front
fog lamp relay control circuit. The BCM controls
front fog lamp operation by controlling a ground path
through this circuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the JB 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 current 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.
DIAGNOSIS AND TESTING - FRONT FOG LAMP
RELAY
The front fog lamp relay (Fig. 12) is located in the
Junction Block (JB) under the driver side outboard
end of the instrument panel. 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: 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 front fog lamp relay from the JB.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR/FRONT FOG LAMP RELAY - REMOV-
AL).
(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   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.
Fig. 12 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJLAMPS/LIGHTING - EXTERIOR 8L - 23
FRONT FOG LAMP RELAY (Continued)

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) From the face of the driver side inboard bezel,
align the headlamp leveling switch housing to the
mounting hole in the bezel (Fig. 36).
(2) Push the headlamp leveling switch into the
mounting hole until it is fully seated and the upper
latch and two lower latch features on the switch
housing are engaged on the back of the bezel.
(3) Position the switch and bezel unit to the
instrument panel.
(4) Reconnect the instrument panel wire harness
connector for the headlamp leveling switch to the
switch connector receptacle.
(5) Reinstall the driver side inboard bezel onto the
instrument panel. (Refer to 23 - BODY/INSTRU-
MENT PANEL/INSTRUMENT PANEL DRIVER
SIDE BEZEL - INSTALLATION).
(6) Reconnect the battery negative cable.
HEADLAMP LOW BEAM RELAY
DESCRIPTION
The headlamp low beam relay is located in the
Junction Block (JB) below the driver side outboard
end of the instrument panel in the passenger com-
partment of the vehicle. The headlamp low beam
relay is a conventional International Standards
Organization (ISO) micro relay (Fig. 37). Relays con-
forming to the ISO specifications have common phys-
ical dimensions, current capacities, terminal
patterns, and terminal functions. The relay is con-
tained within a small, rectangular, molded plastic
housing and is connected to all of the required inputs
and outputs by five integral male spade-type termi-
nals that extend from the bottom of the relay base.
The headlamp low beam relay cannot be adjusted
or repaired and, if faulty or damaged, the unit must
be replaced.
OPERATION
The headlamp low beam relay is an electromechan-
ical switch that uses a low current input from the
Body Control Module (BCM) to control a high current
output to the headlamp low beam filaments. 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 electro-
magnetic field is produced by the coil windings. This
electromagnetic field draws the movable relay con-
tact point away from the fixed normally closed con-
tact point, and holds it against the fixed normally
open contact point. When the relay coil is de-ener-
gized, 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 headlamp low beam relay terminals are con-
nected to the vehicle electrical system through a con-
nector receptacle in the Junction Block (JB). The
inputs and outputs of the headlamp low beam relay
include:
²Common Feed Terminal- The common feed
terminal (30) receives battery current at all times
from a fuse in the Power Distribution Center (PDC)
through a fused B(+) circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) receives battery current at all times from a
fuse in the PDC through a fused B(+) circuit.
Fig. 37 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJLAMPS/LIGHTING - EXTERIOR 8L - 39
HEADLAMP LEVELING SWITCH (Continued)

OPERATION
The rear fog lamp relay is an electromechanical
switch that uses a low current input from the Body
Control Module (BCM) to control a high current out-
put to the rear 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 rear fog lamp relay terminals are connected to
the vehicle electrical system through a connector
receptacle in the Junction Block (JB). The inputs and
outputs of the rear fog lamp relay include:
²Common Feed Terminal- The common feed
terminal (30) receives battery current at all times
from a fuse in the JB through a fused B(+) circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the pre-
mium Body Control Module (BCM) through a rear
fog lamp relay control circuit. The BCM controls rear
fog lamp operation by controlling a ground path
through this circuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the JB through a fused B(+) circuit.
²Normally Open Terminal- The normally open
terminal (87) is connected to the rear fog lamps
through a rear fog lamp relay output circuit and pro-
vides battery current to the rear fog lamps whenever
the relay is energized.
²Normally Closed Terminal- The normally
closed terminal (87A) is not connected in this appli-
cation.
The rear fog lamp relay can be diagnosed using
conventional diagnostic tools and methods.
DIAGNOSIS AND TESTING - REAR FOG LAMP
RELAY
The rear fog lamp relay (Fig. 57) is located in the
Junction Block (JB) under the driver side outboard
end of the instrument panel. 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 locationviews for the various wire harness connectors, splices
and grounds.
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 rear fog lamp relay from the JB.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR/REAR FOG LAMP 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   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
Fig. 57 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJLAMPS/LIGHTING - EXTERIOR 8L - 57
REAR FOG LAMP RELAY (Continued)

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 and is connected to all of the required inputs
and outputs by five integral male spade-type termi-
nals that extend from the bottom of the relay base.
The trailer tow relays cannot be adjusted or
repaired and, if faulty or damaged, the inoperative
relay must be replaced.
OPERATION
The trailer tow relays are electromechanical
switches. The relays each use an input from the cir-
cuit that they isolate from the trailer wiring to con-
trol a high current output to the trailer. 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 electro-
magnetic 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 terminals of each trailer tow relay are con-
nected to the vehicle electrical system through a con-nector bank in the rear lighting wire harness above
the right rear wheelhouse. 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. The trailer tow relays can be diagnosed
using conventional diagnostic tools and methods.
DIAGNOSIS AND TESTING - TRAILER TOW
RELAY
The trailer tow relays (Fig. 65) are located in a
connector bank above the right rear wheelhouse.
Refer to the appropriate wiring information. The wir-
ing 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: 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 trailer tow relay from the connec-
tor bank. (Refer to 8 - ELECTRICAL/LAMPS/LIGHT-
ING - EXTERIOR/TRAILER TOW 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   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, test the input and output circuits of
the relay. Refer to the appropriate wiring informa-
tion.
Fig. 64 Trailer Tow Relays
1 - RELAY CONNECTOR BANK
2 - REAR BODY WIRE HARNESS
3 - LEFT TURN RELAY
4 - RIGHT TURN RELAY
5 - BRAKE LAMP RELAY
6 - FUSED IGNITION SWITCH OUTPUT (RUN) RELAY
8L - 62 LAMPS/LIGHTING - EXTERIORKJ
TRAILER TOW RELAY (Continued)

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 Junction Block (JB). The inputs and
outputs of the front fog lamp relay include:
²Common Feed Terminal- The common feed
terminal (30) receives battery current at all times
from a fuse in the JB through a fused B(+) circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the pre-
mium Body Control Module (BCM) through a front
fog lamp relay control circuit. The BCM controls
front fog lamp operation by controlling a ground path
through this circuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the JB 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 current 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.
DIAGNOSIS AND TESTING - FRONT FOG LAMP
RELAY
The front fog lamp relay (Fig. 12) is located in the
Junction Block (JB) under the driver side outboard
end of the instrument panel. 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: 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 front fog lamp relay from the JB.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR/FRONT FOG LAMP RELAY - REMOV-
AL).
(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   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.
Fig. 12 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJLAMPS8Ls-23
FRONT FOG LAMP RELAY (Continued)

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) From the face of the driver side inboard bezel,
align the headlamp leveling switch housing to the
mounting hole in the bezel (Fig. 36).
(2) Push the headlamp leveling switch into the
mounting hole until it is fully seated and the upper
latch and two lower latch features on the switch
housing are engaged on the back of the bezel.
(3) Position the switch and bezel unit to the
instrument panel.
(4) Reconnect the instrument panel wire harness
connector for the headlamp leveling switch to the
switch connector receptacle.
(5) Reinstall the driver side inboard bezel onto the
instrument panel. (Refer to 23 - BODY/INSTRU-
MENT PANEL/INSTRUMENT PANEL DRIVER
SIDE BEZEL - INSTALLATION).
(6) Reconnect the battery negative cable.
HEADLAMP LOW BEAM RELAY
DESCRIPTION
The headlamp low beam relay is located in the
Junction Block (JB) below the driver side outboard
end of the instrument panel in the passenger com-
partment of the vehicle. The headlamp low beam
relay is a conventional International Standards
Organization (ISO) micro relay (Fig. 37). Relays con-
forming to the ISO specifications have common phys-
ical dimensions, current capacities, terminal
patterns, and terminal functions. The relay is con-
tained within a small, rectangular, molded plastic
housing and is connected to all of the required inputs
and outputs by five integral male spade-type termi-
nals that extend from the bottom of the relay base.
The headlamp low beam relay cannot be adjusted
or repaired and, if faulty or damaged, the unit must
be replaced.
OPERATION
The headlamp low beam relay is an electromechan-
ical switch that uses a low current input from the
Body Control Module (BCM) to control a high current
output to the headlamp low beam filaments. 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 electro-
magnetic field is produced by the coil windings. This
electromagnetic field draws the movable relay con-
tact point away from the fixed normally closed con-
tact point, and holds it against the fixed normally
open contact point. When the relay coil is de-ener-
gized, 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 headlamp low beam relay terminals are con-
nected to the vehicle electrical system through a con-
nector receptacle in the Junction Block (JB). The
inputs and outputs of the headlamp low beam relay
include:
²Common Feed Terminal- The common feed
terminal (30) receives battery current at all times
from a fuse in the Power Distribution Center (PDC)
through a fused B(+) circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) receives battery current at all times from a
fuse in the PDC through a fused B(+) circuit.
Fig. 37 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJLAMPS8Ls-39
HEADLAMP LEVELING SWITCH (Continued)

OPERATION
The rear fog lamp relay is an electromechanical
switch that uses a low current input from the Body
Control Module (BCM) to control a high current out-
put to the rear 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 rear fog lamp relay terminals are connected to
the vehicle electrical system through a connector
receptacle in the Junction Block (JB). The inputs and
outputs of the rear fog lamp relay include:
²Common Feed Terminal- The common feed
terminal (30) receives battery current at all times
from a fuse in the JB through a fused B(+) circuit.
²Coil Ground Terminal- The coil ground termi-
nal (85) is connected to a control output of the pre-
mium Body Control Module (BCM) through a rear
fog lamp relay control circuit. The BCM controls rear
fog lamp operation by controlling a ground path
through this circuit.
²Coil Battery Terminal- The coil battery ter-
minal (86) receives battery current at all times from
a fuse in the JB through a fused B(+) circuit.
²Normally Open Terminal- The normally open
terminal (87) is connected to the rear fog lamps
through a rear fog lamp relay output circuit and pro-
vides battery current to the rear fog lamps whenever
the relay is energized.
²Normally Closed Terminal- The normally
closed terminal (87A) is not connected in this appli-
cation.
The rear fog lamp relay can be diagnosed using
conventional diagnostic tools and methods.
DIAGNOSIS AND TESTING - REAR FOG LAMP
RELAY
The rear fog lamp relay (Fig. 57) is located in the
Junction Block (JB) under the driver side outboard
end of the instrument panel. 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 locationviews for the various wire harness connectors, splices
and grounds.
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 rear fog lamp relay from the JB.
(Refer to 8 - ELECTRICAL/LAMPS/LIGHTING -
EXTERIOR/REAR FOG LAMP 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   8 ohms. If OK, go to Step
4. If not OK, replace the faulty relay.
Fig. 57 ISO Micro Relay
30 - COMMON FEED
85 - COIL GROUND
86 - COIL BATTERY
87 - NORMALLY OPEN
87A - NORMALLY CLOSED
KJLAMPS8Ls-57
REAR FOG LAMP RELAY (Continued)

TRAILER TOW RELAY
DESCRIPTION
The trailer tow relays are located in a connector
bank above the right rear wheelhouse and behind the
quarter trim panel on vehicles equipped with the
optional factory-installed trailer towing package.
Four individual relays are used, one each for fused
ignition switch output (run), brake lamps, right turn
signal, and left turn signal outputs to a trailer
through the rear body wiring and connectors. The
trailer tow relays are conventional International
Standards Organization (ISO) micro relays (Fig. 64).
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 and is connected to all of the required inputs
and outputs by five integral male spade-type termi-
nals that extend from the bottom of the relay base.
The trailer tow relays cannot be adjusted or
repaired and, if faulty or damaged, the inoperative
relay must be replaced.
OPERATION
The trailer tow relays are electromechanical
switches. The relays each use an input from the cir-
cuit that they isolate from the trailer wiring to con-
trol a high current output to the trailer. 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 electro-
magnetic 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 terminals of each trailer tow relay are con-
nected to the vehicle electrical system through a con-
nector bank in the rear lighting wire harness above
the right rear wheelhouse. 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. The trailer tow relays can be diagnosed
using conventional diagnostic tools and methods.
DIAGNOSIS AND TESTING - TRAILER TOW
RELAY
The trailer tow relays (Fig. 65) are located in a
connector bank above the right rear wheelhouse.
Refer to the appropriate wiring information. The wir-
ing 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: 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.
Fig. 64 Trailer Tow Relays
1 - RELAY CONNECTOR BANK
2 - REAR BODY WIRE HARNESS
3 - LEFT TURN RELAY
4 - RIGHT TURN RELAY
5 - BRAKE LAMP RELAY
6 - FUSED IGNITION SWITCH OUTPUT (RUN) RELAY
8Ls - 62 LAMPSKJ