Page 473 of 4284

TEST ACTION APPLICABILITY
3 Turn the ignition off.
Disconnect either rear tail lamp harness connector.
Turn the ignition on.
Engage the transmission to reverse.
Using a 12-volt test light connected to ground, check the Backup Lamps Output
circuit.
Does the test light illuminate brightly?All
Ye s®Replace the applicable Backup Lamp.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 4
4 Turn the ignition off.
Disconnect the IPM harness connector.
Measure the resistance of the Backup Lamp Output Circuit and ground.
Is the resistance below 5.0 ohms?All
Ye s®Refer to symptom list for problems related to Trans Range Sensor.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 5
5 Turn the ignition off.
Disconnect the Body Control Module harness connector.
Measure the resistance of the Backup Lamp Driver Circuit to ground.
Is the resistance above 5.0 ohms?All
Ye s®Repair the Backup Lamp Driver Circuit for an open condition.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 6
6 Turn the ignition off.
Disconnect the Body Control Module harness connector.
Disconnect the FCM from the IPM.
Measure the resistance of the Backup Lamp Driver Circuit and ground.
Is the resistance below 5.0 ohms?All
Ye s®Replace the Body Control Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Front Control Module.
Perform BODY VERIFICATION TEST - VER 1.
444
EXTERIOR LIGHTING
BACKUP LAMP OUTPUT OPEN ÐContinued
Page 474 of 4284

Symptom:
BACKUP LAMP OUTPUT SHORT
When Monitored and Set Condition:
BACKUP LAMP OUTPUT SHORT
When Monitored: Anytime the Body Control Module is active.
Set Condition: When voltage output status is Low.
POSSIBLE CAUSES
INTERMITTENT CONDITION
BACKUP LAMP
BACKUP LAMP DRIVER CIRCUIT SHORT TO GROUND
BODY CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, clear all BCM DTC's.
Actuate the Backup Lamps.
With the DRBIIIt, read the DTC information.
Does the DRBIIItread: Backup Lamp Output Short?All
Ye s®Go To 2
No®The condition that caused the symptom is currently not present.
Inspect the related wiring for a possible intermittent condition.
Look for any chafed, pierced,pinched, or partially broken wires.
Perform BODY VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Disconnect the rear tail lamp harness connector.
Turn the ignition on.
Actuate the Backup Lamps.
Using a 12-volt test light connected to ground, check the Backup Lamp Output
circuit.
Does the test light illuminate brightly?All
Ye s®Replace the Backup Lamp.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
3 Turn the ignition off.
Disconnect the Body Control Module harness connector.
Disconnect the rear tail lamp harness connector.
Measure the resistance of the Backup Lamp Driver circuit and ground.
Is the resistance below 5.0 ohms?All
Ye s®Repair the Backup Lamp Driver circuit for a short to ground.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Body Control Module.
Perform BODY VERIFICATION TEST - VER 1.
445
EXTERIOR LIGHTING
Page 475 of 4284

Symptom:
FRONT FOG LAMP RELAY OPEN
When Monitored and Set Condition:
FRONT FOG LAMP RELAY OPEN
When Monitored: Ignition On.
Set Condition: The IPM detects high current from the fog lamp relay control circuit.
POSSIBLE CAUSES
MISSING RELAY
OPEN FUSE
FOG LAMP RELAY
INTERMITTENT CONDITION
FOG LAMP RELAY CONTROL CIRCUIT OPEN
FRONT CONTROL MODULE
INTELLIGENT POWER MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, clear all IPM DTC's.
Turn the Fog Lamps on.
With the DRBIIIt, read the DTC information.
Does the DRBIIItread: Front Fog Lamp Relay Open?All
Ye s®Go To 2
No®Go To 5
2 Turn the ignition off.
Check the IPM to make certain the Fog Lamp Relay is present.
Is the Fog Lamp Relay present?All
Ye s®Go To 3
No®Replace the missing Fog Lamp Relay.
Perform BODY VERIFICATION TEST - VER 1.
3 Turn the ignition off.
Install a known good relay in place of the fog lamp relay.
Turn the Fog Lamps On.
Do the Fog Lamps operate normally?All
Ye s®Replace the Fog Lamp Relay.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 4
446
EXTERIOR LIGHTING
Page 476 of 4284

TEST ACTION APPLICABILITY
4 Turn the ignition off
Remove the Fog Lamp Relay.
Measure the voltage of the Fused B+ circuit of the fog lamp relay.
Is the voltage above 10 volts?All
Ye s®Replace the Front Control Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Intelligent Power Module.
Perform BODY VERIFICATION TEST - VER 1.
5 Turn the ignition off.
Check the IPM Fog Lamp fuse #1.
Is the fuse open?All
Ye s®Replace the open fuse.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 6
6 Turn the ignition off.
Disconnect the Front Control Module from the IPM.
Remove the Fog Lamp Relay.
Measure the resistance of the Fog Lamp Relay Control Circuit.
Is the resistance below 5.0 ohms?All
Ye s®The condition that caused the symptom is currently not present.
Inspect the related wiring for a possible intermittent condition.
Look for any chafed, pierced,pinched, or partially broken wires.
Perform BODY VERIFICATION TEST - VER 1.
No®Repair the Fog Lamp Relay Control Circuit.
Perform BODY VERIFICATION TEST - VER 1.
447
EXTERIOR LIGHTING
FRONT FOG LAMP RELAY OPEN ÐContinued
Page 477 of 4284

Symptom:
FRONT FOG LAMP SHORTED TO BATTERY
When Monitored and Set Condition:
FRONT FOG LAMP SHORTED TO BATTERY
When Monitored: Ignition On.
Set Condition: When a battery fault condition is present.
POSSIBLE CAUSES
INTERMITTENT CONDITION
FOG LAMP RELAY
FRONT CONTROL MODULE
INTELLIGENT POWER MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, clear all IPM DTC's.
Turn the Fog Lamps on.
With the DRBIIIt, read the DTC information.
Does the DRBIIItread: Front Fog Lamp Shorted To Battery?All
Ye s®Go To 2
No®The condition that caused the symptom is currently not present.
Inspect the related wiring for a possible intermittent condition.
Look for any chafed, pierced,pinched, or partially broken wires.
Perform BODY VERIFICATION TEST - VER 1.
2 Turn the ignition off.
Remove and install a known good relay in place of the Fog Lamp Relay.
Do the Fog Lamps operate normally?All
Ye s®Replace the Fog Lamp Relay.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
3 Turn the ignition off.
Remove the Fog Lamp Relay from the IPM.
Remove the Front Control Module from the IPM.
Measure the voltage of the Fog Lamp Relay Control circuit and ground.
Is the voltage above 1.0 volts?All
Ye s®Replace the Intelligent Power Module.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Front Control Module.
Perform BODY VERIFICATION TEST - VER 1.
448
EXTERIOR LIGHTING
Page 478 of 4284

Symptom:
HEADLAMP SWITCH MISMATCH
When Monitored and Set Condition:
HEADLAMP SWITCH MISMATCH
When Monitored: Ignition ON
Set Condition: Headlamp switch is in Auto mode and the vehicle is not EC Mirror
equipped.
POSSIBLE CAUSES
VERIFY AUTO HEADLAMP SWITCH
INTERMITTENT WIRING AND CONNECTORS
BODY CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, record and erase DTC's.
Turn the headlamps to the Auto position.
With the DRBIIIt, read DTCs.
Does the DRBIIItdisplay HEADLAMP SWITCH MISMATCH?All
Ye s®Go To 2
No®Go To 4
2 Visually identify the Headlamp Switch type.
Does the Headlamp Switch Contain an Auto Headlamp position?All
Ye s®Replace the Auto Headlamp Switch with a non Auto Headlamp
Switch.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
3 If there are no possible causes remaining, view repair. All
Repair
Replace and program the Body Control Module in accordance with
the Service Information.
Perform BODY VERIFICATION TEST - VER 1.
4 The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this
circuit.
Wiggle the wiring while checking for shorts and open circuits.
Were there any problems found?All
Ye s®Repair as necessary.
Perform BODY VERIFICATION TEST - VER 1.
No®Test Complete.
449
EXTERIOR LIGHTING
Page 479 of 4284

Symptom:
HEADLAMP SWITCH OPEN
When Monitored and Set Condition:
HEADLAMP SWITCH OPEN
When Monitored: Ignition ON
Set Condition: A Sensor voltage is over 4.8 volts for more than .0625 seconds.
POSSIBLE CAUSES
INTERMITTENT WIRING AND CONNECTORS
HEADLAMP SWITCH MUX CIRCUIT OPEN
HEADLAMP SWITCH MUX RETURN CIRCUIT OPEN
HEADLAMP SWITCH OPEN
BODY CONTROL MODULE
TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIIIt, record and erase DTC's.
Turn the headlamps to the ON position.
With the DRBIIIt, read DTCs.
Does the DRBIIItdisplay HEADLAMP SWITCH OPEN?All
Ye s®Go To 2
No®Go To 5
2 Turn the ignition off.
Disconnect the Headlamp Switch harness connector.
Connect a jumper wire between the Headlamp Switch MUX circuit and the
Headlamp Switch MUX Return circuit in the Headlamp Switch harness connector.
Turn the ignition on.
With the DRB, select Body, Body Controller and read the Headlamp Switch volts.
Does the DRB Headlamp Switch Sensor voltage read less than 0.5 Volts?All
Ye s®Replace the Headlamp Switch in accordance with the Service
Information.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 3
450
EXTERIOR LIGHTING
Page 480 of 4284

TEST ACTION APPLICABILITY
3 Turn the ignition off to the lock position.
Disconnect the Body Control Module harness connector.
Disconnect the Headlamp Switch harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the Headlamp Switch MUX circuit from the Body Control
Module connector to the Headlamp Switch harness connector.
Is the resistance above 5.0 ohms?All
Ye s®Repair the Headlamp Switch MUX circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
No®Go To 4
4 Turn the ignition off to the lock position.
Disconnect the Body Control Module harness connector.
Disconnect the Headlamp Switch harness connector.
Note: Check connectors - Clean/repair as necessary.
Measure the resistance of the Headlamp Switch MUX Return circuit from the Body
Control Module connector to the Headlamp Switch harness connector.
Is the resistance above 5.0 ohms?All
Ye s®Repair the Headlamp Switch MUX Return circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
No®Replace the Body Control Module in accordance with the Service
Information.
Perform BODY VERIFICATION TEST - VER 1.
5 The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this
circuit.
Wiggle the wiring while checking for shorts and open circuits.
Were there any problems found?All
Ye s®Repair as necessary.
Perform BODY VERIFICATION TEST - VER 1.
No®Test Complete.
451
EXTERIOR LIGHTING
HEADLAMP SWITCH OPEN ÐContinued