The headlamp switch is supplied with voltage from the instrument panel cluster (IPC) by two signal circuits, the AUTO lamps signal circuit and the PARK lamp signal circuit. When the headlamp switch is placed in the PARK position, the park lamp signal circuit is provided with ground through the switch contacts of the park lamp switch to a common headlamp switch ground back to the IPC. The IPC interprets the flow of voltage and responds by sending a serial data message to the underhood electrical center (UEC) and the rear electrical center (REC) requesting the front and rear park lamps be activated. The UEC and REC respond by applying voltage to there respective park, marker, and license lamp control circuits illuminating the park, marker and license lamps.

Curb Side Parking Lamps

Curb side parking lamps is a feature that allows the vehicles owner to activate either the left or right side parks lamps while the vehicle is parked and the ignition is off. Curb side parking lamps is a European mandate and all vehicles sold in the United States will be programmed with it. This feature is software driven and cannot be changed or reprogrammed to illuminate it. To activate the curb side parking lamps the following conditions must be met:

1. Ignition OFF.
2. Turn signal switch placed in either the RIGHT or LEFT position.

When these conditions are met, the front and rear parking lamps for only the side selected will remain illuminated until the turn signal switch is placed in the neutral position or the ignition switch is cycled ON then OFF. This feature is not safe guarded by the vehicles battery rundown protection and in the event that the curb side parking feature is left ON, total battery discharge will occur. Upon activating the curb side parking lamps, an audible warning of three chimes will notify the vehicles owner that the feature is active.

Schematic Reference

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Parking Light Status parameter while cycling the park lamp switch ON and OFF. The parameter should change between ON and OFF.

⇒	If the parameter does not change between the commanded states, refer to Park Lamp Switch Malfunction.

2. Command the Front Parking Light Test ON and OFF with a scan tool. The front park lamps should turn ON and OFF when commanded.

⇒	If the front park lamps do not illuminate when commanded, refer to Front Park Lamps Malfunction.

3. Command the Rear Outer Combination Lamps Test ON and OFF with a scan tool. The rear park lamps should turn ON and OFF when commanded.

⇒	If the rear park lamps do not illuminate when commanded, refer to Rear Park Lamps Malfunction.

4. Command the License Plate Light Test ON and OFF with a scan tool. The license lamps should turn ON and OFF when commanded.

⇒	If the license lamps do not illuminate when commanded, refer to License Lamps Malfunction.

5. Command the Rear Side Markers Test ON and OFF with a scan tool. The front and rear side marker lamps should turn ON and OFF when commanded.

⇒	If the front and rear side marker lamps do not illuminate when commanded, refer to Side Marker Lamps Malfunction.

Park Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition OFF, verify a test lamp illuminates between B+ and the ground circuit terminal 11.

⇒	If the test lamp does not illuminate, test the ground circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.

3. Ignition ON, park lamps ON, verify the scan tool Parking Light Status parameter is Off.

⇒	If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the IPC.

4. Install a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Parking Light Status parameter is On.

⇒	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.

5. If all circuits test normal, replace the headlamp switch.

Front Park Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate headlamp assembly.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal 4 and ground.
4. Command the Front Parking Light Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the UEC.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the UEC.

5. If all circuits test normal, replace the inoperative front parking lamp.

Rear Park Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative rear tail lamp assembly.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground.

•	Left rear tail lamp ground terminal 1 - 3 Door

•	Left rear tail lamp ground terminal 6 - 5 Door

•	Right rear tail lamp ground terminal 6 - 3 Door

•	Right rear tail lamp ground terminal 1 - 5 Door

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the appropriate control circuit terminal listed below and ground.

•	Left rear park lamp control terminal 5

•	Right rear park lamp control terminal 2

4. Command the Rear Outer Combination Lamps Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the REC.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the REC.

5. If all circuits test normal, replace the inoperative tail lamp circuit board.

License Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative license lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal 2 and ground.
4. Command the License Plate Light Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the REC.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the REC.

5. If all circuits test normal, replace the inoperative license lamp.

Side Marker Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative side marker lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal 1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal 2 and ground.
4. Command the Rear Side Markers Test ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the REC.

⇒	If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the REC.

5. If all circuits test normal, replace the inoperative side marker lamp.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.