For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Park Lamp Switch ON Signal | 2 | 2 | 2 | --
Park Lamp Relay Control | B2585 06 | B2585 06 | B2585 01 | --
License Lamp Control | 1 | 1 | 1 | --
Marker Lamp Control | 1 | 1 | 1 | --
Park Lamp Control | 1 | 1 | 1 | --
License Lamp Ground | -- | 1 | -- | --
Marker Lamp Ground | 1 | 1 | -- | --
Park/Turn Lamp - LF Ground | -- | 1 | -- | --
Park/Turn Lamp - RF Ground | -- | 1 | -- | --
Tail/Stop and Turn Signal Lamps - LR Ground | -- | 1 | -- | --
Tail/Stop and Turn Signal Lamps - RR Ground | -- | 1 | -- | --
Turn Signal/Multifunction Switch Ground | -- | 2 | -- | --
1. Park, License, Marker, and/or Tail Lamps Malfunction 2. Park Lamp Switch Malfunction

### Circuit/System Description

Battery voltage is applied at all times to the coil and switch sides of the PRK LAMPS relay located in the underhood fuse block. Ground is applied at G300 to the turn signal/multifunction switch at all times. When the headlamp switch is placed in either the HEAD or PARK position, ground is applied to the park lamp switch signal circuit to the body control module (BCM). The BCM reacts to the signal from the park lamp switch by applying ground to the park lamp relay control circuit. This energizes the park lamp relay allowing voltage to flow from the PRK LAMPS fuse through the switch contacts of the relay to all park, tail, license, and side marker lamps. Ground for the front park and side marker lamps is supplied at G101 for the left and G102 for the right. Ground for the license and right rear tail lamps is supplied at G402, and the left rear tail lamps at G400.

### Reference Information

#### 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

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, observe the scan tool Park Lamp Switch parameter while cycling the park lamp switch between the ON and OFF positions. The parameter should change between Active and Inactive.

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

⇒ | If the parameter changes between the commanded states, refer to Park, License, Marker, and/or Tail Lamps Malfunction.

### Circuit/System Testing

#### Park Lamp Switch Malfunction

1. Ignition OFF, disconnect the X1 harness connector at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 1.

⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool Park Lamp Switch parameter is Inactive.

⇒ | If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.

4. Install a 3A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Park Lamp Switch parameter is Active.

⇒ | 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 BCM.

5. If all circuits test normal, test or replace the turn signal/multifunction switch.

#### Park, License, Marker, and/or Tail Lamps Malfunction

1. Ignition OFF, disconnect the park lamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground.

⇒ | If the test lamp illuminates, test the control circuit for a short to voltage.

3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the park lamp relay.

4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground.

⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

5. Disconnect the harness connector at the inoperative park/marker, or license lamp.
6. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit and ground

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

7. Connect the harness connector at the inoperative park/marker, or license lamp.
8. Connect a 15A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the park lamps illuminate.

⇒ | If the park lamps do not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the inoperative park lamp.

9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Parks Lamps 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 ground. If the circuit tests normal, replace the BCM.

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

11. If all circuits test normal, test or replace the park lamp relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Parking and Turn Signal Lamp Replacement

• | Tail Lamp Replacement

• | Rear License Lamp Replacement

• | Relay Replacement

• | Turn Signal Multifunction Switch Replacement

• | Front Side Marker Lamp Replacement

• | Control Module References for BCM replacement, setup, and programming