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 | B257A 00 | B257A 00 | B257A 00 | --
Left Park Lamp Control | B2585 02 | B2585 04 | B2585 01 | --
Right Park Lamp Control | B3867 02 | B3867 04 | B3867 01 | --
Left Number Plate Light Control | 2 | 2 | 1 | --
Right Number Plate Light Control | 2 | 2 | 1 | --
Park Lamps Ground | -- | 2 | -- | --
Number Plate Lights Ground | -- | 4 | -- | --
1. Park lamps always On 2. Park lamps always Off 3. Number plate lights always On 4. Number plate lights always Off

### Circuit/System Description

The park lamps and number plate lights are turned ON when the headlamp switch is placed in the Parking lights or Low beam position or anytime the headlights are requested. When the body control module (BCM) receives an request to switch ON the park lamps and number plate lights the BCM provides a sends out a PWM signal, which illuminates the park lamps and number plate lights.

### 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

1. Command the park lamps ON and OFF using the headlamp switch. Verify the scan tool Park Lamp Switch parameter cycles between Active and Inactive as commanded.

⇒ | If the parameter does not cycle between the specified values, refer to Park Lamp Switch Malfunction.

2. Ignition ON, switch ON and OFF the park lamps and number plate lights by using the headlamp switch. Park lamps and number plate lights should go ON and OFF.

⇒ | If the park lamps are inoperative--Refer to Park Lamps Inoperative

⇒ | If the number plate lights are inoperative--Refer to Number Plate Lights Inoperative

⇒ | If the tail lamp are inoperative--Refer to Tail Lamps Inoperative

### Circuit/System Testing

#### Park Lamps Inoperative

1. Ignition OFF, disconnect the harness connector at the appropriate inoperative park lamp.
2. Test for less than 5 Ω between the appropriate park lamp ground circuit harness connector listed below and ground.

• | E4N Park/Turn Signal Lamp - Left ground circuit harness connector terminal 2

• | E4P Park/Turn Signal Lamp - Right ground circuit harness connector terminal 2

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

3. Connect a test lamp between the appropriate park lamp control circuit harness connector listed below and ground.

• | E4N Park/Turn Signal Lamp - Left ground circuit harness connector terminal 1

• | E4P Park/Turn Signal Lamp - Right ground circuit harness connector terminal 1

4. Ignition ON, switch ON and OFF the park lamps by using the headlamp switch. The test lamp should turn ON and OFF when changing between the ON/OFF states.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 Body Control Module (BCM).

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

#### Tail Lamps Inoperative

1. Ignition OFF, disconnect the harness connector at the appropriate inoperative tail lamp.
2. Test for less than 5 Ω between the appropriate tail lamp ground circuit harness connector listed below and ground.

• | E5E Tail Lamp - Left ground circuit harness connector terminal 2

• | E5F Tail Lamp - Right ground circuit harness connector terminal 2

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

3. Connect a test lamp between the appropriate tail lamp control circuit harness connector listed below and ground.

• | E5E Tail Lamp - Left control circuit harness connector terminal 1

• | E5F Tail Lamp - Right control circuit harness connector terminal 1

4. Ignition ON, switch ON and OFF the tail lamps by using the headlamp switch. The test lamp should turn ON and OFF when changing between the ON/OFF states.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 Body Control Module (BCM).

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

#### Number Plate Lights Inoperative

1. Ignition OFF, disconnect the harness connector at the number plate light.
2. Test for less than 5 Ω between the number plate light ground circuit terminal 1 and ground.

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

3. Connect a test lamp between the number plate light control circuit terminal 2 and ground.
4. Switch ON the parking lamps or low beam. The test lamp should be ON.

⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 Body Control Module (BCM).

⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the K9 Body Control Module (BCM).

5. If all the circuits test normal, replace the E7 License Lamp.

#### Park Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the S30 Headlamp Switch.
2. Verify that a test lamp illuminates between the ground circuit terminal 6 and B+.

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

3. Ignition ON, test for B+ between the park lamp signal circuit terminal 3 and ground.

⇒ | If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).

4. Install a 3 A fused jumper wire between the park lamp ON signal circuit terminal 3 and ground. Verify the scan tool Parklamp Switch parameter changes from Inactive to Active.

⇒ | If always Inactive, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module (BCM).

⇒ | If always active, test the signal circuit for a short to ground. If the circuit tests normal, replace the K9 Body Control Module (BCM).

5. If all circuits test normal, replace the S30 Headlamp Switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Rear License Plate Lamp Replacement

• | Tail Lamp Replacement

• | Tail Lamp Bulb Replacement

• | Headlamp Switch Replacement

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