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 |
|---|---|---|---|---|
Parklamp Control Circuit | B2587 | B2587 | B2588 | -- |
Headlamp Switch Parklamp Signal Circuit | 1 | 2 | -- | -- |
Headlamp Switch Parklamp Ground Circuit | -- | 2 | 2 | -- |
Headlamp Switch | 1 | 2 | 2 | -- |
1. Parklamp Always ON 2. Parklamp Inoperative | ||||
Circuit/System Description
The body control module (BCM) controls the park lamp relay be grounding the control circuit on the park lamp relay when the headlamp switch is turned to the PARK or the HEAD position. This energizes the park lamp relay, illuminating the park lamps.
Diagnostic Aids
A short to ground, a short to voltage or an open in the following location may cause a malfunction to occur:
| • | The park lamp relay control circuit |
| • | The park lamp relay |
| • | The headlamp switch supply circuit |
| • | The headlamp switch ground circuit |
| • | The headlamp switch |
| • | The BCM |
Reference Information
Schematic Reference
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Ignition ON, turn the headlamps ON with the headlamp switch. Observe the park lamps, the park lamps should be ON.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the inoperative lamp.
- Ignition OFF, test for less than 1 ohm of resistance between the ground circuit and ground.
- Install test lamp between the signal circuit and ground. Verify that the parklamps are ON.
- If all circuits test normal, test or replace the inoperative light bulb.
| ⇒ | If greater than 1 ohm, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp is not ON, test the signal circuit of the headlamp switch for a short to ground or an open/high resistance. If circuit tests normal, replace the BCM. |
Component Testing
- Ignition OFF, disconnect the harness connector at the inoperative component.
- Test for less than 5 ohms between the signal terminal and the voltage supply terminal.
| ⇒ | If greater than 5 ohms, replace the inoperative light bulb. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
