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 | 1 | 1 | B2585 00 | -- |
Park Lamp Control | 1 | 1 | 1 | -- |
License Lamp Ground | -- | 1 | -- | -- |
Park Lamps - LF Ground | -- | 1 | -- | -- |
Park Lamps - RF Ground | -- | 1 | -- | -- |
Tail/Stop Lamps - LR Ground | -- | 1 | -- | -- |
Tail/Stop Lamps - RR Ground | -- | 1 | -- | -- |
Headlamp Switch Ground | -- | 2 | -- | -- |
1. Park, License, and/or Tail Lamps Malfunction 2. Park Lamp Switch Malfunction | ||||
Circuit/System Description
Battery voltage is applied at all times to both the coil and switch sides of the PARK LAMP relay located in the underhood fuse block. The headlamp switch is suppled with ground at G201 at all times. When the headlamp switch is placed in either the HEAD or PARK position, ground is applied to the park lamp signal circuit to the body control module (BCM). The BCM responds by applying ground to the park lamp relay control circuit. This energizes the park lamp relay coil causing the relay switch contacts to close allowing battery voltage to flow through the T/LAMP LT and T/LAMP RT fuses to all of the park, tail, license, and marker lamps.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool Parklamp Switch parameter while cycling the park lamp switch ON and OFF. 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, and/or Tail Lamps Malfunction. |
Circuit/System Testing
Park Lamp Switch Malfunction
- Ignition OFF, disconnect the harness connector at the headlamp switch.
- Ignition OFF, verify a test lamp illuminates between B+ and the ground circuit terminal 4.
- Ignition ON, verify the scan tool Parklamp Switch parameter is Inactive.
- Install a 3A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Parklamp Switch parameter is Active
- If all circuits test normal, test or replace the headlamp switch.
| ⇒ | If the test lamp does not illuminate, test the ground circuit for an open/high resistance. |
| ⇒ | If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | 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. |
Park, License, and/or Tail Lamps Malfunction
- Ignition OFF, remove the fuse of the inoperative park/marker lamps and inspect.
- Install the fuse.
- Ignition OFF, disconnect the park lamp relay.
- Ignition ON, verify a test lamp does not illuminate between the control circuit terminal 87 and ground.
- Verify a test lamp illuminates between the B+ circuit terminal 30 and ground.
- Verify a test lamp illuminates between the B+ circuit terminal 85 and ground.
- Disconnect the harness connector at the inoperative park/license/marker lamp.
- Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal and ground.
- Connect the harness connector at the inoperative park/license/marker lamp.
- Connect a 20A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the park/license/marker lamps illuminate.
- Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
- Command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.
- If all circuits test normal, test or replace the park lamp relay.
| ⇒ | If the fuse is OPEN, test the control circuit of the blown fuse for a short to ground. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. |
| ⇒ | 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. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the park/license/marker lamps do not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the inoperative park/license/marker lamp. |
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
