Circuit Description
The body control module (BCM) monitors the voltage on the interior park lamps fused supply voltage circuit in order to determine the actual state of the park lamp relay. The BCM also uses the park lamp relay control circuit in order to energize the park lamp relay.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2585 Parklamp Control Circuit
Conditions for Running the DTC
| • | The key is in the RUN position. |
| • | The park brake is released. |
| • | The headlamp and panel dimmer switch is in the AUTO mode. |
| • | The ambient light sensor is in the DARK state. |
| • | The system voltage must be between 9-16 volts. |
Conditions for Setting the DTC
| • | The key is in the RUN position. |
| • | The park brake is released. |
| • | The headlamp and panel dimmer switch is in the AUTO mode. |
| • | The ambient light sensor is in the DARK state. |
| • | There is a short to ground in the interior park lamps fused supply voltage circuit or an open in the park lamp relay control circuit. |
| • | If the interior park lamp fused supply voltage circuit is open, regardless of the headlamp and panel dimmer switch position, the DTC will set. |
| • | If the park lamp relay control circuit is open, with the headlamp and panel dimmer switch in the AUTO mode, the DTC will set. |
| • | The system voltage must be between 9-16 volts. |
| • | The above conditions must be met for 0.5 second. |
Action Taken When the DTC Sets
The park lamps will be inoperative in the AUTO mode.
Conditions for Clearing the MIL/DTC
| • | A current DTC will clear immediately when the condition for setting the fault is corrected with the key ON. |
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
| • | Use a scan tool in order to clear the history and current DTCs. |
Diagnostic Aids
Important: Use the appropriate probe from the J 35616 GM Terminal Test Kit for any probing of electrical components in this table, in order to prevent damage to them.
Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
Command both the ON and OFF states. Repeat the commands as necessary.
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This step determines if the condition is located on the coil side or the switch side of the circuit.
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This step determines if the body control module (BCM) is providing ground for the park lamp relay.
-
This step determines if a ground is constantly being applied to the park lamp relay.
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After you replace the BCM, you must calibrate the new module for proper operation.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Does the scan tool display ON and OFF in the Park Lamp Relay Outputs Data List with each command? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
With a scan tool, command the park lamp relay ON and OFF. Do you hear a click when you command the park lamp relay ON and OFF? | Go to Step 9 | Go to Step 4 | |
4 |
Does the test lamp illuminate? | Go to Step 5 | Go to Step 19 |
Does the test lamp turn ON and OFF with each command? | Go to Step 16 | Go to Step 6 | |
Does the test lamp remain illuminated with each command? | Go to Step 8 | Go to Step 7 | |
7 | Test the control circuit of the park lamp relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 17 |
8 | Test the control circuit of the park lamp relay for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 23 |
9 | Turn ON the ignition, with the engine OFF. Do the park lamps operate continuously? | Go to Step 10 | Go to Step 11 |
10 |
Do the park lamps operate continuously? | Go to Step 18 | Go to Step 22 |
11 |
Does the test lamp illuminate? | Go to Step 12 | Go to Step 20 |
12 | Connect a 3-amp fused jumper wire between the PARK LPS voltage circuit of the park lamp relay switch and the supply voltage circuit of the park lamps. Do the park lamps operate and does the scan tool display ON in the Park Lamp Relay Outputs Data List? | Go to Step 16 | Go to Step 13 |
13 | Test the park lamp switch output circuit and the fuse output- interior park lamp circuit for an open, high resistance, or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 14 |
14 | Test the ground circuit of the park lamps for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 15 |
15 | Inspect for poor connections at the headlamp panel dimmer switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 21 |
16 | Inspect for poor connections at the park lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 22 |
17 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 24 | Go to Step 23 |
18 | Repair the supply voltage circuit of the park lamps for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | -- |
19 | Repair the PARK LPS voltage circuit of the park lamp relay coil. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | -- |
20 | Repair the PARK LPS voltage circuit of the park lamp relay switch. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 24 | -- |
21 | Replace the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement . Did you complete the replacement? | Go to Step 24 | -- |
22 | Replace the park lamp relay. Refer to Relay Replacement in Wiring Systems. Did you complete the replacement? | Go to Step 24 | -- |
Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 24 | -- | |
24 | Operate the system in order to verify the repair. Did you correct the condition? | Go to Step 2 | System OK |
