Circuit Description
The body control module (BCM) controls the park lamp relay by grounding the control circuit of 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.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2587 Parklamp Control Circuit Low
Conditions for Running the DTC
Voltage supplied to the module is in the normal operating range, approximately 10-16 volts.
Conditions for Setting the DTC
| • | The BCM detects a short to ground or an open in the control circuit of the park lamp relay coil when the BCM is not commanding the park lamps ON. |
| • | The condition must be present for more than 3 ms. |
Action Taken When the DTC Sets
The BCM stores DTC B2587 in memory.
Conditions for Clearing the DTC
| • | A current DTC B2587 clears if the BCM no longer detects a short to ground or an open in the control circuit of the park lamp relay. |
| • | A history DTC B2587 clears after 100 consecutive ignition cycles. |
| • | The BCM receives the Clear Code commend from the scan tool. |
Diagnostic Aids
| • | If the DTC B2587 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections . |
| • | An intermittent short to ground or an open in the following locations may cause an intermittent malfunction to occur: |
| - | The control circuit of the park lamp relay |
| - | The park lamp relay |
| - | The BCM |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Master Electrical Component List | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the park lamp relay turn ON and OFF with each command? | Go to Diagnostic Aids | Go to Step 3 |
3 |
Does the test lamp illuminate? | Go to Step 4 | Go to Step 10 |
4 |
Does the test lamp turn ON and OFF with each command? | Go to Step 8 | Go to Step 5 |
5 | Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 6 |
6 | Test the control circuit of the park lamp relay for an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the park lamp relay for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
8 | Inspect for a poor connection at the park lamp relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
9 | Inspect for a high resistance or a poor connection at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
10 | Replace the underhood fuse block. Refer to Testing for Intermittent Conditions and Poor Connections . Did you complete the repair? | Go to Step 13 | -- |
11 | Replace the park lamp relay. Refer to Relay Replacement . Did you complete the replacement? | Go to Step 13 | -- |
12 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
