Circuit Description
The Body Control Module (BCM) controls the park lamp relay. The BCM grounds the park lamp relay coil control circuit which in turns energizes the park lamp relay.
Conditions for Running the DTC
The BCM must not be commanding the Park Lamp relay to energize.
Conditions for Setting the DTC
| • | The BCM detects a short to ground or open in the park lamp relay coil control circuit when it is not trying to energize the Park Lamp relay. |
| • | The condition above must be present for more than 0.3 seconds. |
Action Taken When the DTC Sets
| • | The BCM stores DTC B2587 in memory. |
| • | The SERVICE VEHICLE SOON telltale illuminates. |
Conditions for Clearing the DTC
| • | A current DTC B2587 will clear if the short to ground or open in the park lamp relay coil control circuit is no longer detected by the BCM. |
| • | A history DTC B2587 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present. |
Diagnostic Aids
| • | If the DTC B2587 is a history DTC, the fault may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections |
| • | The following conditions may cause an intermittent malfunction to occur: |
| - | An intermittent short to ground or open in the park lamp relay coil control circuit. |
| - | The park lamp relay coil is intermittently shorted to ground or open internally |
| - | The BCM is intermittently shorted to ground or open internally |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
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Listen for an audible click when the park lamp relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
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Tests for voltage at the coil side of the park lamp relay. The LP Park fuse supplies power to the coil side of the park lamp relay.
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Verifies that the Body Control Module is providing ground to the park lamp relay.
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Tests if ground is constantly being applied to the park lamp relay.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Lighting System Diagnostic System Check? | -- | Go to Step 2 | |
Does the park lamp relay turn ON and OFF with each command? | -- | Go to Diagnostic Aids | Go to Step 3 | |
Does the test lamp illuminate? | -- | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | -- | Go to Step 8 | Go to Step 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 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 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 in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 |
8 | 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 13 | Go to Step 11 |
9 | Inspect for poor connections at the harness connector of the Body Control Module. 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 13 | Go to Step 12 |
10 | Repair a poor connection or an open in the park lamp relay coil feed. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair? | -- | Go to Step 13 | -- |
11 | Replace the park lamp relay. Did you complete the replacement? | -- | Go to Step 13 | -- |
12 |
Important: Perform the set up procedure for the body control module. Replace the BCM. Refer to Body Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- |
13 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
