Circuit Description
The body control module (BCM) turns ON the park lamp relay when the ambient light sensor senses a dark condition. Battery positive voltage is supplied to the park lamp relay at all times through the PARK fuse. The BCM grounds the park lamp relay control circuit in order to activate the relay.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2587 Park Lamp Control Circuit Low
Conditions for Running the DTC
| • | The ignition switch is in the RUN position. |
| • | The headlamp switch is in the AUTO position. |
| • | The ambient light sensor senses a light condition, automatic lamp control (ALC) is commanding the park lamps OFF. |
Conditions for Setting the DTC
The following condition will set this DTC:
The park lamp relay control circuit is shorted to ground or open for 5 seconds.
Action Taken When the DTC Sets
| • | The park lamps will remain illuminated if shorted to ground. |
| • | The park lamps will not illuminate if open. |
Conditions for Clearing the DTC
| • | The BCM receives the clear code command from the scan tool. |
| • | A current DTC will clear when the conditions for setting the DTC are no longer present. |
| • | A history DTC clears after 100 malfunction free ignition cycles. |
Diagnostic Aids
If the DTC is a history DTC, the problem may be intermittent. 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.
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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 PARK fuse supplies battery positive voltage to the coil side of the park lamp relay.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Exterior Lights Schematics | |||
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 park lamp relay turn ON and OFF with each command? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
Does the test lamp illuminate? | Go to Step 4 | Go to Step 10 | |
4 |
Does the test lamp turn on and off? | Go to Step 8 | Go to Step 5 |
5 | Is the test lamp illuminated? | Go to Step 6 | Go to Step 7 |
6 | Test for a short to ground in the control circuit of the park lamp relay. 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 for an open or high resistance in the control circuit of the park lamp relay. 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 (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 13 | Go to Step 12 |
10 | Repair an open, high resistance, or short to ground in the coil side battery positive voltage circuit of the park lamp relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | -- |
11 | Replace the park lamp relay. Refer to Relay Replacement in Wiring Systems. Did you complete the replacement? | Go to Step 13 | -- |
12 | 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 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
