For 1990-2009 cars
Body Control Module Components
Body Control System Schematics

### Circuit Description

This is a trouble code (both current and history) that indicates the Automatic Lighting Control (ALC) parklamp relay output is shorted to the battery.

### Conditions for Setting the DTC

Meet all of the following conditions:

• | Turn the ignition switch to the RUN position.

• | The ALC option is enabled.

• | The ALC parklamp relay output is active.

• | The ALC parklamp feedback is not present for 1 second.

### Action Taken When the DTC Sets

• | Turns OFF the ALC parklamps

• | The check gauges chime sounds

• | Stores DTC B2588 in the body control module (BCM) memory

• | The SERVICE VEHICLE SOON indicator illuminates.

### Conditions for Clearing the DTC

• | The fault state is exited upon the program return to the ALC parklamp OFF state.

• | All of the body control module (BCM) history codes clear after 100 ignition cycles (from OFF to ON) with no current codes active during the 100 ignition cycles.

• | Use the Scan Tool scan tool.

### Diagnostic Aids

If the DTC is a history DTC, the problem may be intermittent. Perform the above tests while wiggling the wiring and connectors. This may often cause the malfunction to appear.

### Test Description

The numbers below refer to the numbers on the diagnostic table.

1. This step determines if the ALC parklamp relay is operating properly.

2. This step determines a short to the battery in CKT 1080 within the underhood wiring harness junction block.

3. This step determines a short to the battery in CKT 1080 between the Body Control Module (BCM) and the underhood wiring harness junction block.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: A short to ground will cause an open fuse(s). Before performing this diagnostic procedure, inspect the fuse(s) for an open.
1 | Was the Body Control Module (BCM) System Check performed? | -- | Go to Step 2 | Go to Body Control Module System Check
2 |

1. Replace the Automatic Lighting Control (ALC) parklamp relay with a known good relay on the underhood wiring harness junction block.
2. Use the scan tool in order to enable the ALC parklamp relay.

Did the ALC parklamp relay activate?

--

Go to Step 8

Go to Step 3

3 |

1. Remove the ALC parklamp relay from the underhood wiring harness junction block.
2. Disconnect the underhood wiring harness junction block connector C3.
3. Use the J 39200 Digital Multi Meter in order to measure the voltage in CKT 1080 between the underhood wiring harness junction block connector C3 terminal B8 and ground.

Does the measured voltage equal the specified value?

0 V

Go to Step 5

Go to Step 4

4 | Replace the underhood wiring harness junction block. Refer to Underhood Fuse Block Replacement in Engine Electrical. Is the repair complete? | -- | Go to Step 8 | --
5 |

1. Disconnect the BCM connector C1.
2. Use the J 39200 Digital Multi Meter in order to measure the voltage in CKT 1080 between the underhood wiring harness junction block harness connector C3 terminal B8 and ground.

Does the measured voltage equal the specified value?

0 V

Go to Step 6

Go to Step 7

6 | Replace the BCM. Refer to the following procedures:

• | Body Control Module (BCM) Programming/RPO Configuration

• | Body Control Module Replacement in Instrument Panel, Gauges and Console

Is the repair complete?

--

Go to Step 8

--

7 | Repair the short to B+ in CKT 1080 between the BCM connector C1 terminal B1 and the underhood wiring harness junction block harness connector C3 terminal B8. Is the repair complete? | -- | Go to Step 8 | --
8 | Clear the DTCs from the memory. Are the DTCs cleared from the memory? | -- | Go to Body Control Module System Check | --