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

### Circuit Description

This trouble code (both current and history) indicates that the Daytime Running Lamps (DRL) relay output is shorted to ground or open.

### Conditions for Setting the DTC

All of the following conditions must be met:

• | Ignition 3 is active.

• | The DRL relay is commanded OFF by the body control module (BCM).

• | The DRL feedback is present for 5 seconds.

### Action Taken When the DTC Sets

• | Stores DTC B2602 in the BCM memory.

• | The SERVICE VEHICLE SOON indicator illuminates.

• | The check gauges chime sounds.

### Conditions for Clearing the DTC

• | The BCM goes to sleep and reinitializes with the fault cleared.

• | All of the 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

• | With the ignition switch in the RUN position and the PARK/NEUTRAL position switch not in the PARK position, look for an open circuit between the BCM and the underhood wiring harness junction block.

• | 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 DRL Relay is operating properly.

2. This step determines a bad connection at the Body Control Module (BCM).

3. This stop determines an open in CKT 592 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 DRL relay with a known good relay on the underhood wiring harness junction bock.
2. Use the Scan Tool scan tool to enable the DRL relay.

Does the Automatic Lighting Control (ALC) work correctly?

--

Go to Step 10

Go to Step 3

3 |

1. Reconnect the original DRL relay on the underhood wiring arenas junction block.
2. Disconnect the underhood wiring harness junction block connector C3.
3. Use the J 39200 Digital Multi-Meter to measure the voltage in CKT 592 between the underhood wiring harness junction block connector C3 terminal B12 and ground.

Is the measured voltage equal to the specified value?

B+

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 10 | --
5 |

1. Disconnect the BCM connector C1.
2. Use the J 39200 Digital Multi-Meter to measure the resistance in CKT 592 between the BCM connector C1 terminal B5 and ground.

Is the measured resistance equal to the specified value?

∞

Go to Step 7

Go to Step 6

6 | Repair the short to ground in CKT 592 between the BCM connector C1 terminal B5 and the underhood wiring harness junction block connector C3 terminal B12. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 10 | --
7 | Use the J 39200 Digital Multi-Meter to measure the resistance in CKT 592 between the BCM connector C1 terminal B5 and the underhood wiring harness junction block connector C3 terminal B12. Is the measured resistance within the specified range? | 0-2 ohms | Go to Step 9 | Go to Step 8
8 | Repair the open in CKT 592 between the BCM connector C1 terminal B5 and the underhood wiring harness junction block connector C3 terminal B12. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 10 | --
9 | Replace the BCM. Refer to the Body Control Module (BCM) Programming/RPO Configuration and BCM Replacement. Is the repair complete? | -- | Go to Step 10 | --
10 | Clear the DTCs from the memory. Are the DTCs cleared from the memory? | -- | Go to Body Control Module System Check | --