For 1990-2009 cars

Refer to Headlights/Daytime Running Lights (DRL) Schematics

### Circuit Description

The daytime running lamps (DRL) are controlled by the body control module (BCM). The BCM grounds circuit 592 in order to energize the DRL relay coil. This action places both low and high beam headlamps (Oldsmobile -- high beams only) in series with each other with the DRL relay terminal 87 providing ground and the RH HDLP fuse providing battery positive voltage. The BCM monitors the low (1201) and high (1200) beam circuits to ensure that the DRLs are operating properly. If the BCM senses that the DRLs are not operating properly, DTC B2600 is set.

### Conditions for Running the DTCs

• | The ignition switch is on.

• | The headlamp switch is off.

• | The park brake is unapplied.

• | The transaxle is in gear.

### Conditions for Setting the DTC

One or more of the following conditions is/are present:

• | Circuit 592 is open.

• | Circuit 593 is open.

• | Circuit 41 is open.

• | Circuit 640 is open.

• | Circuit 1200 is open.

• | Circuit 1201 is open (Pontiac only).

• | Circuit 150 is open.

• | A headlamp bulb filiment is open.

### Action Taken When the DTC Sets

The BCM turns off the DRL relay for the remainder of the ignition cycle.

### Conditions for Clearing the DTC

• | A current DTC B2600 clears when the malfunction is no longer present and the ignition switch is cycled.

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

### Diagnostic Aids

• | Diagnose all other DRL DTCs before DTC B2600.

• | An open headlamp bulb may set this DTC.

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

### Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

1. Listen for an audible click when the DRL relay operates. Command both the ON and OFF states. Repeat the commands as necessary.

2. Tests for voltage at the coil side of the DRL relay.

3. Verifies that the body control module is providing ground to the DRL relay.

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the DRL System Check? | Go to Step 2 | Go to Daytime Running Lights (DRL) System Check
2 | Inspect the HTR-A/C IGN fuse. Is the fuse open? | Go to Step 8 | Go to Step 3
3 | Inspect the RH HDLP fuse. Is the fuse open? | Go to Step 10 | Go to Step 4
4 |

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With a scan tool, command the DRL relay ON and OFF.

Does the DRL relay turn ON and OFF with each command?

Go to Step 12

Go to Step 5

5 |

1. Turn OFF the ignition.
2. Disconnect the DRL relay.
3. Turn ON the ignition, with the engine OFF.
4. Probe the coil side feed circuit of the DRL relay with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 17

6 |

1. Connect a test lamp between the control circuit of the DRL relay connector and the coil side feed circuit of the DRL relay connector.
2. With a scan tool, command the DRL relay ON and OFF .

Does the test lamp turn ON and OFF with each command?

Go to Step 18

Go to Step 7

7 | Test the control circuit of the DRL relay for an open. Did you find and correct the condition? | Go to Step 20 | Go to Step 15
8 | Test the coil side feed circuit of the DRL relay for a short to ground. Did you find and correct the condition? | Go to Step 20 | Go to Step 9
9 | Replace the HTR-A/C IGN fuse. Did you complete the replacement? | Go to Step 20 | --
10 | Test the right headlamp feed for a short to ground. Did you find and correct the condition? | Go to Step 20 | Go to Step 11
11 | Replace the RH HDLP fuse. Did you complete the replacement? | Go to Step 20 | --
12 | Test the ground feed of the DRL relay for an open. Did you find and correct the condition? | Go to Step 20 | Go to Step 13
13 | Test circuit 593 between the DRL relay and the left headlamp for an open. Did you find and correct the condition? | Go to Step 20 | Go to Step 14
14 | Test the following circuits for an open:

• | Circuit 1200

• | Circuit 1201 (Pontiac only)

Did you find and correct the condition?

Go to Step 20

Go to Step 15

15 | Inspect for poor connections at the harness connector of the body control module. Did you find and correct the condition? | Go to Step 20 | Go to Step 16
16 | Replace the body control module. Refer to BCM Replacement. Important: Perform the set up procedure for the body control module. Did you complete the replacement? | Go to Step 20 | --
17 | Repair the coil side feed circuit of the DRL relay. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 20 | --
18 | Inspect for poor connections at the DRL relay. Did you find and correct the condition? | Go to Step 20 | Go to Step 19
19 | Replace the DRL relay. Did you complete the replacement? | Go to Step 20 | --
20 |

1. Use the scan tool in order to clear the DTCs .
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK