B2600

DTC B2600

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.



DTC Descriptor
DTC B2600 00
- Daytime Running Lamp Control Circuit




Diagnostic Fault Information






Circuit/System Description

The daytime running lamps (DRL) are controlled by the body control module (BCM). The BCM grounds the DRL relay control circuit in order to energize the DRL relay coil. The DRL relay then sends voltage to the dedicated DRL or low beam headlamps.


Conditions for Running the DTCs

* The headlamp switch is OFF.
* The park brake is unapplied.
* The engine is running.



Conditions for Setting the DTC

The DRL relay control circuit is shorted to voltage.


Action Taken When the DTC Sets

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


Conditions for Clearing the DTC

* The conditions for setting the DTC are no longer present.
* A history DTC clears after 100 malfunction-free ignition cycles.
* The BCM receives the clear code command from the scan tool.



Reference Information
Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics (Headlights/Daytime Running Lights (DRL) Schematics)
Connector End View Reference

Component Connector End Views (Component Connector End Views)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Programming and Relearning (Programming and Relearning)for Scan Tool Information


Circuit/System Verification

Block the drive wheels. Carefully supply sufficient light to simulate daylight conditions to the ambient light sensor. With the engine running, headlamp switch in AUTO, and the park brake released, the DRL should illuminate.


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector X4 at the BCM.
2. Ignition ON, verify the daytime running lamps are not on.

• If the daytime running lamps are on, test the DRL relay control circuit for a short to ground. If the circuit tests normal replace the underhood fuse block.

3. Install a 10A fused jumper wire between the relay control circuit terminal 23 and ground. Verify the daytime running lamps are on. are on.

• If the daytime running lamps are not on, test the DRL relay control circuit for a short to voltage or an open/high resistance. If the circuit tests normal replace the underhood fuse block.

4. If all circuits test normal, replace the BCM.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Underhood Electrical Center or Junction Block Replacement (Underhood Electrical Center or Junction Block Replacement)
* Programming and Relearning (Programming and Relearning)for BCM replacement, setup, and programming