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 Description

Battery positive voltage is applied at all times to both the coil and switched sides of the DRL PCB Relay. 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 PCB relay coil. With the relay energized, voltage is applied through the switch side of the relay, both LOW BEAM Fuses, and the headlamp low beam supply voltage circuits to the low beam headlamps.

Conditions for Running the DTCs

* The headlamp switch is in the AUTO position.
* The transmission range selector is not in the PARK position.

Conditions for Setting the DTC

The BCM detect a short to voltage in the DRL relay control circuit.

Action Taken When the DTC Sets

The BCM will deactivate the DRL relay for the remainder of the ignition cycle.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information
Schematic Reference

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

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

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

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, command the DRLs ON with a scan tool. The DRL Relay Command parameter should display On and the DRLs should illuminate.

Circuit/System Testing

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 23 and B+.

• If the test lamp illuminates, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.

3. Install a 10A fused jumper wire between the control circuit terminal 23 and ground. The DRLs should illuminate.

• If the DRLs do not illuminate, test the 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.

* Accessory Wiring Junction Block Replacement (Accessory Wiring Junction Block Replacement)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming