B2600

DTC B2600

CIRCUIT DESCRIPTION
The ambient light sensor is a light sensitive transistor that sends a variable voltage signal to the body control module (BCM) in response to the exterior light level. The BCM energizes the daytime running lamp (DRL) relays by grounding the DRL relay control circuits. The DRL operate when the ambient light sensor indicates daytime, the ignition switch is in the RUN position, the gear selector is not in the park or neutral position, and the parking brake is released.

DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC B2600 Daytime Running Lamp Control Circuit

CONDITIONS FOR RUNNING THE DTC
The battery voltage must be between 9-16 volts.

CONDITIONS FOR SETTING THE DTC
- When the BCM sends a DRL OFF command and one of the DRL relay control circuits are shorted to ground
- When the BCM sends a DRL ON command and one of the DRL relay control circuits are shorted to voltage or open
- When the DRL diode supply voltage circuit is shorted to ground
- When the battery positive supply voltage circuit is shorted to ground or open

ACTION TAKEN WHEN THE DTC SETS
The DRL will not operate or will remain always ON.

CONDITIONS FOR CLEARING THE MIL/DTC
- This DTC will clear on current status after the condition for setting the fault is corrected.
- A history DTC will clear after 100 consecutive ignition cycles without a fault present.
- History and current DTCs can be cleared using a scan tool.

TEST DESCRIPTION

Step 1 - Step 13:

The numbers below refer to the step numbers on the diagnostic table.
2. Listen for an audible click when the DRL relays operate. Command both the ON and OFF states. Repeat the commands as necessary.
3. This step tests for voltage at the coil side of the DRL relays.
4. This step verifies that the BCM is providing ground to the DRL relays.
5. This step tests if ground is constantly being applied to the DRL relays.
6. This step tests if there is opposing voltage present or an open in the DRL relay control circuits.
12. After replacement of the BCM you must calibrate the new module for proper operation.