Circuit Description
The daytime running lights (DRL) relay is controlled by the body control module (BCM). Battery positive voltage is applied to the relay coil at all times. The BCM grounds the DRL relay control circuit in order to turn ON the DRL relay. When the DRL relay control circuit becomes shorted to ground or the DRLs remain illuminated without being commanded on by the BCM, DTC B2601 is set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2601 Daytime Running Lamp Control Circuit Low
Conditions for Running the DTC
| • | The ignition switch is in the ON position. |
| • | The headlamp switch is in the OFF position. |
| • | The transaxle is in park. |
Conditions for Setting the DTC
All of the following conditions must be met:
| • | The BCM is not commanding the DRL relay on. |
| • | The headlamp feedback is present for 5 seconds. |
Action Taken When the DTC Sets
| • | The BCM disables the DRL relay control as long as the malfunction is present. |
| • | The SERVICE indicator illuminates. |
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. |
Diagnostic Aids
| • | If DTC B2602 is set along with DTC B2601, test the DRL relay control circuit between the BCM and the DRL relay for a short to ground. |
| • | The park brake must be unapplied and the transaxle must be in gear for the DRLs to operate properly. |
| • | Intermittent malfunctions are cumulative. When the malfunction exists for a total of 5 seconds, DTC B2601 is set. |
| • | If the DTC is a history DTC, the problem may be intermittent. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step determines if a short to ground in the DRL relay control circuit or an open or high resistance in the left hand headlamp supply voltage circuit is causing DTC 2601 to set. A short to ground in the DRL relay control circuit will cause the DRLs to be on in this step. An open or high resistance in the left hand headlamp supply voltage circuit will cause the DRLs to not be illuminated in this step.
-
This step determines if the BCM has an internal short to ground.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
Are the DRLs illuminated? | Go to Step 3 | Go to Step 5 | |
Did you find and correct the condition? | Go to Step 7 | Go to Step 4 | |
4 | Inspect for poor connections at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
5 | Repair an open or high resistance in the left hand headlamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | -- |
6 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 7 | -- |
7 |
Does the DTC reset? | Go to Step 2 | System OK |
