B3949

DTC B3949

Diagnostic Instructions

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



DTC Descriptors
DTC B3949 02
- Right Front Turn Signal Circuit Short to Ground

DTC B3949 05
- Right Front Turn Signal Circuit Short to Battery or Open




Circuit/System Description

The body control module (BCM) controls the right front turn signal, hazard lamp, and daytime running lamp (DRL). The BCM supplies voltage to control the lighting functions. The BCM monitors the right turn signal lamp supply voltage circuit for proper operation.


Conditions for Setting the DTC

B3949 02

This DTC will set if there is a short to ground in the right front turn signal circuit.

B3949 05

This DTC will set if there is an open or short to voltage in the right front turn signal circuit.


Action Taken When the DTC Sets

* The Service Vehicle Soon message will be displayed.
* Stores a DTC B3949 in the BCM memory.
* If failure is open, short to ground, or to power, rear turn signal flashes at double rate.



Conditions for Clearing the DTC

* This DTC requires an ignition cycle in order to change from current to history.
* The BCM no longer detects continuous battery voltage on the RH turn signal monitor circuit for longer than 5 seconds.
* A history DTC will clear after 50 consecutive ignition cycles if the condition for the malfunction is no longer present.



Diagnostic Aids

* The following conditions may cause an intermittent malfunction:

- There is an intermittent short to voltage in the LH turn signal monitor circuit.
- The turn signal switch or the hazard switch is shorted internally or is sticking.

* If the BCM detects continuous voltage on the LH turn signal monitor circuit, the BCM interprets this as a short to voltage. The BCM will continue with normal DRL operation, and the LF turn signal will remain inoperative.
* A burned out bulb will cause a B3949 05 to set.



Reference Information
Schematic Reference

Exterior Lights Schematics (Exterior Lights Schematics)
Connector End View Reference

Component Connector End Views (Connector 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

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


Circuit/System Testing

1. Ignition ON, turn signals OFF.
2. Observe the right front turn signal. The turn signal should not be illuminated.

• If the turn signal is illuminated, test the right turn signal lamps supply voltage circuit for a short to voltage.

3. Test the right turn signal lamps supply voltage circuit for a short to ground or an open/high resistance.
4. If all circuits test normal, replace the BCM.



Repair Instructions

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


Control Module References (Programming and Relearning) for replacement, setup and programming