Diagnostic Aids

WARNING: This page is about a different car, the 2007 Pontiac G5 Pursuit, 2007 Pontiac G5, and 2007 Chevrolet Cobalt. However, it is still accessible from the selected car via links, so may be relevant.

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.
If the DTC is a history DTC, the problem may be intermittent. Perform the tests shown while moving related wiring and connectors. This can often cause the malfunction to occur. Refer to Testing for Intermittent Conditions and Poor Connections .

DTC B3948

Step	Action	Yes	No
Schematic Reference: Exterior Lights Schematics
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to DIAGNOSTIC SYSTEM CHECK - VEHICLE
2	Turn ON the ignition, with the engine OFF. Place the turn signal switch in the left turn position. Does the left front turn signal operate properly?	Go to Testing for Intermittent Conditions and Poor Connections	Go to Step 3
3	Observe the left front turn signal lamp. Is the lamp always ON?	Go to Step 6	Go to Step 4
4	Inspect the condition of the left front turn signal bulb. Is the bulb burned out?	Go to Step 8	Go to Step 5
5	Test for the following in the left turn signal lamp supply voltage circuit: An open A high resistance A short to ground Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 10	Go to Step 7
6	Test for a short to voltage in the left turn signal lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 10	Go to Step 7
7	Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 10	Go to Step 9
8	Replace the left front turn signal bulb. Refer to Headlamp Bulb Replacement . Did you complete the replacement?	Go to Step 10	-
9	Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement?	Go to Step 10	-
10	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Setting the DTC, as specified in the supporting text. Does the DTC reset?	Go to Step 2	System OK