GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2004 🢒 Grand Prix 🢒 DTC 🢒 DTC B3951

Circuit Description

Ground is applied to the turn signal switch. When the turn signal switch is placed in the turn right position, ground is applied to the body control module (BCM) through the right turn signal switch circuit. The BCM applies a pulsating voltage to the RF and RR turn signal lamps through the RF and RR turn signal voltage supply circuits.

Conditions for Running the DTC

The battery voltage must be between 9.0-16 volts.

Conditions for Setting the DTC

A short to ground or an open in the RR turn signal voltage supply circuit is present for longer then 0.1 seconds.

Action Taken When the DTC Sets

The right rear turn signal lamp does not work.

Conditions for Clearing the DTC
    • The DTC will clear on current status after the condition for setting the fault is corrected.
    • DTC B3951 will set a history code which will clear after 100 consecutive ignition cycles without a fault present.
    • History and current DTCs can be cleared using a scan tool.

Diagnostic Aids
    • Check the RR turn lamp bulb. If the bulb is open, DTC B3950 will be set.
    • If the DTC is a history DTC, the fault may be interment. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
    • An interment short to ground or an open in the following locations may cause an intermittent malfunction to occur:
       - The BCM
       - The right rear turn signal supply voltage circuit

Step

Action

Yes

No

Schematic Reference: Exterior Lights Schematics

Connector End View Reference: Master Electrical Component List in Wiring Systems

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2
  1. Turn ON the ignition, with the engine OFF.
  2. Place the turn signal switch in the TURN RIGHT position.

Do the rear turn signal lamps flash on and off?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the RR tail lamp assembly.
  3. Connect a test lamp between battery positive voltage and the RR turn signal voltage supply circuit at the BCM harness connector C2.

Does the test lamp illuminate?

Go to Step 6

Go to Step 4

4
  1. Disconnect the BCM harness connector C3.
  2. Test for continuity in the RR turn signal voltage supply circuit between the BCM harness connector C3 and the RH tail lamp assembly. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 8

Go to Step 5

5

Inspect for a high resistance or an open 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 8

Go to Step 7

6

Repair a short to ground in the RR turn signal voltage supply circuit. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 8

--

7

Important: After replacing the BCM, perform the setup procedure. Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control System.

Replace the BCM. Refer to Body Control Module Replacement in Body Control System.

Did you complete the replacement?

Go to Step 8

--

8
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

Go to Step 2

System OK