B3948

DTC B3948

DTC DESCRIPTOR

DTC B3948 02
Left Front Turn Signal Circuit Short to Ground

DTC B3948 05
Left Front Turn Signal Circuit Open or Short to Voltage




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
Ground is applied at all times at G201 to the turn signal/multifunction switch. The turn signal lamps may only be activated with the ignition switch in the ON or START position. When the turn signal/multifunction switch is placed in either the TURN RIGHT or TURN LEFT position, ground is applied to the body control module (BCM) through either the right turn or left turn signal switch signal circuit. Battery voltage is applied at all times from the BATT MAIN 3 fuse to the BCM. The BCM then applies a pulsating voltage to the front and rear turn signal lamps. Ground for the left front turn signal lamp is supplied at G101. Ground for the right front turn signal lamp is supplied at G102. Ground for the left rear turn signal lamp is supplied at G400. Ground for the right rear turn signal lamp is supplied at G402.

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

CONDITIONS FOR SETTING THE DTC

DTC B3948 02
This DTC will set when the BCM detects a short to ground in the left front turn signal lamp supply voltage circuit.

DTC B3948 05
This DTC will set when the BCM detects an open or short to voltage in the left front turn signal lamp supply voltage circuit.

ACTION TAKEN WHEN THE DTC SETS
- When DTC B3948 02 is present, the LF turn signal lamp will not operate.
- When DTC B3948 05 is present, the LF turn signal lamp will be ON at all times for a short to voltage condition. For an open condition, the LF turn signal lamp will be inoperative.

CONDITIONS FOR CLEARING THE DTC
- The condition responsible for setting the DTC no longer exists.
- You issue a scan tool CLEAR DTCs command.
- A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

DIAGNOSTIC AIDS
Check the LF turn signal bulb. If the bulb is open, DTC B3948 05 will set as current only.

CIRCUIT/SYSTEM TESTING

DTC B3948 02
1. Ignition OFF, disconnect the BCM C1 harness connector.
2. Remove the left front turn signal bulb.
3. Verify that a test lamp does not illuminate between battery voltage and the left front turn signal lamp supply voltage circuit at the BCM C1 harness connector.
- If the test lamp illuminates, repair the left front turn signal lamp supply voltage circuit for a short to ground.
4. If all circuit test normal, replace the BCM.

DTC B3948 05
1. Ignition OFF, disconnect the BCM C1 harness connector.
2. Verify that a test lamp does not illuminate between ground and the left front turn signal lamp supply voltage circuit at the BCM C1 harness connector.
- If the test lamp illuminates, repair the left front turn signal lamp supply voltage circuit for a short to voltage.
3. Connect the BCM C1 harness connector.
4. Disconnect the left front turn signal lamp harness connector.
5. Ignition ON, turn on the left turn signal.
6. Verify that a test lamp illuminates between the left front turn signal lamp supply voltage circuit and ground.
- If the test lamp does not illuminate, repair the left front turn signal lamp supply voltage circuit for an open/high resistance.
7. If all circuit test normal, replace the BCM.

REPAIR INSTRUCTION

IMPORTANT:Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

- Underhood Electrical Center or Junction Block Replacement
- Control Module References for BCM replacement, setup, and programming