Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC B3948 02 : Left Front Turn Signal Circuit Short to GroundDTC B3948 05 : Left Front Turn Signal Circuit Open or Short to Voltage
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Hazard Switch Signal | 1 | 3 | 3 | -- |
Left Front Turn Signal Lamp Supply Voltage | B3948 02 | B3948 05 | B3948 05 | -- |
Right Front Turn Signal Lamp Supply Voltage | B3949 02 | B3949 05 | B3949 05 | -- |
Left Rear Stop/Turn Signal Lamp Supply Voltage | B3950 02 | B3950 05 | B3950 05 | -- |
Right Rear Stop/Turn Signal Lamp Supply Voltage | B3951 02 | B3951 05 | B3951 05 | -- |
Left Turn Signal Switch Signal | 1 | 2 | -- | -- |
Right Turn Signal Switch Signal | 1 | 2 | -- | -- |
Left Rear Stop/Turn Lamp Ground | -- | 2 | 2 | -- |
Right Rear Stop/Turn Lamp Ground | -- | 2 | 2 | -- |
Turn Signal/Multifunction Switch Ground | -- | 2 | 2 | -- |
Turn Signal Lamp - LF Ground | -- | 2 | 2 | -- |
Turn Signal Lamp - RF Ground | -- | 2 | 2 | -- |
1. Turn Signal Lamps and/or Indicators Always On or Flashing. 2. Turn Signal Lamps and/or Indicators Inoperative. 3. Hazard Lamps Inoperative. | ||||
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
B3948 02
This DTC will set when the BCM detects a short to ground in the left front turn signal lamp supply voltage circuit.
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.
Reference Information
Schematic Reference
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
B3948 02
- Ignition OFF, disconnect the BCM C1 harness connector.
- Remove the left front turn signal bulb.
- 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 all circuit test normal, replace the BCM.
| ⇒ | If the test lamp illuminates, repair the left front turn signal lamp supply voltage circuit for a short to ground. |
B3948 05
- Ignition OFF, disconnect the BCM C1 harness connector.
- 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.
- Connect the BCM C1 harness connector.
- Disconnect the left front turn signal lamp harness connector.
- Ignition ON, turn on the left turn signal.
- Verify that a test lamp illuminates between the left front turn signal lamp supply voltage circuit and ground.
- If all circuit test normal, replace the BCM.
| ⇒ | If the test lamp illuminates, repair the left front turn signal lamp supply voltage circuit for a short to voltage. |
| ⇒ | If the test lamp does not illuminate, repair the left front turn signal lamp supply voltage circuit for an open/high resistance. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
