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
DTC B3949 02: Right Front Turn Signal Circuit Short to Ground
DTC B3949 05: Right 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 | 2 | 2 | 2 | -- |
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 Turn Lamp Supply Voltage | B3950 02 | B3950 05 | B3950 05 | -- |
Right Rear Turn Lamp Supply Voltage | B3951 02 | B3951 05 | B3951 05 | -- |
Left Turn Signal Switch Signal | 1 | 1 | -- | -- |
Hazard Switch Ground | -- | 2 | 2 | -- |
Right Turn Signal Switch Signal | 1 | 1 | -- | -- |
Left Rear Stop/Turn Lamp Ground | -- | 1 | 1 | -- |
Right Rear Stop/Turn Lamp Ground | -- | 1 | 1 | -- |
Turn Signal/Multifunction Switch Ground | -- | 1 | 1 | -- |
Turn Signal Lamp - LF Ground | -- | 1 | 1 | -- |
Turn Signal Lamp - RF Ground | -- | 1 | 1 | -- |
1. Turn Signal Lamps and/or Indicators Malfunction. 2. Hazard Lamps Malfunction | ||||
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. The BCM then applies a pulsating voltage to the front and rear turn signal lamps through there respective voltage supply circuits. Ground for the left front turn signal lamp is supplied at G101. Ground for the right front turn signal lamp is supplied at G102. For more detailed information concerning turn signal lamp operation refer to Exterior Lighting Systems Description and Operation .
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 LF turn signal voltage supply circuit.
B3948 05
This DTC will set when the BCM detects an open or short to voltage in the LF turn signal voltage supply circuit.
B3949 02
This DTC will set when the BCM detects a short to ground in the RF turn signal voltage supply circuit.
B3949 05
This DTC will set when the BCM detects an open or short to voltage in the RF turn signal voltage supply circuit.
Actions 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. |
| • | When DTC B3949 02 is present, the RF turn signal lamp will not operate. |
| • | When DTC B3949 05 is present, the RF turn signal lamp will be ON at all times for a short to voltage condition. For an open condition, the RF 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. |
| • | Check the RF turn signal bulb. If the bulb is open, DTC B3949 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
- Ignition OFF, disconnect the harness connector at the appropriate turn signal lamp.
- Test for less than 1.0 ohm of resistance between the ground circuit terminal G and ground.
- Connect a test lamp between the control circuit terminal A and the ground circuit terminal G.
- Command the appropriate turn signal lamp ON and OFF with the turn signal/multifunction switch. The test lamp should turn ON and OFF as the switch is cycled between the commanded states.
- If all circuits test normal, test or replace the appropriate turn signal lamp assembly.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BCM replacement, setup, and programming
