For 1990-2009 cars

### 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.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Left Turn Indicator Supply Voltage | B0525 00 | 1 | 1 | --
Right Turn Indicator Supply Voltage | B0530 00 | 1 | 1 | --
Turn Signal/Multifunction Switch Signal | 2 | 2 | 2 | --
Left Turn Signal Control | B0532 00 | B0534 00 | B0533 00 | --
Right Turn Signal Control | B0527 00 | B0529 00 | B0528 00 | --
Front Park/Turn Signal Lamps Ground | -- | 1 | -- | --
Rear Park/Turn Signal Lamp Ground | -- | 1 | -- | --
Turn Signal/Multifunction Switch Ground | -- | 2 | -- | --

1. Turn Signal Malfunction
2. Turn Signal Switch Malfunction

### Circuit/System Description

Ground is applied at all times at G106 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. When a turn signal request is received by the BCM, a serial data message is sent to the instrument panel cluster (IPC) requesting the respective turn signal indicator be pulsed ON and OFF.

### Reference Information

#### Schematic Reference

Exterior Lights Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Exterior Lighting Systems Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Ignition ON, command the following ON and OFF with a scan tool. The appropriate turn signal lamp should turn ON and OFF.

• | LF Turn Signal

• | LR Turn Signal

• | RF Turn Signal

• | RR Turn Signal

⇒ | If the turn signal lamp is always ON or does not turn ON, refer to Turn Signal Lamp Malfunction.

2. Ignition ON, operate the left and right turn signals from the turn signal/multifunction switch and verify the left and right turn signal lamps and indicators operate normal.

⇒ | If the left or right turn signals do not operate, refer to the Turn Signal Switch Malfunction.

### Circuit/System Testing

#### Turn Signal Switch Malfunction

1. Ignition OFF, disconnect the harness connector X204 at the turn signal/multifunction switch.
2. Test for less than 5 ohms between the ground circuit terminal B9 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify B+ is present between the turn signal switch signal circuit terminal B5 and ground.

⇒ | If not the specified value, test the signal circuit terminal B5 for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

4. If all circuits test normal, test or replace the turn signal/multifunction switch.

#### Turn Signal Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the inoperative turn signal lamp.
2. Test for less than 5 ohms between the ground circuit terminal G and ground.

⇒ | If more than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal A and ground.
4. Ignition ON, command the inoperative lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF.

⇒ | 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.

5. If all circuits test normal, test or replace the inoperative bulb.

#### Turn Signal Indicators Malfunction

Ignition ON, with a scan tool perform the Display Test for the instrument panel cluster (IPC) and observe the turn signal lamp indicators.

⇒ | If the turn signal lamp indicators illuminate during the test, replace the BCM.

⇒ | If the turn signal lamp indicators do not illuminate during the test or remain illuminated at all times, replace the IPC.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Park/Turn Signal/Side Marker Lamp Bulb Replacement

• | Tail Lamp Bulb Replacement

• | Turn Signal Multifunction Switch Replacement

• | Control Module References for BCM replacement, setup, and programming