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
--- | --- | --- | --- | ---
Turn Signal Ground Circuit | -- | -- | 1 | --
Turn Signal Switch | 1 | -- | 1 | --
1. Turn Signal Lamps and/or Indicators Always On or Flashing

### Circuit/System Description

Voltage runs through the left and right turn signal fuses of the instrument panel I/P fuseblock, then through the body control module BCM, before reaching the turn signal multifunction switch. When the turn signal switch is engaged, the switch closes and supplies voltage to the front and rear park/turn signal lamps.

### Diagnostic Aids

• | There are certain relays that are PCB or soldered to the underhood fuseblock circuit board and any relay replacement would warrant a replacement of the underhood fuseblock.

• | This vehicle is not equipped with a turn signal relay.

• | An open/high resistance or a short to ground in the turn signal multifunction switch would cause the turn signal lamps to always be ON or continually flashing.

### Reference Information

#### Schematic Reference

Exterior Lights Schematics

#### Connector End View Reference

Displays and Gages Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

• | Scan Tool Data Definitions

• | Scan Tool Data List

• | Scan Tool Output Controls

### Circuit/System Verification

Ignition ON, observe the right or left turn signal while engaging the turn signal multifunction switch in the appropriate position.

### Circuit/System Testing

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

⇒ | If greater than 5 ohms, test the ground circuit for an open/high resistance.

3. Install a 3-amp fused jumper wire between the signal circuit and ground. Verify that the proper turn signal lamp is ON.

⇒ | If the turn signals are not ON, test the left and right signal circuit of the turn signal multifunction switch for a short to voltage or an open/high resistance.

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

### Component Testing

1. Ignition OFF, disconnect the harness connector at the turn signal multifunction switch.
2. Test for infinite resistance between the signal terminal and the voltage supply terminal with the switch in the open position.

⇒ | If less than infinite resistance, replace the turn signal multifunction switch.

3. Test for less than 1.5 ohms between the signal terminal and the voltage supply terminal with the switch in the closed position.

⇒ | If greater than 1.5 ohms, replace the turn signal multifunction switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Hazard Warning Switch Replacement

• | Turn Signal Multifunction Switch Replacement