Voltage runs through the left and right turn signal fuses of the instrument panel I/P fuse block, 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.

Schematic Reference

Electrical Information Reference

Scan Tool Reference

Ignition ON, observe right or left turn signal while engaging the turn signal multifunction switch in the appropriate position. The selected bulbs should illuminate.

Turn Signal Multifunction Switch Circuit Testing

1. Ignition OFF, disconnect the harness connector at the turn signal multifunction switch.
2. Ignition ON, install a test lamp between the turn signal voltage supply circuit and ground. The test lamp should flash ON and OFF.

⇒	If the test lamp does not flash, test the voltage supply circuit for a short to ground or an open/high resistance.

3. Install a 3-amp fused jumper wire between the voltage supply circuit and the turn signal circuit. Verify that the proper turn signal lamps are ON.

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

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

Park/Turn Signal/Turn Signal Indicator Circuit Testing

1. Ignition OFF, remove the inoperative light bulb.
2. Test for less than 1.0 ohm of resistance between the ground circuit and ground.

⇒	If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit and the ground circuit.
4. Ignition ON, turn ON the appropriate turn signal, the test lamp should flash.

⇒	If the test lamp remains ON all the time, test for a short to voltage on the control circuit . If the circuit tests normal, test or replace the BCM.

⇒	If the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the control circuit. If the circuit tests normal, test or replace the turn signal multifunction switch.

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

Instrument Panel (I/P) Circuit Testing

1. Ignition OFF, disconnect the harness connector at the I/P.
2. Test for less than 1.0 ohm of resistance between the ground circuit and ground.

⇒	If greater than 1.0 ohm, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit and the ground circuit.
4. Ignition ON, turn ON the appropriate turn signal. The test lamp should flash.

⇒	If the test lamp remains ON all the time, test for a short to voltage on the control circuit. If the circuit tests normal, test or replace the BCM.

⇒	If the test lamp remains OFF all the time, test for a short to ground or an open/high resistance on the control circuit. If the circuit tests normal, test or replace the turn signal multifunction switch.

5. If all circuits test normal, replace the I/P.

Turn Signal Switch Testing

1. Ignition OFF, disconnect the harness connector at the turn signal multifunction switch.
2. Test for infinite resistance between the signal terminals C2 pins G and H and the voltage supply terminal C1 pin 3 with the turn signal multifunction 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 terminals C2 pins G and H and the voltage supply terminal C1 pin 3 with the switch in the closed position.

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

Park/Turn Signal/Turn Signal Indicator Bulb Testing

1. Ignition OFF, remove the appropriate light bulb.
2. Test for less than 4.5 ohms between the two terminals 1 and 2 on the light bulb.

⇒	If greater than 4.5 ohms, replace the light bulb.

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