The low beam headlamps are operated when the driver places the headlamp switch in the HEADLAMP position and the dimmer switch is placed in the LOW BEAM. The LT HDLP and RT HDLP fuse in the IP fuse block supply battery positive voltage to the headlamps. The low beam control circuits continue to the headlamp switch. With the headlamp switch on and the dimmer in the low beam position, a ground path for the lamps is provided. The low beam control circuit also provides the body control module (BCM) with a reference voltage indicating when the low beam lamps are ON.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Lighting Systems Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Place the headlamp switch in the ON position and the place dimmer switch in the LOW position. Verify the low beam headlamps are illuminated.

1. Ignition OFF, disconnect the harness connector C1 at the turn signal/multifunction switch.
2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal E and ground.

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

3. Connect the harness connector C1 at the turn signal/multifunction switch.
4. Disconnect the harness connector C2 at the body control module (BCM).
5. Connect a test lamp between the signal circuit terminal B6 and B+.
6. Turn the headlamps ON and OFF with the dimmer switch in the LOW position. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, test or replace the turn signal/multifunction switch.

⇒	If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the turn signal/multifunction switch.

7. Connect the harness connector C2 at the BCM.
8. Disconnect the harness connector at the affected headlamp.
9. Verify a test lamp illuminates between the B+ circuit terminal A and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

10. Connect a test lamp between the control circuit terminal B and B+.
11. Turn the headlamps ON and OFF with the dimmer switch in the LOW position. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, test or replace the turn signal/multifunction switch.

⇒	If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the turn signal/multifunction switch.

12. Connect the harness connector at the affected headlamp.
13. With the headlamps OFF, verify the scan tool Low Beam Feedback parameter is greater than 11 volts.

⇒	If less than the specified value, replace the BCM.

14. With headlamps ON and the dimmer switch in the LOW position, verify the scan tool Low Beam Feedback parameter is less than 2 volts.

⇒	If greater than the specified value, replace the BCM.

15. If all circuits test normal, replace the affected headlamp bulb.

1. Ignition OFF, disconnect the harness connector C1 at the turn signal/multifunction switch.
2. Test for infinite resistance between the control circuit terminal C and the following circuits:

•	Ground circuit terminal E

•	Ground circuit terminal A

⇒	If less than the specified value, replace the turn signal/multifunction switch.

3. With the switch in the ON position and the dimmer in the HIGH position, test for less than 2.0 ohms between the control circuit terminal C and the ground circuit terminal E.

⇒	If greater than the specified value, replace the turn signal/multifunction switch.

Turn Signal Multifunction Switch Replacement