Battery voltage is supplied at all times to the headlamp switch from the HDLP fuse located in the underhood fuse block. When the switch is in the headlamps ON position, battery voltage is applied through the headlamp switch signal circuit, routed through the headlamp dimmer switch, and the headlamp supply voltage circuit illuminating the low beam headlamps. With the dimmer switch in the high beam position, battery voltage is also routed through the headlamp high beam supply voltage circuit illuminating the high beam headlamps. At the same time battery voltage is applied to the instrument panel cluster (IPC) illuminating the headlamp high beam indicator. Ground for the left and right headlamps is provided at G203.

Schematic Reference

Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Exterior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, turn ON and observe the low beam headlamps. The low beam headlamps should illuminate.

⇒	If the low beam headlamps do not illuminate, refer to the appropriate circuit test listed below.

•	Low Beam Headlamps Circuit Test (+DRL)

•	Low Beam Headlamps Circuit Test (-DRL)

2. Turn ON the headlamps and cycle the dimmer switch between high and low beams. The high beam headlamps and the IPC high beam indicator should turn ON and OFF when changing between the commanded states.

⇒	If the high beam headlamps do not turn ON and OFF as specified, refer to High Beam Headlamp Circuit Test.

⇒	If the high beam headlamps illuminate, but the IPC high beam headlamp indicator does not illuminate, refer to High Beam Headlamp Indicator Malfunction.

Low Beam Headlamps Circuit Test (+DRL)

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground.

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

3. Ignition OFF, connect the harness connector at the headlamp switch and disconnect the X201 inline harness connector.
4. Connect a test lamp between the control circuit terminal E13 and ground.
5. Ignition ON, cycle the headlamp switch ON and OFF. 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 voltage. If the circuit tests normal, test or replace the headlamp switch.

⇒	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, test or replace the headlamp switch.

6. Ignition OFF, headlamp switch OFF, connect the X201 inline harness connector and disconnect the DRL relay.
7. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal H30 and ground.

⇒	If the test lamp illuminates, test the control circuit for a short to voltage.

8. Connect a test lamp between the control circuit terminal H87A and ground.
9. Ignition ON, headlamps ON with the dimmer switch between the low beam position. The test lamp should illuminate in the low position.

⇒	If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit test normal, test or replace the headlamp turn signal multifunction switch.

10. Disconnect the harness connector at the inoperative low beam headlamp.
11. Test for less than 1.0 ohm between the ground circuit terminal C and ground.

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

12. Connect the harness connector at the low beam headlamp.
13. Headlamps ON, install a 10A fused jumper wire between the control circuit terminal H87A and the control circuit terminal H30. The low beam headlamps should illuminate.

⇒	If the low beam headlamps do not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the low headlamp.

14. If all circuits test normal, test or replace the DRL relay.

Low Beam Headlamps Circuit Test (-DRL)

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground.

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

3. Ignition OFF, connect the harness connector at the headlamp switch and disconnect the X201 inline harness connector.
4. Connect a test lamp between the control circuit terminal E13 and ground.
5. Ignition ON, cycle the headlamp switch ON and OFF. 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 voltage. If the circuit tests normal, test or replace the headlamp switch.

⇒	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, test or replace the headlamp switch.

6. Ignition OFF, headlamp switch OFF, connect the X201 inline harness connector and disconnect the harness connector at the inoperative low beam headlamp.
7. Test for less than 1.0 ohm between the ground circuit terminal C and ground.

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

8. Connect a test lamp between the control circuit terminal A and ground.
9. Ignition ON, cycle the headlamp switch ON and OFF. 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 voltage.

⇒	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, test or replace the turn signal multifunction switch.

10. If all circuits test normal, test or replace the inoperative low beam headlamp.

High Beam Headlamp Circuit Test

1. Ignition OFF, disconnect the harness connector at the inoperative high beam headlamp.
2. Test for less than 5.0 ohms between the appropriate ground circuit terminal listed below and ground.

•	Terminal C (-V22)

•	Terminal B (+V22)

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

3. Connect a test lamp between the appropriate control circuit terminal listed below and ground.

•	Terminal B (-V22)

•	Terminal A (+V22)

4. Ignition ON, headlamps ON, cycle the headlamp dimmer switch ON and OFF. 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 voltage. If the circuit tests normal, test or replace the turn signal multifunction switch.

⇒	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, test or replace the turn signal multifunction switch.

5. If all circuits test normal, test or replace the inoperative high beam headlamp.

High Beam Headlamp Indicator Malfunction

1. Ignition OFF, disconnect the harness connector at the instrument panel cluster (IPC).
2. Ignition ON, high beam headlamps ON, verify that a test lamp illuminates between control circuit terminal A11 and ground.

⇒	If the test lamp does not illuminate, test the control circuit for an open/high resistance.

3. If the circuit tests normal, replace the IPC.

Headlamp Switch

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Test for infinite resistance between the control terminal G and the B+ terminal C with the switch in the OFF position.

⇒	If not the specified value, replace the headlamp switch.

3. Test for less than 2.0 ohms between the control terminal G and the B+ terminal C with the switch in the Headlamps ON position.

⇒	If greater than the specified value, replace the headlamp switch.

Turn Signal Multifunction Switch

1. Ignition OFF, disconnect the X201 inline harness connector at the turn signal/multifunction switch.
2. Test for infinite resistance between the control terminal E13 and the control terminal E11 with the dimmer switch in the low beam position.

⇒	If not the specified value, replace the turn signal/multifunction switch.

3. Test for less than 2.0 ohms between the control terminal E13 and the control terminal E11 with the dimmer switch in the high beam position.

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

4. Test for less than 2.0 ohms between the control terminal E13 and the control terminal E12 with the dimmer switch in the low beam position.

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

Relay Test

1. Ignition OFF, disconnect the DRL relay.
2. Test for 70-100 ohms between terminals H85 and H86.

⇒	If the resistance is not within the specified range, replace the appropriate relay.

3. Test for infinite resistance between the following terminals:

•	H30 and H86

•	H30 and H87

•	H30 and H85

•	H85 and H87

⇒	If not the specified value, replace the DRL relay.

4. Test for less than 5 ohms between terminals H30 and H87A.

⇒	If greater than the specified range, replace the DRL relay.

5. Install a 10A fused jumper wire between relay terminal H85 and 12 volts. Install a jumper wire between relay terminal H86 and ground. Test for less than 5 ohms between terminals H30 and H87.

⇒	If greater than the specified range, replace the DRL relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.