Did you perform the Lighting Systems Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

1. Turn ON the ignition with the engine OFF.
2. Place the headlamp switch in the PARK LAMP position.

Do the park lamps illuminate?

Go to Step 3

Go to Park Lamps Inoperative

1. Place the headlamp switch in the ON position.
2. Place the headlamp dimmer switch in the HIGH BEAM position.

Do the high beam headlamps illuminate?

Go to Step 4

Go to Headlamps Inoperative - High Beams

Place the headlamp dimmer switch in the LOW BEAM position.

Do the low beam headlamps illuminate?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 5

1. Install a scan tool.
2. Turn ON the ignition, with the engine OFF.
3. With the scan tool, command the HDLP LO BM relay ON and OFF.

Do hear a click when you command the HDLP LO BM relay ON and OFF?

Go to Step 8

Go to Step 6

1. Turn OFF the ignition.
2. Remove the HDLP LO BM relay.
3. Turn ON the ignition with the engine OFF.

Connect a test lamp between the controlled positive voltage circuit of the HDLP LO BM relay coil and a good ground.

Does the test lamp illuminate?

Go to Step 7

Go to Step 17

1. Connect a test lamp between the controlled positve voltage circuit and the control circuit of the HDLP LO BM relay coil.
2. With a scan tool, command the HDLP LO BM relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 12

Go to Step 11

1. Turn OFF the ignition.
2. Remove the HDLP LO BM relay.
3. Connect a test lamp between the battery positve voltage circuit of the HDLP LO BM relay switch and a good ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 15

Connect a 20 amp fused jumper between the battery positve voltage circuit of the HDLP LO BM relay switch and the supply voltage circuit of the low beam headlamps.

Do the low beam headlamps illuminate?

Go to Step 12

Go to Step 10

1. Disconnect the harness connector of the low beam headlamp.
2. Connect a test lamp between the supply voltage circuit of the low beam headlamp and a good ground.

Does the test lamp illuminate?

Go to Step 16

Go to Step 14

Test for an open or high resistance in the control circuit of the HDLP LO BM relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 13

Inspect for poor connections at the HDLP LO BM relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 19

Inspect for poor connections at the headlamp dimmer switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 20

Go to Step 18

Repair an open or high resistance in the the supply voltage circuit of the low beam headlamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 20

--

Repair an open or high resistance in the battery positive voltage circuit of the HDLP LO BM relay switch. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 20

--

Repair an open or high resistance in the ground circuit of the low beam headlamps. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 20

--

Repair an open or high resistance in the controlled positive voltage circuit of the HDLP LO BM relay coil. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 20

--

Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal, and Hazard Switch Replacement - On Vehicle in Steering Wheel and Column-Tilt.

Did you complete the replacement?

Go to Step 20

--

Replace the HDLP LO BM relay.

Did you complete the replacement?

Go to Step 20

--

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 4