GM Service Manual Online
For 1990-2009 cars only

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Action

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Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics

Connector End View Reference: Lighting Systems Connector End Views or Steering Wheel and Column Connector End Views in Steering Wheel and Column

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

  1. Turn ON the ignition, with the engine OFF.
  2. Place the headlamp switch in the HEADLAMP position.
  3. Place the headlamp dimmer switch in the LOW BEAM position.

Do the low beam headlamps illuminate?

Go to Step 3

Go to Headlamps Inoperative - Low Beams

3

Place the headlamp dimmer switch in the HIGH BEAM position.

Do the high beam headlamps illuminate?

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

Go to Step 4

4

Are both high beam headlamps inoperative?

Go to Step 7

Go to Step 5

5

  1. Disconnect the inoperative high beam headlamp.
  2. Connect a test lamp between the supply voltage circuit of the inoperative high beam headlamp and a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 17

6

Connect a test lamp between the supply voltage circuit of the inoperative high beam headlamp and the ground circuit of the inoperative high beam headlamp.

Does the test lamp illuminate?

Go to Step 16

Go to Step 19

7

Command the HDLP HI BM relay ON and OFF by cycling the headlamp dimmer switch between the LOW BEAM and the HIGH BEAM position.

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

Go to Step 10

Go to Step 8

8

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

Connect a test lamp between the supply voltage circuit of the HDLP HI BM relay coil and a good ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 20

9

  1. Connect a test lamp between the supply voltage circuit of the HDLP HI BM relay coil and the control circuit of the HDLP HI BM relay.
  2. With the headlamp dimmer switch, command the HDLP HI BM relay ON and OFF.

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

Go to Step 14

Go to Step 12

10

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

Does the test lamp illuminate?

Go to Step 11

Go to Step 18

11

Connect a 10-amp fused jumper between the battery positive voltage circuit of the HDLP HI BM relay switch and the supply voltage circuit of the high beam headlamps.

Do the high beam headlamps illuminate?

Go to Step 14

Go to Step 13

12

Test for an open or short to battery positive voltage in the control circuit of the HDLP HI BM relay. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 15

13

Test for an open or high resistance in the supply voltage circuit of the high beam headlamps. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 19

14

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

Did you find and correct the condition?

Go to Step 24

Go to Step 22

15

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

Did you find and correct the condition?

Go to Step 24

Go to Step 21

16

Inspect for poor connections at the inoperative high beam headlamp. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 23

17

Repair an open or short to ground in the supply voltage circuit of the appropriate high beam headlamp. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 24

--

18

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

Did you complete the repair?

Go to Step 24

--

19

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

Did you complete the repair?

Go to Step 24

--

20

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

Did you complete the repair?

Go to Step 24

--

21

Replace the headlamp dimmer switch. Refer to Turn Signal Multifunction Switch Replacement in Steering Wheel and Column.

Did you complete the replacement?

Go to Step 24

--

22

Replace the HDLP HI BM relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 24

--

23

Replace the inoperative high beam headlamp. Refer to Headlamp Bulb Replacement .

Did you complete the replacement?

Go to Step 24

--

24

Operate the system in order to verify the repair.

Did you correct the condition?

System OK

Go to Step 2