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

DEFINITION: One of the following lamp(s) are always on: daytime running lamps, low beam headlamps, RH high beam headlamp, or high beam headlamps.

1

Did you perform the Lighting System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

  1. Turn the headlamp switch to the OFF position.
  2. Turn the ignition switch to the OFF position.
  3. Observe the daytime running lamps.

Are the daytime running lamps illuminated?

Go to Step 3

Go to Step 4

3

Disconnect the daytime running lamp relay K131.

Are the daytime running lamps illuminated?

Go to Step 14

Go to Step 15

4

  1. With the headlamp switch in the OFF position.
  2. Place the ignition switch in the ON position.
  3. Observe the low beam headlamps.

Are the low beam headlamps illuminated?

Go to Step 5

Go to Step 6

5

Disconnect the low beam relay K131.

Are the are the low beam headlamps illuminated?

Go to Step 12

Go to Step 9

6

  1. With the headlamp switch in the OFF position.
  2. Place the ignition switch in the OFF position.
  3. Observe the RH high beam headlamp.

Is the RH high beam headlamp illuminated?

Go to Step 7

Go to Step 8

7

Disconnect the RH headlamp relay.

Is the RH high beam headlamp illuminated?

Go to Step 13

Go to Step 17

8

  1. Turn the ignition switch to the ON position.
  2. Turn the headlamp switch to the HEAD position.
  3. Insure that the high beam switch is in the OFF position.
  4. Observe the high beam headlamps.

Are both the high beam headlamps illuminated?

Go to Step 11

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

9

  1. With the headlamp switch in the OFF position.
  2. Disconnect the BCM connector C2.
  3. Probe the low beam ON/OFF circuit of the BCM with a test lamp that is connected to B+.

Does the test lamp illuminate?

Go to Step 10

Go to Step 16

10

Test for a short to ground in the low beam ON/OFF circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 18

11

Test for a short to B+ in the high beam ON/OFF circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

Go to Step 19

12

Locate a short to B+ in the low beam supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

--

13

Locate a short to B+ in the RH headlamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

--

14

Locate a short to B+ in the DRL supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 20

--

15

Replace the daytime running lamp relay K131.

Is the replacement complete?

Go to Step 20

--

16

Replace the low beam relay K131.

Is the replacement complete?

Go to Step 20

--

17

Replace the RH headlamp relay.

Is the replacement complete?

Go to Step 20

--

18

Replace the headlamp switch. Refer to Headlamp Switch Replacement .

Is the replacement complete?

Go to Step 20

--

19

Replace the high beam switch. Refer to Turn Signal Switch Replacement - On Vehicle in Steering Wheel and Column - Tilt.

Is the replacement complete?

Go to Step 17

--

20

  1. Connect all connectors and components that were disconnected.
  2. Verify that the headlamps operate properly.

Do the headlamps operate properly?

System OK

Go to Step 2