GM Service Manual Online
For 1990-2009 cars only

Headlamps Do Not Switch Intensity Domestic

Step

Action

Value(s)

Yes

No

1

Was the Exterior Lights System Check performed?

--

Go to Step 2

Go to Exterior Lights System Check

2

Disconnect connector C200 at the steering column.

Do the headlamps remain lit?

--

Go to Step 4

Go to Step 3

3

Replace the headlamp dimmer switch.

Do the headlamps change in intensity after actuation of the headlamp dimmer switch?

--

Go to Exterior Lights System Check

Go to Step 4

4

Does the intensity of the headlamps lessen after actuation of the headlamp dimmer switch?

--

Go to Step 6

Go to Step 5

5

Repair the short to voltage in CKT 11 (LT GRN) between the following components:

    • The headlamp dimmer switch
    • The instrument cluster
    • The headlamps

Do the headlamps change in intensity after actuation of the headlamp dimmer switch?

--

Go to Exterior Lights System Check

Go to Step 6

6

Remove the daytime running lamp (DRL) relay from the instrument panel (IP) relay center.

Do the headlamps remain lit?

--

Go to Step 7

Go to Step 8

7

Repair the short to voltage in CKT 12 (TAN) between the IP relay center and S143.

Do the headlamps change in intensity after actuation of the headlamp dimmer switch?

--

Go to Exterior Lights System Check

Go to Step 8

8

Connect an unpowered test lamp between the IP relay center, cavity C2, and ground.

Does the test lamp light?

--

Go to Step 9

Go to Step 10

9

Repair the short to voltage in CKT 359 (PPL) between the IP relay center and steering column connector C200.

Do the headlamps change in intensity after actuation of the headlamp dimmer switch?

--

Go to Exterior Lights System Check

Go to Step 10

10

Replace the DRL relay.

Do the headlamps change in intensity after actuation of the headlamp dimmer switch?

--

Go to Exterior Lights System Check

--

Headlamps Do Not Switch Intensity Export

Step

Action

Value(s)

Yes

No

1

Was the Exterior Lights System Check performed?

--

Go to Step 2

Go to Exterior Lights System Check

2

Disconnect connector C200 at the steering column.

Do the high beam headlamps remain on?

--

Go to Step 6

Go to Step 3

3

Do the high beam headlamps turn off or remain off?

--

Go to Step 7

Go to Step 4

4

Do the low beam headlamps remain on?

--

Go to Step 8

Go to Step 5

5

Do the low beam headlamps turn off or remain off?

--

Go to Step 9

Go to Exterior Lights System Check

6

Locate and repair the short to voltage on CKT 11 (LT GRN) between the following components:

    • The headlamp dimmer switch
    • The instrument panel
    • The headlamps

Is the repair complete?

--

Go to Exterior Lights System Check

--

7

Replace the headlamp dimmer switch.

Is the repair complete?

--

Go to Exterior Lights System Check

--

8

Locate and repair the short to voltage on CKT 12 (TAN) between the following components:

    • The headlamp dimmer switch
    • The headlamps

Is the repair complete?

--

Go to Exterior Lights System Check

--

9

Replace the headlamp dimmer switch.

Is the repair complete?

--

Go to Exterior Lights System Check

--