GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Did you perform the Lighting Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - Lighting Systems

2

Are both low beam lamps illuminated?

--

Go to Step 3

Go to Step 6

3

Remove the headlamp relay from the underhood fuse block.

Are the lamps still illuminated?

--

Go to Step 4

Go to Step 5

4

Locate and repair SHORT to voltage in CKT 1346 (LT BLU). IMPORTANT: WIRE IS LOCATED IN THE UNDERHOOD FUSE/RELAY CENTER.

Is the repair complete?

--

Go to Step 7

--

5

Replace the headlamp relay.

Is the repair complete?

--

Go to Step 7

--

6

Locate the SHORT to voltage according to it's respective fault:

    • RH LO BEAM ON - CKT 312 (TAN/WHT) between the underhood fuse block and RH headlamp.
    • LH LO BEAM ON - CKT 712 (YEL) between the underhood fuse block and LH headlamp.

Is the repair complete?

--

Go to Step 7

-

7

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2