GM Service Manual Online
For 1990-2009 cars only

Fuses

R HDLP Fuse

Location: Underhood junction block

Type: 10A Minifuse

Feeds: Circuit 140A and 140B

If the following system is operating normally, the fuse is most likely good:

    • Right high beam
    • Right low beam

If the fuse is blown, determine the cause of the blown fuse and repair.

Replace the fuse as needed.

HAZARD Fuse

Location: Underhood junction block

Type: 10A Minifuse

Feeds: Circuit 1040A

If the following system is operating normally, the fuse is most likely good:

Hazard lamps

If the fuse is blown, determine the cause of the blown fuse and repair.

Replace the fuse as needed.

L HDLP Fuse

Location: Underhood junction block

Type: 10A Minifuse

Feeds: Circuits 40A and 40B

If the following system is operating normally, the fuse is most likely good:

    • Left high beam
    • Left low beam

If the fuse is blown, determine the cause of the blown fuse and repair.

Replace the fuse as needed.

Grounds

Before checking the ground circuit from the faulty component all the way to the ground stud, check the circuit from the splice pack to ground by testing some of the other subsystems grounded by the same splice pack. If the other subsystems function properly, it is most likely that the path from the splice pack to ground is good, or at least one of the paths is good with redundantly grounded splice packs.

I/P Splice Pack #1

Location: Taped to harness behind I/P cluster

The systems grounded by I/P Splice Pack #1 are grounded redundantly with I/P Splice Pack #2 at ground point location D, the I/P chassis ground. If one of the following systems is operating normally the ground circuit is most likely good.

    • I/P dimmer
    • Cruise control
    • Headlamp switch
    • Cigar lighter element

Check for OPENS/SHORTS.

Repair as needed.

I/P Splice Pack #2

Location: Taped to harness behind I/P cluster

The systems grounded by I/P Splice Pack #2 are grounded redundantly with I/P Splice Pack #1 at ground point location C, the chassis ground. If one of the following systems is operating normally the ground circuit is most likely good.

    • Fuel lever sensor
    • Park brake switch
    • Wiper motor
    • Radio

Check for OPENS/SHORTS.

Repair as needed.

Components (SC1/SL/SW)

Headlamp Switch

Refer to Lever Combination Switch (LCS) for testing.

Repair/replace as needed.

Park Brake Switch

Check the BRAKE telltale. It should light with the park brake ON. It should not be lit with the park brake OFF, under normal operating conditions.

Check for park brake switch resistance.

Switch Resistance: Open when the park brake is OFF. Less than one ohm when the park brake is ON.

DRL Relay

The Lock, Unlock and DRL relays are interchangeable only with each other.

Substitute another relay to see if the problem is fixed.

Repair/replace as needed.

Headlamp Bulbs

Visually inspect the high and low beam bulbs. Check resistance through the bulb.

Check for OPENS/SHORTS.

Repair/replace as needed.

Instrument Panel Cluster and DRL Logic

The DRL Logic is incorporated into the speedometer gage and is not separately replaceable.

With the key in the RUN position the following readings should appear when taking measurements at the pins of the instrument cluster harness connector, instrument cluster disconnected.