GM Service Manual Online
For 1990-2009 cars only

Exterior Lights Diagnostic System Check

Step

Action

Normal Result(s)

Abnormal Result(s)*

1

  1. Turn the headlamp switch to the PARK position.
  2. Turn the headlamp switch to the OFF position.

Front park lamps, rear side marker, rear tail lamps, and license plate lamps are illuminated.

    • All Park Lamps Inoperative.
    • All Rear Park Lamps Inoperative.

2

  1. Turn the ignition switch to the ON position.
  2. Cover the DRL ambient light sensor with a dark cloth (Canada only).
  1. Front turn signal lamps illuminate for daytime running lamps (Domestic/Export).
  2. The low beam headlamps are ON (Canada only).
  3. Park, turn, and marker lamps illuminate with ambient light sensor covered (Canada only).
    • Daytime Running Lamps (DRL) Inoperative (Domestic/Export).
    • Daytime Running Lamps (DRL) Inoperative (Canada).

3

  1. Move the turn signal lever into the LH turn position.
  2. Move the turn signal lever into the RH turn position.
  3. Return the turn signal lever to the OFF position.

The LH or RH turn signal lamps flash ON and OFF.

    • Turn Signal Lamp On One Side Inoperative.
    • Both Turn Signal Lamps Inop/Hazard Lamps Work.

4

  1. Move the hazard warning switch to the ON position.
  2. Move the hazard warning switch to the OFF position.

The front and rear turn signal lamps flash ON and OFF.

Hazard Lamps Inoperative/Turn Lamps Work.

5

  1. Depress the brake pedal.
  2. Release the brake pedal.
  1. The center high mounted stop lamp (CHMSL) and rear stop lamps are illuminated.
  2. The center high mounted stop lamp (CHMSL) and rear stop lamps turn OFF.
    • All Stop Lamps Inoperative (Dom. and Can.).
    • All Stop Lamps Inoperative (Export).
    • Stoplamps Inoperative/CHMSL Works (Dom. and Can.).
    • Center High Mount Stop Lamp Inoperative (Dom/Can)

* Refer to the appropriate symptom diagnostic table for the applicable abnormal result.