GM Service Manual Online
For 1990-2009 cars only
  1. Inspect the HAZ, TL-MKR, and PNL Circuit Breakers to determine if any are open. If any circuit breaker is open, Locate and Repair the cause of the overload, then Replace the Circuit Breaker.
  2. Inspect the ground G 102 to assure that it is clean and tight.
  3. If the Stoplamps and Hazard Flashers do not operate, inspect for a short to ground or and open circuit in the wiring between the IP Fuse Block and the Turn Signal Flasher.
  4. If a single lamp does not light, inspect the bulbs for an open or short in the lamp filament.
  5. Inspect the wiring for broken or partially broken conductors inside the insulation which could cause system malfunction but prove to be GOOD in a continuity or voltage test with the system disconnected. These circuits maybe intermittent or resistive when in use. The circuit should be monitored for a voltage drop during operation.
  6. Inspect for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer to Checking Aftermarket Accessories ).