GM Service Manual Online
For 1990-2009 cars only
  1. Inspect the circuit breaker to determine if it is open. If the circuit breaker is open, locate and repair the cause of the circuit overload and replace the circuit breaker.
  2. Inspect the dome lamp switch ground to make certain that it is clean and tight.
  3. Inspect the lamp filaments to make certain that they are not open or shorted. Replace the lamp if required.
  4. Inspect for a broken (or partially broken) conductor inside the insulation which could cause a malfunction but prove GOOD in a system test for continuity or voltage. These circuits may be intermittent or resistive, when loaded, and if possible, should be monitored for a voltage drop when the system is placed under load.
  5. Inspect for proper installation of aftermarket electronic equipment which might affect the operation of other equipment.