Two problems related to headlight switch have been reported for the 1996 GMC Sierra. The most recently reported issues are listed below.
Headlamp light switch works on and off, making it hard to drive at night. The lights would go out while the vehicle was in motion. The unit required that the turn signal had to be replaced.
Both hi and low beams of headlights went out while driving vehicle at night. Went to dealer next day. Dealer charged $502. 65 to replace headlight dimmer switch. Wiring was melted and burned on switch. This could have started a vehicle fire, or caused an accident. Fuses and circuit breakers did not protect vehicle wiring. Switch is available if you would like it for examination.