Why you have brake and tail lights when head are turned on 1997 GMC?
There are a few reasons why brake and tail lights turn on when the headlights are turned on in a 1997 GMC:
1. It's illegal not to have your tail lights on at night; 2. to make sure the driver behind you know your car is stopped;3. so you may been seen coming when changing lanes/pulling to a spot, etc.