GM Service Manual Online
For 1990-2009 cars only

Each outside rearview mirror has a mirror motor pack. Each mirror motor pack has two reversible motors. Each motor contains an Electronic Circuit Breaker (ECB). ECB resistance increases if a motor is overloaded and returns to normal after voltage is removed from the motor. One motor adjusts the mirror view up and down, and the other motor adjusts the mirror view right and left. The outside remote control rearview mirror switch controls the polarity of the voltage to each of the motor pack. The outside remote control rearview mirror switch has a mirror select switch which directs B+ to either the LH or the RH outside rearview mirror