topless
i hope you got it figured out already, if not....................
I recently experienced a non heating drivers side mirror. passenger worked fine and the drivers dimming feature worked. mine turned out to be a bad heater on the back of the mirror. the circuit read open. (i did not read the new heating element resistance)
First, what is supposed to happen:
When the rear window defroster is turned on, the outside mirrors get the same B+ voltage (12v or more). the voltage comes from the same relay & fuse. so if one mirror heater works, then the system is supplying the correct voltage (relay & fuse are good). the two mirrors have different ground paths however.
when you look at the small black mirror connector (on the back of the glass, with 4 wires)
1&2--> auto dim
3--> heater ground
4--> heater 12v
Only one side of the connector has numbers on it, i forget if it is the door side or the mirror side, check that you have a good ground on the door side on socket #3 and 12v on #4. if you do, then it is the mirror glass/heater.
I doubt that is your issue since you have 3 mirrors that don't work, but check it first anyway. if you are missing the 12v or ground, chase the wires back to find the open/short.
Thx to yzark99 for this
https://www.camaro5.com/forums/showthread.php?t=297215
attached are some pages from the shop manual, good luck!