I literally signed up a minute ago searching for anyone in my same situation and found a tid bit but couldn't finish reading because of not being a member. Now I can't locate the conversation but I'll start my own.

The new heated mirror has five wires in a different style plug than in the original four wire plug. i'm pretty sure I can figure out how to get this working however I would like some examples of maybe what somebody else has done so I can eliminate some engineering skills. I've heard tapping into the rear defroster for the heater I've also heard of just stealing a positive from any constant pos. And adding a switch but I need it to time out for safety and not to drain the batt if left on. 97 gmc jimmy SLS. Thanks for any guidance.

 

On my 1999, the mirror heaters are on the same circuit as the rear window defroster.

 

 

My 98 is, too.

1998 was the last year of the "older" style mirror, and 99 was the first year of the elephant ear style.

It seems every version of mirror had different wiring, from what I've encountered.

I ended up just buying new ones from discountautomirrors.com ... pretty cheap, and have been working great for a few years now.

If you keep digging, I think there are multiple threads on here with wiring diagrams that can break down the differences in wires.

 

I had the original 98 power heated mirrors on my 98 LS 4dr when I bought it. The drivers side glass was cracked and the base had a lot of electrical tape holding it on. I got ran off the road and the passengers side mirror didn't survive. I went to the junkyard and looked for Blazers that not only had power heated mirrors but also had the 5wires to the mirrors like my 98 had coming out of the switch and into the mirrors. I got both mirrors off the same truck. I cut the wires below the connectors on both the newer mirrors. I cut off the black connectors on the 98 wires and tried several different color combinations. I could only get 1 direction and heat. What am I doing wrong? Do I need to use the black connectors and then splice the wires on the mirror side of the connector or what? What colors are supposed to go together. Please help! I drive at least an hour to and from work 7 days a week on the highway and hate the headlights in my eyes from the mirrors