Heated mirrors drain my battery.
 

Since I got my 03 silverado a few years back I have had problems with the battery. Once in a while I would find the truck with battery drained. It could go months between each time and whenever I checked with an amp meter everything was fine.. Until this Thursday when I had recharged the battery after drain situation and did a measurement. With no keys in the truck and all lights off I saw almost 3A draw from the battery. Was able to trace the current to the heated side mirrors that where really hot.
Mirrors are getting power for the heat from the DDM(Drivers Door Module) and PDM(passenger door module). There is no button for the heated mirror and I am pretty sure they are ment to operate together with the heated rear window. To activate the heated rear window I had to switch on the ignition. Heated mirrors remained ON after I had turned the heated window on/off several times.

I've now disconnected the wire at the terminal at the mirrors. but I need some suggestions on how to solve this permanently. I know I can wire up a new separate switch but I would rather like to find the root cause of this problem.

Is it correct that the door modules get commands from the BCM to turn on/off heated mirrors? If so, why would it turn them on? What tools is best suited to read messages sent to the DDM? I've done some research and it points me in the direction of Tech2 or vxdiag with a tech2win software on the computer. Also there is so many programs out there and I have problems understanding which of them to use for what. GDS2, TIS, TIS2000 etc. anyone care to explain? I'm not that experienced in GM trucks/cars. I have a efilive that I used to tune the truck but it can only be used for ECU related operations as far as i know.

When I removed the mirrors to disconnect the heater wire I managed to make a smal crack in one of them. Only a tiny one that you barely see, but I think it is a reason to replace them with mirrors that has turn signals. When I looked at the wiring diagram for the DDM there was some wires there for turn signals which was not present in the harness on my mirrors.. Is this plug and play or do the DDM need to be programmed for turn signal mirrors? If so, what do I need to do that?

There must be a relay for the mirrors, and it sounds like the contacts in the relay are welded shut.