The garage remote buttons on my auto-dimming rearview mirror have stopped working. The auto dimming feature still works so it's getting power to the mirror.
I've tried removing and reconnecting the wiring harness to the mirror to no effect. It doesn't look like the mirror comes apart to inspect the internals.

I had 2 buttons programmed to my 2 garage doors. Neither of them now work
The little led light does not illuminate when I press any button, nor when I hold down any button.

This is a factory option. I did not retrofit it.
Short of sourcing a used mirror - anyone have any ideas how to troubleshoot it further?

 

Sounds like it needs a battery, perhaps?

 

It’s hardwired.

There was a thread recently regarding flaky keyless entry where someone popped the mirror apart and found corrosion on the PCB inside, so they do come apart. Or at least the manual dip mirrors do. Apparently the corrosion issue isn’t unheard of. Perhaps you have a similar issue with the homelink module.

I don’t have a ton of experience with that system though. I retrofitted the autodim mirror with homelink to my car a couple of years ago, but I rarely use homelink portion because we have a carport. I don’t know if it can forget the door code, but it seems like the light should come on regardless.

 

Just to loop back on this. The R53 auto dimming mirror does indeed come apart. I pried it open using trim panel tools.


Disassembled R53 auto dimming mirror


The homelink module (left of centre) appears to be in good shape. No loose connections, no loose solder or any corrosion on the PCB.
I ended up going with a replacement mirror from a scrapyard as I couldn't see anyway to repair or replace the homelink module.

Thanks