Driver side mirror defrost not working

[thefrey]

My driver side defrost mirror isn't working, as evident by the recent ice events.

I have a Denali... the auto dimming is working and I can move/fold in the mirror just fine. But the defrost doesn't work. It works just fine on the passenger side.

Would this be a contender to replace the mirror/glass, or is it perhaps something electrical related? I am not sure the best way to go about diag for this.

 

[RST Dana]

Pop out the glass and check voltage with the defrost activated. No juice means bigger issues than a new mirror glass.

 

[Doubeleive]

My driver side defrost mirror isn't working, as evident by the recent ice events.

I have a Denali... the auto dimming is working and I can move/fold in the mirror just fine. But the defrost doesn't work. It works just fine on the passenger side.

Would this be a contender to replace the mirror/glass, or is it perhaps something electrical related? I am not sure the best way to go about diag for this.

not sure if there is a specific fuse for the driver mirror defrost, but you could pull the mirror cap off and test for continuity on the glass and also test for voltage when defrost is activated. you could also inspect for any corrosion on the connectors.
note the defrost tabs are separate from blinker and blind spot, the tabs should be the ones closest to the stalk.
defrost voltage should be 5v, but not 100% sure, that's about what it should be though..

 

[Alpha Mike Sierra]

I had a similar issue with the Passenger side mirror. It ended up being one of the three bladed fuses was half blown. There are fuses for the mirrors on the driver and passenger side panels that are only accessible when the door is open.