2004 tahoe side view mirror heater leads

[Vincent Mitchell]

I just popped off the passenger side mirror because it's cracked. two leads are attached to the mirror, I assume they are the leads for the heater element in the mirror. I hooked up a meter to the leads and they seem to be supplying voltage all the time when the key is in the ignition. It's almost 80 degrees out today and there is no good reason for the heating element to run. Can anyone tell me what is supposed to turn on/off the heated mirror circuit? Thermostat? Switch?

 

[Fless]

When the rear defroster grid is turned on, the heat in the side mirrors comes on.

 

[Doubeleive]

pretty sure that's normal my 00 did the same thing

 

[Vincent Mitchell]

When the rear defroster grid is turned on, the heat in the side mirrors comes on.

Is that turned on by the defrost button in the center under the air? If so, I turned that off and power still remained. Maybe I havee a defective switch/relay or something?

 

[Fless]

The rear defroster button, not the front defroster, not the HVAC air defrost.

 

[Vincent Mitchell]

The rear defroster button, not the front defroster, not the HVAC air defrost.

If that is the button right below the knob that controls the air ducts then it must have a problem. It doesn't matter whether that is on or off, the mirror is receiving 12v

 

[Fless]

Post a pic of your heater and electric defroster controls.

 

[Vincent Mitchell]

Post a pic of your heater and electric defroster controls.

Here it is:

 

[Fless]

I'm not sure about the constant voltage, but that's the rear defrost button and that should control the mirror heat.

EDIT: would need to see a wiring diagram to see about the voltage.

 

[Vincent Mitchell]

I'm not sure about the constant voltage, but that's the rear defrost button and that should control the mirror heat.

EDIT: would need to see a wiring diagram to see about the voltage.


View attachment 261938

Yeah that's what I thought it was. I am reading 12v (or 14, but 12 makes more sense) even with that switch off. I am thinking some wiring is amis. I will try to dig up a diagram somewhere. Thanks for your help.