Wondering if anyone has run across this problem or may have an idea on where I can find the fix.

Rear Window and Side Mirrors will not defog. Last year the snow would melt right off and you couldn't even touch the side mirrors if you had the defogger on. The first freeze we got and the defogger isn't working. Great timing.

Things I checked:

-Back window is up (tested via working windshield wiper)

-Fuses are good.

-Wanted to test relay switch but wasn't sure how.

I took it to the dealer yesterday and guess what they said after 4hrs of having the car. "We don't know whats wrong"(The only thing they tested was the connectivity between the filaments in the rear window). After he said that he just stood there like I was going to say "that's okay not a big deal". I felt like I was pulling teeth just to get him to say "we'll do some research and see if we can find anything posted".

I would like to go back to the dealership and say not to bother as the 4runner.org brotherhood had the answer.

Thanks

thought I'd push this up front one time to see if anyone had an answer to dilemma.

thanks

Open and shut rear hatch one more time. Roll down rear window and back up one more time as well. Seem to remember something on my 4th Gen about this.

Are you still in warranty? If yes, take it to the dealer and insist it be repaired. He's being an arse, but honestly I don't understand why you put up with that treatment!

Does the light even come on on the switch?
dealer:"We don't know whats wrong"!!!!????

The whole trouble shooting step by step procedure for troubleshooting"Mirror Heater does not Operate with Mirror Heater Switch"is in the repair manual under Exterior/Mirror/Power Mirror Control System/Problem Symptoms Table.

Maybe find a dealer where the mechanics can read.

Have a read:

2010 Limited tailgate is on the fritz

Hi Harper7,
Light is on when pressed and the only thing I get is some warmth from the mirror. It's my recollection that the last time I used this accessory you couldn't even touch the mirror because it was so hot. Is this true with your limited?

Hi Ryan1975,

I did try this and the window washer and wiper do work.


Hi Philsey,
Yep, still under warrantee only 23000 on the vehicle.
Actually didn't put up with the answered given. Found my blood pressure rise when I was typing out the full details and decided to delete my full reaction. My rant was obvious to the service department. I may visit the Toyota dealer that I purchased the 4Runner from and hope their customer skills are more acceptable.

This sounds like a bad connection is acting like a resistor, dropping some of the power to the heater elements. A simple continuity check will probably not detect this. It could be a bad switch(contact problems) or connections to the switch. Check for the switch being warm to the touch. Also check if the fuse is warm to the touch. If the fuse is warm then replace it and test the defrosters.

Just some ideas to try.

I tried mine out last night to see if it actually got hot as I never really tested it.It has always defogged the mirrors and we don't get much winter precip down here so I never really thought about it.

It was about 40F out and mine were just warm to the touch .They have a 15 minute timer and I tried them twice. Are you sure yours got "hot" before, as the manual check for them is to see if they get "warm". Maybe somebody else verify that they just get warm and not hot.
Here is the check from the manual if you want to check it with an ohmmeter(starting at (b).Of course you have to get to the connector first which is the hard part.lol

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Seems to me if all 3 do not work, it should be something common to all three, eg a fuse, the switch, or power to/from the switch.

Does the switch STAY lighted after pressed?

Thanks harper7 much appreciated! I dig around for my multi-meter and do some testing this weekend. The side mirrors were definitely very warm to hot. Now there just ever...so...warm. I might do another thread asking if side mirror option 4Runner owners experience to the touch warm or hot output.

Hi Philsey,
The switch does stay on for 15min. The mirrors and rear defogger have independent fuses and relay switch. The commonality (that I can see)would be the on-off switch.

I tried this out for you last night, it was ~43F out and I left it on for an entire 10-15 minute drive. When I got out it was only warm to the touch. Perhaps you felt it being "really hot" when it was extremely cold out and your fingers were freezing?

In case you are curious and wanted to poke around with the DMM, the relays for the mirror defroster and rear defroster are all under the hood in the larger fuse box. If you pull out the relays, I believe the cooper terminals are the ones that connect the heating elements directly to the battery and the tin terminals are the relay's coil. So perhaps you can start by testing if it's getting a clean 12v signal to the heating elements etc... in order to rule out a few factors before having to dig deeper.

You are correct in that there are separate activation signals for each relay individually. The relay activation signal comes from the a/c amplifier assembly behind the glove box, and are switched ground outputs to activate the relay.

Thanks!!! Fixed mine because of this thread.

Did anyone get a detailed resolution to this problem? I have a 2010 SR5. The mirrors might get a little warm, but the rear window defrost doesn't seem to be working at all.
My defrost light stays on and I know the window sensor works because when I roll the window down the defrost light turns off.