I'm having a problem with the rear defroster and heated mirror circuit. The button on the dash does not light when pushed, and defroster is inoperable. The dealer said I need to replace the glass on the rear slider due to a weak contact in the defroster.
However, I tested the contacts with a volt meter and I am not seeing any voltage.
How can I trouble shoot this? I see there is no common fuse for the circuit, but there is a hi-power fuse and relay under the hood. Before disconnecting the battery and having to go through steps to re-cycle the engine, isn't there a way to see voltage coming from the switch on the dash to the slider?

Thanks

 

There are several post on here with the same problem. I have a 2011 doing the same. I do have mirror heat though. In most cases, it is the rear window switch on the sliding window. If you are in warranty, take it to the dealer.
I have chosen to live with out it rather, than spend the money to replace the rear glass.
There appears to be a magnetic switch in the fixed frame on the drivers side. I assume this is where the problem is. Also be sure your rear window is closed all the way.
defroster not working - Ford F150 Forum - Community of Ford Truck Fans
http://www.f150forum.com/<wbr>showthread.php?t=273167

 

Anyone know is there's going to be a TSB on this issue? It seems way too common for Ford to just ignore it.

 

Hi thzpcs,

I recommend staying in close contact with your dealership. They'll be the first to know if any TSBs are released. If you provide them with your VIN, they'll be able to see if any service actions would apply to your vehicle.

Crystal

 

I just got my 2013 F-150 eco back from the dealer after two days in the shop with the same problem. The rear window defroster light would come on and then go out, and then eventually it would not come on at all. I was told by the Ford service rep that the rear window would have to be replaced because of high resistance in the grid wiring. This is after they removed my door panels to check the wiring to the outside mirrors, and replacing a module in the dash somewhere. The service department called Ford and spoke to their engineers and were told to replace the window because of the wiring. I'm lucky it's still under warranty.