Hello all, My 2002 f150 did not have the heated mirrors or rear window defrost. Those options were not available even though up here in a canada winter they should be standard. Anyway I have discovered that most parts are interchangable between the f150 and the Expedition 1997 -2003. My question is this; I see that the switch is on Ebay, is the timer built into the switch or is it a function of the Gem module. I can get the expedition switch alone or I can get the dash bezel with it built in, or I am also looking at the switch from the Windstar/Explorer.

 

In this 2003 diagram, the computer in the cluster controls the heating function.
AutoZone.com Repair Guide Image Window Defrost (2003, Excursion)

If you want to hunt around some more, go to autozone's site and register, and go to vehicle repair guides. They have pretty good diagrams for those years.

 

Excursion is a Super Duty. You can bet that an F150 is completely different.

For example, in the 02 Expedition, the timer is in the Gem module. If you want to retrofit an F150 for heated mirrors, you'll have to do the whole control circuit from scratch, likely including all the needed harnesses.

 

In the GEM module is what I figured. However I have just come across info about the defrost switch for the 91 -94 explorer that has the timer built in the switch. Figure installing that one in the spot where the four wheel drive control would be which would place it directly left of the heater control. Or opening it up, removing the timer and hardwiring the timer to the expedition switch and swapping in the dash trim bezel from the exp to the f150 although I don't like the left of the steering wheel placement.

 

Yep, I found the wrong diagram.

If you want to wire this yourself, in another thread a guy had a link to this website that has 12v timing relays at a very reasonable price. Here's the link.
Automotive Time-Delay Relay