rbailey3711

Just to add to Feathermerchant's comment:
The driver's side window does get the hottest and I found that the timer circuit in the control unit DOES NOT turn off after 10 minutes like the owners manual states. Ford kept my old window, you can go back in these threads and you'll see diagrams. We also have resistance reading back there as well. You can also use a heat gun to warm up the cover to melt the silicon glue a little. Warning: it still didn't work and one of the tabs broke off anyway. If that happens after you fix your contacts, a little dab of Gorilla Glue will adhere to the tab piece left behind the contacts.
Back to my statement about the control circuit; because the timer wasn't shutting down the circuit, the coil in the driver's side rear window opened up. Again they kept my window and when they gave me a better than $600-$800 dollar offer to replace it, I took the offer [it's quoted back in the thread, I think it was $383]. Also Ford didn't say anything about my glue job on the cover . I was able to clean the contacts and bend them to make better contact using a wooden q-tip and some contact cleaner. As I said, the driver's coil was open so the window circuit wouldn't work but the heated mirrors still worked.
Feathermerchant has done a great job helping folks involved in this thread and he provided copies of the schematics for troubleshooting. Thanks for your help Feathermerchant.

DaveRiedel

I think we are talking about two separate issues and maybe two separate designs.

The schematic that is floating around matches my truck with the exception of the 4 volt signal wire coming from the glass to the plug (pin 1). If the schematic is the same as other years the heated window cant stay on with the rear window opened. The only way this happens is if there is a failure in the HVAC module. This module is also the source of the timer. In the schematic they refer to a heated window, I would assume that is the side mirrors, right? If so can anyone confirm that the mirrors wont heat with the window open.

I am not trying to dissuade anyone from the issues rbailey3711 was having. If my problem behaved as his I would not have resolved it in the way I illustrated. A ohm meter reading can confirm that the glass is bad but cant confirm with certainty that it is good (I can explain if desired). In my case the only way to get right to the issue was to hot wire the defroster and check voltage readings as it made its way across the defroster grid. That led to the contactors and nothing else.

As an FYI the grid pulls 14 amps when working, given the voltage is a bit less than 14 the resistance of the 3 panels would be 1 ohm. To an ohm meter that will look like a short. If you test this way one would close the window, unplug either the supply or ground wire and read the across the entire window. If there is an open check each panel if they all read very low the contact is the likely source.

Feathermerchant

If the rear glass heaters pull 14A and have a resistance of about 1 Ohm, then that is about 200W or about 70W per panel. That is a lot of heat.
What I was suggesting above is that the glass breakage may be caused by high resistance at the contacts creating a lot of heat in one isolated location. If those with failed glass can confirm that the drivers panel (where the contacts are) is what always fails then the contacts heating seems to be the cause.
If the elements have only 1 Ohm of resistance, then the contacts have to be about perfect (0 resistance) in order not to get hot. A 12ga wire should be large enough for 14A and pretty flexible. I'm not talking automotive wire but some specialty wire that I have access to.

DaveRiedel

I completely agree. The 70 watts per window inst really that bad as it spreads out the heat. A bad connection would be at a pin point and could develop a whole lot of heat and then maybe very little as the resistance climbs. That is the point of the 4 volt signal, if all things are not perfect the voltage will be altered and the module will shut it down. This is why I wonder about folks who can run their rear view mirrors. It makes me think we are looking at two different circuits.

I didn't address your desire to wire your contacts together as I thought my way was less intrusive and easy to install. There is no question that what you suggest will work and indeed work better, it is implementing it that concerns me. If I were doing it I would look for a copper foil that can flex with the window movement but rigid enough not to sage. One might even need a valance to protect them from physical harm. This stuff isn't cheap and i cant really tell you what would be the best thickness for rigidity.

One other idea is to use 8 pieces of #22 or #20 300 volt STRANDED wire. This wire is thin enough to get under while doubling the wires per contact will provide a healthy current path. They will flop so again a valance might be needed to protect it from catching. I would assume the black cover would have to be removed and the contacts pulled away to get the soldering done.

Send me a photo if you do this, it will be some effort but done right it would be the **** retentive fix. Let me know if you need some more clarification.

Dave

Feathermerchant

I was thinking about that flexible circuit board like stuff that is used in machinery.
They also make a flexible conduit. Kind of a flexible valence. Maybe multiple conductor flat wire. Something like your typical boat wiring harness.
It's 24 deg F here today so I'll wait for it to warm up.

KR-Shannon

Having the same problem with my 2012 F-150. So the cheap fix is to bump the slider open and then press the rear defrost button on my center stack?

DaveRiedel

To be honest I did rig it up as mentioned and a week or so later the passenger window shattered. I replaced it with Plexiglas which isn't very pretty but for now it works.

Given this there is little doubt in my mind that the voltage running through the window is getting shorted to ground probably at or near the center window. This puts full current across the passenger side glass and heats it up to the point of shattering. It is pretty common and I suspect if you do as I did your window will also shatter.

I have not bothered with it since and haven't found the short so until I dig the whole window out I wont know where the short is but it is there.

Dave

Ynot4me2

Sadly, there's not much you can do except replace the entire rear window. around $1K or live without the rear window defroster as some of us have been doing. At least you still have the mirror defroster. Haven't found a fix yet.

KR-Shannon

I'll live without it.

rbailey3711

They do make repair kits if it is in the grids. I still think it has something to do with the timer for the rear window defroster in the dash unit. If it doesn't time out and it keeps heating, then you have the probability of burning out the wired connection to the driver's side rear window at or near the slider contacts. I asked for my old window when it was replaced by the dealer, on my 2013 F150 Lariat, but they said they had to return it to Ford because of the warranty option they were using. I would have lived without if I'd had to pay the $880, my share was $380 something. [I think its back in one of my earlier posts on what I actually paid].
Boneyard finds may have the same issue and I haven't seen any aftermarket replacements available.
I'm curious on what they did to change the circuitry for the newer models; its an entirely different sized slider.