Rear defroster and heated mirrors do not work?

Hi,

I'm not sure where fuse 15 is, but I believe you meant fuse 56 which is a 15-amp fuse. If that is incorrect, let me know.

Now, if you have power at all fuses except 56, the problem either is the relay isn't being actuated due to a power or ground issue or there is a splice in the wiring to the fuse which may have failed.

Here is what I need you to do. Take a look at the schematic you sent, and I attached below. Remove the relay. Once the relay is removed, check connector pins 1 and 3 for battery voltage. With the key on, pin 1 will have power. Pin 3 will be hot at all times.

If both have power, the next thing to check is pin 2 for a ground path when the defroster is turned on. If there is no ground, the relay will not work, and power won't be sent.

If there is ground, as a test, take a jumper wire and jump pins 3 and 5. That should turn on the defroster by manually bypassing the relay. When you do this, confirm if there is power to fuse 56. If there still isn't, we need to check the splice.

If there is no ground, we have an issue with the defroster module.

Let me know if this helps or if you have questions. Also, here is a link you may find helpful and of interest:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

Let me know what you find.

Joe

Note: I attached three pics below all from the same page. I did this so they are readable, and you can follow them. I have arrows pointing to the power flow and highlighted areas of interest.

The wiring in the pic doesn't appear to be factory. Is this something that was added? Also, when you check the ground, do you mean the test light bulb was dim and flashing? Was it a steady flashing or did it seem like it could be a poor connection?

Let me know.

Joe

Hi,

I'm not familiar with your test light, but it appears that you are receiving a very weak ground. Now we need to determine if the problem is at the module, the grid, or if we simply have a wiring issue.

So, disconnect the EMTC (electronic manual temperature control) module and check for continuity in the wire. If it checks good, with the module still disconnected, check the continuity between the module and the white wire with an orange tracer at the window grid connector.

If the wiring is good, go to the grid connector, and confirm continuity between the white/orange wire on the grid and ground. If that is good, suspect the module.

I need to know two things. First, does the vehicle have factory navigation? Also, is the rear window a slider? If it is a slider, check the connectors at the grid to make sure they are not damaged. I'm starting to see them fail/break on the window grid connector pins.

Let me know so I can get you the correct location of the module.

Take care and I hope you have a good Thanksgiving.

Take care,

Joe

Hi,

It's difficult to know what you are looking at in the pic. Here is the part number from my manual:

Ford part number 19980.

To replace the part, it is located at the top of the dash. I attached directions below for replacement.

Let me know how things are going.

Take care,

Joe

See pics below.

Hi,

I wasn't far behind. I started in 1982. LOL As far as keeping up is concerned, it's nearly impossible. As far as replacing the module, yes it needs to be reconfigured to match your vehicle.

The fuse you indicated not having power will not get it until the rear defroster relay is actuated. Once the relay switch is closed, power is then sent through the fuse to the grid.

Let me know if that helps. Also, please understand that not being there makes this difficult for me. I always second-guess myself because I didn't physically do the testing. My suggestions are based on theory. Especially in this case where you need to get a module. I'm not a person that likes spending other people's money.

Regardless, let me know how things work out for you.

Take care,

Joe

We can handle one question per car, this is a new vehicle. Please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Cheers, Ken

I see, if the scanner has a full CAN controller scan and is bi-directional it should work. Please let us know if you need anything else to fix the problem.