Another rear wiper thread..

[ExploreHudson]

Hey yall

Really trying hard to get my rear wiper/washer to work.

I have replaced the switch. I have replaces the wash reservoir and motor.

I have bypassed rear glass safety switch.

I hear nothing from wiper motor or washer motor.

I have checked fuse. When i check for voltage, i am only getting like 60mV. Should i be seeing 12v? Sounds like a bad relay or module to me.

Questions:
1. Is there a rear wiper relay?
2. Does the GEM module control the rear wiper?

Thanks a bunch yall

 

[ExploreHudson]

So i found 3 relays under the power distro box. Not sure which is which.

According to this schematic, i should have a circuit breaker between the 15A fuse and the switch itself. Where is this circuit breaker? Maybe thats what has gone bad on my X

Thanks again

 

[BKennedy]

What voltage are you seeing from the red wire with the key on? Are you getting any power from the switch to the motor? The switch wire is white at the back right side of the head liner. You can also check the red wire at the same location.

 

[ExploreHudson]

Thing is.. I dont think I am getting the right voltage at the switch. Unless the switch just sees enable/signal voltage. I read ~60-70 mV at the switch. Still looking for that inline circuit breaker..

 

[ExploreHudson]

Still cant figure this out. With all 3 relays removed from under the distro box, i can still turn on the front wipers. The measured voltage across the defroster circuit switch is 12v. The measured voltage across the rear wiper switch is 100mV.

Ive tried different fuses, relays, etc. Its not a hugely important feature of the car, but i dont like to give up on a problem.

 

[BKennedy]

Firstly, does the washer work?

I am starting to think your switch is faulty, but you should check the connection at the dash to make sure its connected. If you pull lightly on the bottom corner of the dash cover near the switch, it should come loose enough to check the switch connectors. Remember, I said lightly. I recently used that wiring for another project since my rear wiper was removed many years ago when it stopped working. The red wire is key on 12 volts, and the switch wire (white at the plug) is key on, switch on 12 volts. I know this because I was thinking of using the dash switch for the other project and checked its voltage. Switch wire runs to a built-in relay at the motor, red wire is much heavier and carries the amp load.

If the washer works, try bypassing the switch by running a jumper from the washer switch wire to the wiper motor switch wire, turn the key on and flip the switch. If the wiper works, its the switch. If the washer is also not working, you can jump the switch wire with the red wire and turn the key on and see if the wiper works. Same with the washer.

 

[ExploreHudson]

I replaced the switch, but tested both with a mm and they are both good.

I put in a new rear washer pump and reservoir as well. Still no dice.

Just fyi, my front wipers and washers work fine. I just hate having a button that doesnt actually so anything

I think one of my front relays may be bad indeed.. perhaps one of those 3 relays under the distrobox controls the rear wiper/washer?

What is weird is that I actually get a negative 100mV from the wiring going TO the dashboard switch. The relays are not interchangeable because they have different pins. Some on here have suggested changing them as a method to troubleshoot, but it doesnt seem possible. Should I just go pull some junkyard relays and try them?

 

[ExploreHudson]

So the 3 wires going to the rear wiper are red white and black. Im not getting any voltage in any scenario from red or white.

Scratch that. 1mV detected. Seems like leakage voltage through a failed relay. I think Ford hid a relay or circuit breaker somewhere.

 

[BKennedy]

I think there is another plug to those wires, other than the one at the rear of the headliner. If I remember correctly, its under the driver side interior panel, on the C pillar, or a little behind that. The wiring runs from the main harness in the floor, up the backside of the C pillar and under the headliner above the cargo windows. If not, its on the opposite side. You will have to pull the shoulder harness bolt to get enough room to get behind the interior panel. If you pull down on the headliner a little with the top of the rear panels loosened, you can see the wires and where they go. I had the main dome light fail to work and it turned out it was a loose pin in the plug under the A pillar interior panel.

 

[BKennedy]

I looked in my electrical wiring book for my 1994, and the rear wiper power and switch power come directly from internal fuse block #17. The wiring to that does not go through any relays, and also powers most of the fuse block. If there were any issues going to the fuse from the battery, it would also effect most of the fuse block. Your issue is either the wiring from the fuse to switch, to motor, the inline circuit breaker after the fuse, or the liftgate wiper disable switch which I believe is located in the lift gate. If you are not getting any power to the lift gate, that narrows it down. I think you have a faulty plug or ground between the fuse and the motor. Its more likely a plug because the harness grounds at multiple locations. Start at the back and work your way forward. You can access the main wiring harness by removing the driver side B pillar and floor interior panel, its all one piece.

 

[ExploreHudson]

It is definitely between the fuse and switch. I get 12v on both sides of the fuse. But 1mV at the switch harness plug.

I tried to just remove the switch wiring, but it looks like it may go off to the wiper control module/governor or something. The wiring from the fuse box goes to a connector which goes to a cable that is wrapped with the big harness going toward the center dash. Then it comes back from that direction and into the left side dashboard hole for the switch.

The wire in question, white and purple. There is not a red wire going to the switch plug.

Anyone who has taken the dash out.. who maybe has some pics... what color wires go into the gem module or wiper governor? I think i may just use the defroster power to test the rest of the circuit

 

[ExploreHudson]

SOLVED

ish

Okay so im glad to report back that my rear wiper and washer are fully functional now.

Heres a video i made explaining the issue and how i circumvented the faulty circuitry. There is definitely a circuit breaker or something up in the dash somewhere. Its in my schematics for this year X. Anyways.. heres the vid

 

[ExploreHudson]

Also I am really sorry about the video formatting. Big noob here!