Wipers won't park. Other electrical ghosts. 86

[Whosondephone]

Since I bought the 86 Mercury the wipers never parked. The interval and speed work fine. When I switch off the wipers they just stop. I believe they should finish their cycle then park. I bought a new wiper motor thinking that might be the problem. Still have the same issue after installing it. I have a scan of the electrical layout however it doesn't give any info about the connections. Just where they go. It doesn't say where the boxes are located either.



The Handy instruction sheet that came with the new motor simply says there must be an open wire. I might try contacting the manufacturer and see if I can get more info. Or just probe around with 12V on the old motor and see if I can get it to spin backwards. Can anyone shed some light?

I do have some other electrical glitches. Perhaps related. The rear defroster never worked right. I had to disconnect it because it would drain the battery. Also the warning chime (for lights and keys ect.) is very quiet, seemingly inaudible. Lastly there was a strange small black wire running to the negative post on the battery. This must be some kind of repair. It triggers the fuel pump and relay network under the hood on the driver side of the car when the key is on. Is that wire from the factory?

[DerekTheGreat]

Don't know about the motor or your defroster issue but the warning chime is dying; Ashley's didn't work right and it turns out there's a foam ring around a small metal diaphragm thing that vibrates to make noise, this foam dry rots and then the thing doesn't work so great any more. I've got a spare. That black wire you mention is the same one my '85 LTD had so it is probably factory.

Oh, my wipers try to park but they stop about halfway into the sequence, was told a new motor would fix that but I've done so much other work so I haven't been able to get around to it. Might do that next month.

[gadget73]

The rear defroster switches go bad. They are supposed to have an internal bit that pops the catch and shuts the defroster off when the key is off. After a while this doesn't work right and the defroster stays powered. New switch should fix you up. Mine was bad when I got my car, and it would run the battery dead very quickly. I fixed it just as quickly after getting stuck one too many times.

There is a small ground wire straight to the battery from the ECM. It goes through a connector that looks sort of like a fuse holder. This one is needed or the ECM won't work correctly. DOes it look like it goes into a factory harness, or is this some random single wire that looks obviously kludged in?

Not sure on the wipers, but it could be a whacky switch, or possibly the governer. Normally if the park cam in the motor is the problem, the wipers will refuse to shut off. If it just stops wherever you hit the switch to off, I'm thinking the switch is wonky. It somehow reverses voltage to the motor in order to suck the wipers down below the glass. I've honestly never looked into it all that close, but my bet is on that being it.

[Whosondephone]

The Small Ground wire is just like Gadget73 said.

There is a small ground wire straight to the battery from the ECM. It goes through a connector that looks sort of like a fuse holder.

I am now sure it is from the factory. It joins a group of wires from the Key solenoid that are electrical taped all the way up to the windshield. Then they go into the plastic harness.

My battery overflowed and corroded the terminals. I changed the battery and relocated The above mentioned Black wire to the bass of the starter solenoid. It's hard to tell yet if this is effecting performance. I just cleaned out the Intake and idle control motor. It Idles better. However it does seem to be putting harder but less often at low RPMs under load. I'll need the climate to change until I reach the final verdict.

Cardone, the wiper motor manufacturer, HOPEFULLY faxed me a bench test at work. I'll have it tomorrow it It came through.

I had hoped that the defroster was just a switch. I guess I tackled the wrong problem first. I didn't think anything could be that simple.

[gadget73]

You really want that going straight to the battery. The ECM uses that for voltage sensing stuff, and it will mess with injector pulses and other stuff if its off.

[Whosondephone]

Soldered that black wire with the main ground line to a new solid copper battery terminal connector. Runs much smoother.

Here is the secret information on the wiper motor from Cardone:



I'm expecting to have to wire up a button if I want the wipers to park. Hopefully I'll mess around with them tomorrow.

[Whosondephone]

I did some probing/testing today. I could not get my original motor to park however I got the new one to park by following the Previous instructions. Here is what I have found.

I believe the following information to be true if the wiper system is working:

In order to Park:
+12V T4 (always supplies +12V with key on)
- 12V Chassis ground
Jump the following:
T5 - T3 [I measure +12V until park]
T6 - T2 [no voltage assumed ground]

Low Speed:
T2+
T3-

High Speed:
T2+
T1-

The interval seems to be working properly on my wiper motor.

Interval:
T5 +12V while moving
T6 +12V While not moving
T4 +12V At all times

The following information was taken from a dysfunctioning system:

When the motor is in park position, switched off, and wired up I get:
T6 +0.5V
T4 +12V
I neglected to measure T1 through T3. I should do that.

When switched off and motor is not in park position:
T5 +12V
T4 +12V
T1 +2.8V
T2 +12V
T3 +4.5V

The chassis schematic from the book makes no sense. There seems to be an extra wire in the book (other than ground) and different colors. I find this to always be the case. They use the same schematic for all other years the book clams to supply information about. Perhaps it was never updated. I could not locate any of the governor/control modules assumed to be under the dash. I might try looking at the switch on the steering column...

[DerekTheGreat]

You really want that going straight to the battery. The ECM uses that for voltage sensing stuff, and it will mess with injector pulses and other stuff if its off.

Which wire is this? My car didn't have the original + connector or cable when I got it and I switched it to one without those chincy $3 connectors. This cable connects right to the starter solenoid which then has all the other eyelets that supply power to all the other stuff. Yesterday I was prewiring my car for the 3G swap and I didn't see any wire long enough or evidence that one had been modified to go to the starter solenoid. Ground cable to battery does have a smaller wire tied into it that is bolted to the core support near the radiator. Car runs and drives just fine aside from that occasional stumble off idle or weird surging if you just slightly press into the gas and hold that position. I've noticed that Ashley's does that now too. We both have similar set-ups.

[gadget73]

Its the skinny wire on the negative cable.

[Whosondephone]

I've practically replaced replaced everything except the switch and two transistors in the control modal. I've come to believe that the problem is the switch like gadget73 mentioned. I've had an 86 Cougar that when you switched off the wipers sometimes the wipers woulden't park. You would hear the wiper motor straining. You would need to run them for a cycle and try again. Sometime it could take multiple tries. I used to wonder what would happen if you just left it struggling. I guess the switch burns out. But there still could be something wrong in the control module.

Edit: Just throwing some keywords for people searching for such a thing:

Wiper motor Schematics Schematic

[gadget73]

The module is for the intermittent wiper functions. It should have nothing to do with the parking system.

Looking closer at this, it appears the dark green wire is what supplies power to the motor for parking. Might be worth checking for voltage there. The only other thing seems to be the parking switch in the motor itself.