Attempting wiper troubleshooting

AttemptingToBeAMechanic · Oct 28, 2016

I have a 1994 Ford Ranger with malfunctioning wipers.

At first the symptom was the wipers would not turn off. I thought the issue to be the MFS (multi-function switch), after replacing it from another truck I was told was compatible at the juk yard counter the problem was still not resolved, so I replaced the wiper motor. Now the wipers do not turn off and sometimes they don't turn on either. I've tested the relays (but i don't think a relay controls the wipers in this model). Even though the weird looking 6A fuse passes a continuity test, I have seen another post [1] that suggests this was the issue for them so I have ordered one. I saw in another post [2] that mis-matching MFS and wiper motors is and issue, so I am concerned about this as well.

I'd like to troubleshoot this issue more intelligently. I am new to wiring diagrams for vehicles. Can anyone point me in the right direction of understanding how to trouble shoot this component that does not involve changing every component until it works? Also what references should I be using if the Haynes manual is insufficient?

[1] http://www.therangerstation.com/forums/showthread.php?p=144572
[2] http://www.therangerstation.com/forums/showthread.php?t=115006

ericbphoto · Nov 1, 2016

My first instinct would be to check the "park" switch contacts in the wiper motor assembly. These contacts are what makes the wipers go to the "home" position after you turn off the switch.

AttemptingToBeAMechanic · Nov 17, 2016

I was originally looking in the "Ford pick-ups and Bronco Haynes Repair manual" which should not be confused with the "Ford Ranger Pick-ups Haynes Repair Manual". In t he diagrams of the correct manual section 12-28 I found the diagram labeled "1994 Body Wiring".

I confirmed the color of wires from the the MFS as in the diagram. The corresponding BLK/PNK is just BLK on the motor, BLU/ORG is just BLU, YEL/RED is just RED.

I'm attempting learning how to trouble shoot the MFS and the motor contacts by watching this video: https://www.youtube.com/watch?v=0KHUxiXn31s

AttemptingToBeAMechanic · Nov 17, 2016

ericbphoto said:
My first instinct would be to check the "park" switch contacts in the wiper motor assembly. These contacts are what makes the wipers go to the "home" position after you turn off the switch.

Can you provided any tips on how to do this?

AttemptingToBeAMechanic · Nov 17, 2016

AttemptingToBeAMechanic said:
Even though the weird looking 6A fuse passes a continuity test, I have seen another post [1] that suggests this was the issue for them so I have ordered one.

I replaced this fuse, and this did not resolve the issue. It was $26 and non-refundable after testing

AttemptingToBeAMechanic · Nov 17, 2016

AttemptingToBeAMechanic said:
I'm attempting learning how to trouble shoot the MFS and the motor contacts by watching this video: https://www.youtube.com/watch?v=0KHUxiXn31s

This video was ultimately not useful to me because I could not figure out what the different color wires in the vehicle that was being worked on correspond to on my Ranger.

I did make a few observations while trying to figure it out on my own.

Some of the wires that I think are associated with wiper functionality are not properly seated in the larger grey plastic wire-holder that connects directly to the MFS. It appears there are plastic tabs inside this grey wire-holder that keeps the wire terminals in place that have broken off. Should I replace this? What do I replace it with? I have manually pushed in these wires from the back of the grey plastic wire-holder, but have not done a continuity test to the Wiper Control Module. See attached photo.

I have also confirmed that applying 12v to the Blue wire of the motor makes the wiper motor run fast. Connecting 12v to the white wire makes it run slow.

Any tips on debugging this system more would be appreciated.

Doofy · Nov 17, 2016

You need to find a good u-pull-it wrecking yard and save yourself some money. $26 for a fuse??? Did it come with king crab legs and a t-bone?

ericbphoto · Nov 18, 2016

Can you provided any tips on how to do this?
Yesterday 12:58 PM

Most wiper motors I have messed with have a cover that can be removed to expose the slip rings and wiper for the park switch. Once removed, you can inspect and clean these parts. Maybe even clean them and apply a thin film of conductive grease to the slip rings to help prevent oxidation. you don't want anything to bridge between the rings. The ones I have seen are normally just copper traces on a plastic wheel.

AttemptingToBeAMechanic · Nov 20, 2016

ericbphoto said:
Most wiper motors I have messed with have a cover that can be removed to expose the slip rings and wiper for the park switch. Once removed, you can inspect and clean these parts. Maybe even clean them and apply a thin film of conductive grease to the slip rings to help prevent oxidation. you don't want anything to bridge between the rings. The ones I have seen are normally just copper traces on a plastic wheel.

I looked over some other notes from the internet on cleaning electrical motors. After disassembling the slip rings look a little worn, but are still making contact with the commutator. I had a bit of a hard time getting it back together, and it does not rotate after re-assembly so I am going to work on that a bit more. Do you see anything here I should take note of? I visually confirmed functional operation of the internal park switch while rotating the motor.

I also traced the 4 wires leading to the wiper motor and there does not appear to be a short of the Red or DB/O wires coming from the MFS or either of the RED of WHT wires coming from the Internal Governor.

Now that all of the lines are taced to the motor, can anyone recommend the next thing to test? Does anyone have anything to add?

Notes on photos:

I believe these are in the internals referred to by ericbphoto. I dont see anything the matter here.

The stator assembly looks fine to me too.

The slip rings are really worn, but they make contact. I cleaned then and the commutator with Electronic Cleaner.

The Internal Governor is the brown box behind the ashtray. You can get to it without removing any of the dash. There is a small clip you have to press in when removing.

AttemptingToBeAMechanic · Nov 20, 2016

Doofy said:
You need to find a good u-pull-it wrecking yard and save yourself some money. $26 for a fuse??? Did it come with king crab legs and a t-bone?

No it did not come with any of those things. This was for sure newbie tax that I hope to not pay again by learning better fault tracing techniques. I assumed that since it was such a random size and shape and that I could not find it in the local auto parts store, and that someone else in another forum replaced theirs and it fixed the issue, that it would be the last thing I needed to replace to get park working on my wipers. I was wrong.

Doofy · Nov 20, 2016

Yes sir. That must be why they call it Troubleshooting. It causes so much trouble you just want to shoot it. Don't give up. I've been farting around with vehicles for over 50 years and have never had wiper problems...even with old vacuum operated ones. You might just grab one from the wrecking yard to try.

Tedybear · Nov 21, 2016

Wiper motor is grounded via one of the bolts that secures it to the truck/car frame. It will look like a steel insert in one of the rubber grommets. Make sure you have excellent continunity. (yeah my spelling sucks).

I'd take that fuse back and demand a reality refund! (that always pi&&es me off to see people get taken advantage of).

The other issue might reside in that brown box that houses the relays. It wouldn't be unheard of for one of the relays to fuse the contacts together--or to be smoked/burnt up to the point it acts intermittent. I'd nail a pick and pull yard for the box, it's a cheap swap. First off, I'd take a test light with a bulb. Clip lead to "+" on your battery. Touch the probe end to the metal housing on the wiper motor. It should light up SUPER bright! If not? There's a problem. (might not be the only problem, but grounds can be a PITA for electrical problems)

S-

AttemptingToBeAMechanic · Dec 6, 2016

I went to the junk yard and got a new wiper motor, internal governor, and multi-function switch and the issue still exists. Still at square one; the wiper does not turn off or variably control the motor speed. I also discovered that brush motors are very difficult to get back together. After attempting a number of different techniques of holding the brushes in place against the tension of the springs with paper clips I gave up and decided to use the new motor.

I am assuming that there is a wire somewhere, likely the wire responsible for park (can anyone identify which color this should be from the wiring diagram? Jiggling the wires at the MFS did not change the behavior though), is not making a connection.

I am going to run a toggle switch in-line with the red wire from the fuse box to add park functionality. Even though this partially solves the problem I was never able to figure out how to properly troubleshoot this issue

Ill post back when I get something working.

ericbphoto · Dec 7, 2016

I spent a little time studying the diagram today. Here is what I have figured out. From what you are saying, it sounds like your internal governor module is faulty, unless you can find some wiring shorted to ground somewhere.

ericbphoto · Dec 9, 2016

I took some voltage readings at the motor plug on mine this morning. I verified that in Hi speed, there is 12v going to both Hi and Lo connections on the motor.

I will revise my write-up when I get to work next week.

Sent from my SM-G920V using Tapatalk

Attempting wiper troubleshooting

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