Wipers work and park, but rest at A-pillar between cycles - 94 Ford

[kishy]

Hi friends,
As I continue fighting my way through making my 1994 Crown Vic be ready for its safety inspection, I've arrived at a bizarre problem. I have searched but if this has been posted about before, I do not know the words that were used to describe it at the time.

By all conceivable metrics, the windshield wipers work. However, when they pause in between wipe cycles, they rest at the A-pillar instead of just above the hood. The wipers park correctly when turned off.

I went at this kind of blindly, despite having the shop manual and EVTM, I didn't open them at all for this.
I disassembled everything to get the motor out (what a pain compared to a box). I poked around with what I am going to describe as the reversing switch, the black plastic component that is mounted on the lid of the gear housing. All I was able to do by manipulating it was break the parking function entirely.

I have now picked up the following items from the junkyard:
One 1993 Town Car wiper motor. Application list for this part is 92-94 Ford/Mercury and 90-94 Lincoln.
One 1988 Vic reversing switch. It appears to be the same despite the motor varying.
One 1991 Vic reversing switch. Ditto as above.

I have now done the following:

1. Connected the 93 LTC complete motor. It does not operate at all.
2. Installed one of the junkyard reversing switches on my original motor. This worked identically to how the car was before I monkeyed with it at all (e.g. restored park function but still pauses at pillar)
3. Swapped that out for the other junkyard reversing switch, again on my original motor. This worked 100% correctly for about 10 wipe cycles, but then the wipers shuddered (started/stopped several times in one pass) and then began pausing at the pillar instead of the hood.
4. Swapped that out for the reversing switch off the dead junkyard motor. This once again worked identically to how the car was before I started.

So, having not looked at a manual at all, but having parts-cannoned it somewhat, and having observed it working properly for a short time, it appears to me that the problem is with the reversing switch. Or whatever it's called.

Thoughts, please?
In the meantime I'm going to read the manual and see if I can make sense of it.
edit: the manual does not provide a diagnostic/pinpoint process for this symptom, and after staring at the diagram for a little while, I am not sure why or how it could have this problem without having another problem too.

[gadget73]

I know there was something about the park cam on these breaking. I believe thats the plastic doo-dad within the gearbox that actually pushes on the switch on the side of the motor to make it park and whatever else it does. I don't precisely remember what the symptoms of that breaking though, but it was either stopping at the A pillar, or failure to reverse the motor to pull the blades down below the hood. Maybe pop the motor apart that doesn't work at all and see if that makes sense. I believe you could buy just that piece once upon a time so that tells me it shouldn't be a huge issue to swap.

[kishy]

The switch is operated by guides or channels that are molded onto the plastic gear of the wiper motor. At a glance, the channels didn't seem to be broken, but I will look much closer.

I went to the junkyard to return my dead wiper motor today, but before I did, I gutted it of the plastic gear in case that is the problem. In doing so, I discovered why the motor was seized. The metal shaft which is manufactured into the plastic gear was completely seized in its bore/probably a bushing due to rust. I smacked it with a hammer a handful of times and got it out mostly undestroyed.

I'll stare at it some more tomorrow and see what sense I can make of it.

[kishy]

I compared the gear from the seized 93 LTC motor to the gear in my 94 FCV motor. The channels for manipulating the switch appear the same between them, and appear to be undamaged.

I cracked open one of the switches and studied it a bit. I cleaned everything with electrical contact cleaner and a wire brush. I bent the circular contact disc thing to make tighter contact. Reassembled and tested, found it still pauses at the pillar.

[sly]

Yeah... that's a new one on me. Haven't ever heard of that happening.

[gadget73]

I think its the tiny crank looking thing that pokes into the cover that breaks and causes problems. Looks like yours is fine so not it.

https://charm.li/Ford/1994/Crown%20V...al%20Diagrams/

has the diagram, maybe that will yield a clue.
https://charm.li/Ford/1994/Crown%20V...ration%20Test/

some diag stuff that may or may not be of use.

[kishy]

So, generally I'm all about sensible proper diag, but this is just stupid. None of the information can seem to give me a clear explanation of how the thing works, and since my symptom isn't one of the ones identified for troubleshooting, wrapping my head around this has been quite challenging.

Checked power and ground at the motor and at the module. No faults identified.
Shot in the dark, I reflowed all the solder joints in the control module. No change in behaviour.
Played more musical motor lids (which includes the park/whatever switch). Got symptoms to change, and notably the location of the pause, but never got it to behave properly.
Kind of wondering if the metal shaft is able to freewheel a certain number of degrees inside the plastic gear and maybe that's it. IDK.

Went to another junkyard. Found a newer aftermarket wiper motor in a suitable Town Car. Gladly bought that. Also scooped the module.

Got home, plugged in motor. Verified behaviour was immediately, and consistently correct. Fantastic.
Hacked up my wiper cowl a little to fit the not-quite-right-sized new motor. Assembled all the bits and pieces. Put the wiper arms on. Tested. Worked great.
But after a handful of test cycles, they stopped parking. Instead of pulling down to park, they bumped upwards slightly. Basically when the motor reverses to park, the mechanism isn't sliding backwards and is instead just reversing the rotation of the whole transmission.
I think I've traced this to the sliding plastic thing under the bellcrank (or whatever you call it) which is thankfully serviceable from above, in-vehicle, so I think I can piece together a working solution without ripping it all apart again.

Is it just a fluke that I've had minimal wiper-related concerns with my boxes? This mechanism seems incredibly failure-prone and it isn't really all that different from what the boxes have.

[gadget73]

The wiper system is one of the very few things I've never had to fool with on mine. The linkage isn't original but that was just mechanical wear. I've never had to fool with the electrical side of it.

The motors may have gotten crappier on later ones, there are loads of posts on lincolnsonline about the arms parking part way up or doing various other odd things. Most of the time the solution seemed to be 'replace the motor'.

[Pvt.Hudson]

The main issue I remember from the wipers not parking is the issue with the wind latch which is that plastic piece iirc, but the staying up while paused is probably not a common issue though it would be logical to assume its related in some way to the way it fails when the wipers park upright. Another thing to look at as well is the MFS stalk. Not sure if 92-94 is different then 95+ but worth looking into if its having issues as well.

[kishy]

It is unclear to me if the 90(92)-94 unique motor differs from the later aeros/early whales for functional reasons, or simply due to the connector changing.
The MFS seems to be the same as those years though as the one I took out of a 91MGM recently was part numbered as being for a 97 IIRC.
That switch has now gone into this car because this car's switch is jittery about the different wiper speeds. Fully works, just brushing against it makes the wipers jitter due to breaking contact, so it needs to be gone through.

You are absolutely correct about the windlatch.
I have now fixed my car, and the following conclusions are what I've drawn from the process:

• The wiper module provides voltage to the wiper motor based on the position of the MFS. Therefore, a control problem can be a defect in the module (less likely but it does contain relays which can go bad, think LCM) or the MFS (more likely as it is moving parts that you operate mechanically).
• If your wipers pause in the incorrect location between interval wipes, this is an issue with the interaction between the channels on the motor gear and the switch in the motor lid. I am not aware of information to support how to troubleshoot it e.g. what positions should result in what voltages on what wires, but it is clear that this is where the problem is.
• If your wiper motor does not reverse to attempt parking, this is most likely a control issue, at the module or MFS, not the motor.
• If your wiper motor does reverse to park but the wipers park in the incorrect location, this is an issue with the interaction between the windlatch (sliding plastic part with embedded metal piece) and the bellcrank (unaware of Ford name) - the part on the motor shaft that the wiper transmission attaches to.

My problems were as follows:

• Initially, something about the switch on the motor lid was causing the wipers to pause in the wrong spot - seemingly about 180-degrees away from the correct location, looking at the face of the motor gear. There is no clear indication of what was wrong, but replacing the motor replaced the problem.
• With the new motor, the new problem with parking developed. This was caused by the windlatch "skipping" underneath the bellcrank e.g. the steel spring compressed and allowed the windlatch to slide against the bellcrank rather than being slid laterally in its channel.
• I improved the windlatch problem by doubling up the steel spring - stacked two. However, this made the problem intermittent.
• I fixed the windlatch problem by taking another windlatch from a wiper motor in my parts hoard - actually the older style motor from an 88 Town Car, but the windlatch is the same.

Since the part of the windlatch that hooks against the bellcrank is actually steel embedded in the plastic, it isn't clear to me why it acts so stupid when the plastic wears down, but it definitely does.

This thread at CVN is an asset to understanding some of this: https://www.crownvic.net/ubbthreads/...medium=organic

The windlatch is part 17C518 and the version discussed at CVN is F5AZ-17C518-AA, which sure eyeballs as still being the same thing as the older ones.

Now, as an aside:
Being able to force the wipers to park in a raised position, particularly about midway up the windshield, would be ideal in winter climates especially in a car with remote start. The wipers get packed into an icy mess down at the hood and if they could be held more consistently in the warmth of the windshield defrost, they would work better. So I may end up re-breaking this later, intentionally, but for now I want it to work correctly.

[Tiggie]

Glad you got this one figured out. Been following along but haven't had any helpful tips. Luckily, never any issues with my wipers (yet).

[87gtVIC]

Great persistence and detective work.

[sly]

What a trip. Glad you managed to figure this one out.

[jaywish]

A long frustrating event but maybe this should be a sticky?

[sly]

Nah. It's not a how-to or a common issue. We can leave it for the search engine.