Wipers don't park

[CountryBumkin]

Now that I'm driving my truck a little more, I want to finally get the Wipers working properly. My truck is not a daily driver, and I never use it if it's raining, so the Wiper issue has been on the back burner.

Background:
I started out wanting to correct what I perceived as weak wipers. The the wipers seemed slow (in both Low and High speeds). You may remember a while ago I posted elsewhere on this complaint asking for others to count the number of swipes per minute so I could compare. Mine was not abnormally slow, but still "weak" when the windshield was somewhat dry.

First I added an extra "ground wire" from wiper motor to body as a bad motor ground is a known problem. That didn't help. So I bought a reman Wiper Motor. When I changed the motor I also replaced the wiper arm mounts/shafts too. So all the linkage is free and moving nicely. Also installed new wiper arms and blades.

But after all that the wiper motor still seemed weak. And it would stop in mid-wipe if the windshield was somewhat dry. It was suggested that the Wiper Switch might be the problem. I ordered one and installed it last week. That did help a lot. So that problem is solved. But I have another.

Current Problem:
The Wipers don't Park.
When I turn them off, they stop in the middle of the window -wherever they are positioned when I turn the knob off.
 
I'm going to go through the troubleshooting steps this weekend. Doing some reading on this issue, it has been stated that a bad "Interval Wiper Governor" may be to blame. Since the Motor and Switch is new, it is unlikely either of these are the problem.

If anyone has any tips or suggestions, let me know. Otherwise I'll post back what I find. Maybe we need a sticky in the How-To section on the best way to diagnose this. it seems to be a fairly common problem.

[Gary Lewis]

This is from the 1981 EVTM, Pages 61 & 62: http://www.garysgaragemahal.com/windshield-wiperwasher.html. As you will see, it is possible for either the switch or the timer to do it, but they would basically have to kill the power they are supposed to pass through on the red wire. But that should be easily tested by probing the red wire just before the motor.




Do you have the shop manual with the referenced section 35-60?  I could put the above screenshots as well as the info from that section on a web page and provide a link in the Resource Links/Electrical section.

[ctubutis]

Diagnosing this exact symptom is in the EVTM circuit description text.

[CountryBumkin]

Gary Lewis wrote

Do you have the shop manual with the referenced section 35-60?  I could put the above screenshots as well as the info from that section on a web page and provide a link in the Resource Links/Electrical section.

I have the manual. I will be using it this weekend.
If I learn anything worth sharing, I'll post it here. Studying circuit now.

[CountryBumkin]

I'm trying to understand the power flow of the Wiper Diagram but I'm having trouble understanding what happens at step 2.

When the wiper knob is turned to "off" is the electronic switch moving in the manner I show below inside the Electronic Switch (switch power from yellow to green)? Meaning instead of power going through ES on circuit 58 (W) does the ES switch power to circuit 28 (BK/PK) at that point?

Still thinking about this: It looks like the Run circuit (red) is always hot. So in low speed power goes through the diode to right side of ES. Then it travels down yellow line to get to the Low Speed terminal on the motor.
Then when switch is turned off, the ES the switch changes (to position as shown) and now connects the motor Low speed terminal (58) to ground through wire 28. Confusing!

[Gary Lewis]

I'm not sure I understand the question, but if I do the answer is "yes".

Let me put it another way. When the switch is on High power is supplied to the motor through the DB/O wire. When the switch is in Lo power is supplied to the motor through the W wire which you have marked yellow. But when the switch is turned to Off power comes down the red wire, and if the wiper is not in Park the arm touches the large contact and sends power out the Bk/Pk wire, up to the switch, and then back down the yellow wire, running the motor until the mechanism reaches Park.

Does that help or hurt?

[CountryBumkin]

Yes. That helps. I think. My head hurts now.

So the "switch" shown in the wiper motor between Run and Park, is actually moving back and forth as the wiper arms move back and forth.


I think there could be a "How The Wipers Work for Dummies" write up from this.

[Gary Lewis]

Yes.

[Gary Lewis]

Note that my previous post was only 4 characters long.

Since we've had this discussion I see a lot more work for the troubleshooting page. See what you think:

It should start with the schematic of wipers without the delay function as that is a bit more simple

I can visualize a pic of the schematic with the flow of power in Lo

The next pic is of the flow of power in Hi

Then a pic of the flow of power in Off, with some narrative as to how that happens

Then introduce the delay module, and do it all over again

What do you think?

[CountryBumkin]

Yes. Would be very helpful. For me its the intermittent wiper system (governor function) that adds the confusion. But if you have the time to do both "power flow diagrams" I think it would be useful.

Or are you asking me to do the diagrams

[Gary Lewis]

I'm on it like white in rice. Stink on skunk.

Y'all may ask why I'm pushing to get things documented, like the voltage-drop test, the TSB's, the Rosewood resto, and now the wiper question. There are two answers: In this case to help a friend with a problem. But in the larger scenario I feel like this site and forum are set to take off - if we have the documentation people need.

Sort of "If you build it they will come", so let's build it! 👌

[Gary Lewis]

No,  I'm volunteering to do the diagrams. Back after while......

[CountryBumkin]

Okay.
I'm starting to understand the circuit...

Looking at the non-interval wiper diagram I see that the Run circuit 63 and Park circuit (28) are only used for Parking. This is much simpler setup.
 

[Gary Lewis]

Yep!

[kr98664]

CountryBumkin wrote

Since the Motor and Switch is new, it is unlikely either of these are the problem.

Oh my, what a knee slapper! Stop it, you're killing me. Have you ever thought of doing stand up? You seem to have the gift.

What I'm getting at is to be careful about assuming new parts are good. I just went through a bit of trouble with my car showing higher than normal coolant temps. Turns out I had both a bad thermostat causing the temperature to run slightly high AND a bad sensor causing the gauge to show higher than actual. Here's the bad part. A new thermostat and temp sender were both bad. Each helped a little, but not enough.

Talk about a head scratcher. Had to delve deep into troubleshooting to prove both new parts were bad. And these were OEM, too! The final fix was replacing both parts with a different brand.

I wouldn't put much faith in a reman wiper motor. Seems like they get fresh brushes and paint, and that's it. I've had my wipers refuse to park and the problem was a little switch in the gearbox portion. I've cleaned up the contacts and would be good for a couple of years.

Karl

[CountryBumkin]

kr98664 wrote

Oh my, what a knee slapper! Stop it, you're killing me. Have you ever thought of doing stand up? You seem to have the gift.
...
What I'm getting at is to be careful about assuming new parts are good.
I wouldn't put much faith in a reman wiper motor. Seems like they get fresh brushes and paint, and that's it. I've had my wipers refuse to park and the problem was a little switch in the gearbox portion. I've cleaned up the contacts and would be good for a couple of years.

Karl

 Yeah, we have all been burned by making the "new is good" assumption.

So, I'm doing a little thinking and studying on this now - this weekend I'll take out the Fluke meter and see what's up. I'm hoping the contacts are just dirty.

[Gary Lewis]

I should get done this afternoon with the troubleshooting section here: http://www.garysgaragemahal.com/windshield-wipers.html.  The how-to will have to wait.

(Fluke?  I wish!  )

[CountryBumkin]

Gary Lewis wrote

(Fluke?  I wish!  )

 
Trade ya for the Lift

[Gary Lewis]

Ok, see what you think now.  And, that's now listed in the resources.  

[Gary Lewis]

Not sure that'd be a good swap - lift for a Fluke.  I have several old DVM's that get the job done, so I guess I'll pass.  But thanks for the offer?