rear wiper operation (run versus park)?

[budwich]

My rear wiper hasn't been functioning well for a while. Previously, during the early summer, it would run "normally" at the various settings but as the summer went along, it basically would move verrrrryyyy sssssllllllooooowwwllllyyy along regardless of the setting. It got to the point where it moved up about 6-12 inches and stop. I could not move it manually. However, it seemed to function in some form to park....ie. moving the switch to off appears to cause it to park normal even if it is stuck going up.
Hence, my question is what is the difference in the park function that appears to operate well while the "forward" motion doesn't. How does the "transmission" determine the park operation requirement versus a normal "back and forth"?
Of course, the other comment is ... wow are wiper motors expensive... :-(
I got the trim off and have inspected wiring along the route... doesn't appear to be any issue although there seems like some "funkiness" with some black tape in places, then gray / brown tape here and there, especially near "anchor points"... maybe someone has been chasing this before (I have only owed this vehicle for 3.5 years).

Anyways, comments on the operation would be appreciated. I am going thru the gm manual to look at the section on troubleshooting. Will get the meter out and check the conditions on the three wires... battery, ground and "pulse ground / control". My original limited understanding was the "pulsed ground" provided speed control, not sure how this can be used for "park command" but maybe solid is park.

 

[budwich]

battery and ground appear to be showing up thru the plug. I am going to try wiring the "speed control pulse" input to ground and see if I get a response.
On a side note, the label on the motor indicates "Valeo" which likely means this has been replaced before.... maybe.

 

[AtlWrk]

You seem to be on the right track but your symptoms lead me to believe either the motor itself is crapping out or the internal gearing/lever mechanism is binding for some reason.

Most of the varieties on rockauto look like they can be disassembled to some extent. You may be able to open, clean and re-grease the gears and levers like we sometimes have to do on the 4wd disconnect actuator. Also inspect for excessive wear or sloppiness in the linkages.

If the motor itself is burnt up (a real possibility if it's stalling half way up the window) then you're probably SOL.

 

[budwich]

providing a ground didn't do much. Now even trying to get it to park is difficult. Looks like motor / control might be done. Is there anything serviceable on the motor / casing.... looks somewhat sealed where it is... I haven't removed it yet.

oops looks like a post "collision"... next step, try and get it off to a bench.

 

[AtlWrk]

I suspect the wiper motor controller will only interpret a fairly specific pulse width and frequency as a valid signal whereas a solid ground would be seen as a fault and ignored. One final electrical test would be to check the control wire (with everything hooked up) with your meter set to AC. If it's truly a PWM signal you should see different values on the line for each setting. The actual numbers don't really matter, just whether or not they change. The fact that the motor is trying to move tells me the control signal is probably not the problem though.

I doubt you'll find individual components to replace on the rear motor (unlike the front wiper motor whose control boards alone can be replaced) so if it can't be fixed you're probably going to have to get a replacement. You may get lucky and just find a big glob of congealed grease jamming something or a feedback scraper making bad contact and confusing the controller but there's only one way to find out.

EDIT: Just noticed Rockauto sells a A-1 Cardone motors that are just remanufactured Valeo motors.

 

[budwich]

thanks for the insight... :-( doesn't sound good. I will try the "ac test" to see if things are happening from the controller / lgm. I agree that's more than likely the motor. I noticed the "reman" on the rockauto site. I might try a "ebay picker" motor but will see where finances go.

 

[C-ya]

Valeo might be OEM. That's what mine is. I can't imagine everyone that replaces theirs gets Valeo as a replacement unless they're the only game in town. Of course, I don't know if mine has been replaced. I took my liftgate panel off to troubleshoot my lock/open-closed sensor and found out why my tag lights didn't work: they were unplugged. So someone had been in there for some reason.

 

[Bruter]

I don't want to highjack the thread, but...

"One final electrical test would be to check the control wire (with everything hooked up) with your meter set to AC."

So it's an AC signal coming from the module...thanks, that explains the difficulty I was having troubleshooting the wiper. I presume that the AC signal is on the green wire?...since the 12 volt is orange and ground is black. You also mentioned that it was a pulse...so no constant electrical power.

 

[Reprise]

I've got this same issue as of a few days ago - thought the motor was going to die on the first sweep...oh, soooo sloooowww...and then went back to park just as pretty as you please. Watching this thread...

 

[Bow_Tied]

I have no direct experience on a GMT for this.

However these symptoms mirror what I experienced on the 2002 Pathfinder that our Envoy replaced. In this case, cold weather exacerbated the issue. I fixed it by completely disassembling it, removing a mild bit of corrosion in the shaft bushing with a bit of emery paper along with removing years of dirt/grime accumulation in this area, likely from winter salt environment, and removed what remained of the dried out white lithium grease. I re-lubed liberally with white grease after cleaning and reassembled and it worked flawlessly in all weather conditions for at least the 1.5 more years we owned it. HTH, YMMV.

EDIT:
I did a write up on another forum for it. Of course it will be different than a GMT wiper, but the mechanical principles are likely to be similar. This one was a worm gear (a spiral/screw that drives a regular gear) which by design cannot be back-driven. This is why you can't force it back down.

 

[Mooseman]

Yep, our Montana van did the same thing, took it apart, cleaned the shaft, lubed it, all good. My TB was also barely moving. Got lazy and just sprayed it with penetrating fluid and helped it in by putting the wiper switch to 3 (on steady) and helping the wiper arm sweep while I sprayed some more. Worked great!

 

[budwich]

thanks for the info. I hope to get the motor off and to a bench tomorrow. Hopefully, a "biopsy" procedure will give me some clues as to where / what I should try before trying the replacement ($$) technique.

One thing about the work so far. I now know what the sprayer doesn't work well. The tube passes thru / near the arm shaft in a "cutout" which compresses the water tube to almost closed. Not sure how it can be setup, but hopefully with a little less compression.

 

[budwich]

OK.... now I need some tips on getting the darn arm off the shaft.... won't budge. Its housing seems to be somewhat fragile (plastic). I tired a bit of pressure with a puller but it is causing the arm housing to start to break / bend... :-( sprayed a bit of penetrating oil into the recess but I don't think its getting into the backside.

 

[budwich]

:-(
well, the pry up on the underside of the arm "worked". The bad news it basically broke away from the shaft leaving the "embedded bushing / knurl nut" still attached to the shaft. I guess I now need a new wiper arm ... :-(

 

[budwich]

so I haven't confirmed the problem yet as I have to rig up my 12v test supply to the internal motor contacts BUT it pretty obvious what the problem actually is. .... :-(
Of course, it is somewhat obvious based on how the wiper operates. Knowing that the controller doesn't what to deal with switching to make the motor go back and forth (and park) as it has enough to do just work the speed control portion of it job, AND looking at the "rotating contact plate", all power to the motor goes thru some portion of the contact plate to get to the two power pins. Hence IF the contact plate has an issue somewhere on its surface, then the motor is likely to have issues completing its "mission". In my case, it is obvious that there is grease all over the contact plate so that the contact wipers may or may not be making any continuity allowing power to ultimately get to the motor. One can see that the contact plate provides the "reversing logic" to switch power from "+" / "grd" to "grd" / "+" so that the wiper may reverse well / park versus forwar operation depending on where and what portion of the contact wiper surface is conducting.

Hopefully my test will confirm that indeed the motor itself runs fine (looking at the worm shaft, it is OK with little or no wear). Of course, now I likely have two problems to over come, sourcing a new arm and getting the previous "arm bushing" off the existing shaft.... sheesh! Not sure if I moved ahead on this in terms of economics.... maybe since a new arm is likely about $100 and a new motor is about $175 (all said and done... taxes, etc). I would have likely had to get a new arm either way as the removal wasn't clean... :-(

 

[budwich]

sooooo.... not sure if the "rat hole" got deeper... :-(
I got power connected up to the motor... didn't move in either direction (ie. switching + and -). I then decided, may be unwisely, to hit the shaft with a good amount of heat from a torch since I still had the issue of removing the "knurl nut" from the shaft. I eventually got the knurl nut off. The "unwisely" part is that I don't know what the makeup of the internals are on the housing and I may have melted things in there. :-(
Anyways, the "good" news, there after, powering the motor readily allows to turn in either direction.... yippie! There is some sort of internal stop that only allows the motor to turn so much. If then relies on the "rotating contact plate" and board "logic" to switch voltage polarity for the reversal.

So I am going to clean contacts on the plate and re-assemble for now and check operation in vehicle... and go from there.
Guess the one question now is did my heating of the shaft end melt any vital components in the shaft mechanical area (ie. plastic bushings, seals)?

 

[budwich]

didn't clean the "contact plate"... the dielectric grease isn't causing any issues (maybe helping). Reconnected the motor and all is working again. Guess the heat of the shaft housing... at the tip where the wiper is suppose to "slide" on and off... ya right... good luck with that. Anyways, now I need to hunt down a replacement rear wiper arm. :-(

 

[Mooseman]

You have the new or old style? I got a replacement old style from the dealer for about $20. New style I don't know.

 

[budwich]

hmmm ... that's a good question. rockauto had no listing. ended up at gmpartsdepot. The problem in canada is limited buying options which means $$ for anything. Not sure I know how to tell "new" versus "old" but hopefully it fits with the blade (which has no clip... but is a "slide in/snap")... otherwise, the "rat hole" continues. Hopefully, the "hot motor" will outlast the arm...

 

[Mooseman]

Yours an '09? Definitely new style. It's seems to be available only from the Stealer, about $58CAD
http://parts.tubmanchev.com/p/Chevr...Arm-REAR-ARM-Wiper-arm/48062380/15232653.html

 

[budwich]

2008... anyways I think we are talking the same as tubman operates gmpartsdepot. I get to pay for shipping ... :-( Probably should have dug deeper into the tubman / gmpartsdepot relationship. I did try to phone them but they don't appear to keep long saturday hours... :-( thanks again for the info / help

 

[Mooseman]

Couldn't you get it from a local dealer? Maybe save the shipping.

 

[C-ya]

The newer style is a covered/enclosed arm. Mine is the bare shaft like the front wipers. Of course, if the new style included changing the design of the fronts, that doesn't help you.

ETA: That's what leaving your screen up, doing a quick errand, and coming back to reply without refreshing does for ya.

 

[Mooseman]

Oh, and if you work for a company, the Gov't or military, they sometimes give the "lower" price rather than retail if they have an account with them. That's the same price they use on their site.

Funny enough, Tubman's is basically just up the street from me, about 20 minutes. Once they were going to charge me retail when I popped out the printout from their site and lowered it. Maybe try that. And I see you're in Kanata. Myers are also pretty good. Surgenor are a bunch of dicks.

 

[budwich]

I talked to tubman and basically their "store price" is almost the same as the "web site" ... ie. item plus shipping. The phone guy didn't seem to want to budge off the price and wasn't sure about cancelling one and buying the other. Wish the gmpartsdepot site would have linked in some form to "local pickup" which I see appears to be an "option" in the "billing receipt" (not offered of course). In this case, its only a couple dollars so I get to save my gas and wait a few days instead...

 

[budwich]

OK... the wiper just showed up at the door...
Small question, the "bushing" that is imbedded in the wiper arm is clearly smooth on the mating surface of the shaft of the motor. The ones that I have seen in the past (ie. fronts and other vehicles) have ridges on them that align on the shaft. I guess there is no "mechanical stops" preventing the arm from rotating on the shaft should it meet some significant resistance. Is this correct? Basically the nut holding the arm onto the shaft provides all the "resistance".

 

[Bow_Tied]

Is the bushing have a slight taper to it? if so, when the arm is tightened it will cinch up. Just guessing based on others I have seen, haven't looked at a GMT version yet.

 

[budwich]

yep, the bushing is tapered so tightening the nut hopefully will provide sufficient "tension" on the surface. The reason for the question is that I have also applied a good amount of anti-seize on it to hopefully prevent a "re-occurence" of the effort to remove the arm is the future. That effort in essence destroyed the bushing / knurl in the arm (breaking the bushing out of the arm). I suspect that a motor replacement may be in my future as I am not sure the "extra heating" that I used to get the old bushing off the motor shaft was healthy for the motor shaft parts in the long term. :-(

 

[Bow_Tied]

I don't think the ant-seize will hurt, most might squish out, but that's ok. The tightening of the joint will create the clamping force needed I think. Taking them apart can be difficult, I found that tapping with a soft-face hammer was got mine apart but I had to still hit it harder than was comfortable.