Hi All,

After 27 years, my rear wiper stopped working, on both intermittent and regular positions.

I checked the fuse (#14), all good there.

Next step is to see if I get current to the motor, so I removed the tail gate panel, everything is very clean, I mean, I was surprise, it looks new :)

Before I remove the whole block, I noticed three wire plugs to the motor:

1) White-Yellow
2) Orange
3) Black

When testing this, should I expect to see 12V between Black and White/Yellow as well as Black and Orange? I guess, depending on what I select, like, intermittent or regular wiping.

If I see DC in there, what would be the next step to take?

The relay? How do I know if it is working?

Thank you!
Alex

Looking at the 940 wiring diagrams for you, at the tailgate:
o Black is to chassis ground behind the left taillight (uses the same ground screw as the taillight assembly).
o Yellow-white is +12V for the wiper motor from the wiper relay (relay socket pin 6, relay pin "S"), controlled by the wiper switch.
o Orange is +12V for the wiper motor park function. It's the same power the relay and wiper switches get from fuse 14 when the ignition is on (socket pin 4, relay pin "15").

Verify that the black wire provides ground (screws on the aluminum tailgate opening threshold are a convenient test point). If you don't see power back at the orange wire in the tailgate and everything else on fuse 14 is working (like the radio) then it's a wiring issue. Unlike the 140/240 wagons, the tailgate wiring at the hinge area in 700/900 wagons is generally not a trouble spot. Double check that the wiper wiring inside the tailgate hasn't somehow been chafed by the wiper linkage.

My main initial suspect would be the rear wiper relay (back row, rightmost in the tray), although I don't recall that I've had one go yet. I'd be able to swap in the same relay from my other wagon, but you likely don't have that luxury. For you, diagnosis will be a bit trickier. Next suspect after that would be the wiper switch. My third would be the motor. That's the order I would normallly want to do for diagnosis, but ease of access to connectors to isolate the fault is a consideration in where to start.

As you've got the tailgate open, you could try jumping 12 volts from the orange wire to make sure the motor runs. Any chance you can get a U-shaped paper clip into the back of either connector half to jump power from the orange wire pin to the yellow-white wire pin? If not then you could open the connector and use test leads to provide ground to the black pin and power to the yellow-white pin to run the motor. Once the wiper moves a bit you can reconnect it and the wiper should then finish its cycle and park. Easier though, once you've got the relay out, would be to jumper pin 4 to pin 6 in the relay socket to accomplish the same thing and force the wiper to run.

For the sake of simplicity and laziness in your case, I'd probably next think about opening up the wiper switch console and verifying the switch, unless the connector there is too buried for easy access (I forget at the moment). You want to see continuity between switch connector pin 1 (orange) and pin 4 (yellow) when the wiper switch is on (to the right). With the switch connector open, a jumper between orange and yellow there should now run the wiper if the switch is bad. Alternatively you could check the switch at the relay tray socket (continuity between socket pin 4 and socket pin 5 when the wiper switch is on, corresponding to relay pins "15" and "31b"). If it's the switch, try a spray contact cleaner.

After that it's time to diagnose at the relay (back row, righmost). For access you'll want the storage shelf out and the tray unclipped and slid forward. Verify relay socket pin 1 (corresponding to "31" on the relay) is chassis ground (black wire on the cigarette lighter is a convenient ground test point). Verify near zero Ohms between relay pins "31b" and "J", otherwise bad internal contacts. If there's an open circuit between relay pins "31" and "86" or between pins "15" and "J" then it could be a fried relay (check +/- both ways in case a diode is in the way).

Although these relays are not known as repairable, next thing I'd do would be to open it up and try re-flowing the main solder joints, being all those solder joints connected to pins "15", "31b" and "S". Nothing to lose by trying. Please post back if that fixes it.

After that it would be time to get a bit more creative in testing, such as carefully wire wrapping test leads to relay pins and re-inserting the relay so you could use a meter to see what's going on and simulate the switch in various positions. Or else go seek another relay (new or good used).

For relays, the front wiper relay lives next to it. It's a similar, but not an identical relay and setup. The diagrams show the relay basic pin functions and socket pin numbering are similar. I've not done this, but there's a chance if you can put the front relay in the rear relay socket that the main wiper on/off function might work, which would prove it's the rear wiper relay. A bit risky perhaps so I'm not advising you try, but knowing me I'd probably try it, maybe after doing a bit more verification in the wiring diagrams and looking at the relays themselves.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Dave and all,

I just disassembled the whole motor set (motor + wiper arm) and measured with my tester. There is 12V with both wires, I also checked the intermittence and it gives me 12V every few secs.

https://postimg.cc/hQb0ZyDV

Can a motor die like that? It seems so strange to me, as it did not slow down or nothing, it worked perfectly until the day before.

I see resistors, could they be the culprit?

I see that the motor is sealed with rivets, so I guess I cannot open it, at least not easily.

Thoughts?

Thank you!
Alex

I've not had or recall hearing here about one of these rear wiper motor assemblies failing. If it was a 240 front wiper motor then I'd have all kinds of ideas as they were indeed troublesome, also repairable. Could be something like the copper contact fingers in the gearcase for the park and wipe function giving up. If the case is rivetted then disassembly for inspection and possible repair is going to be difficult. I'm not sure I'd even bother, just start shopping around for a good used one.

That's one weird looking resistor, looks more like a diode. Oh, wait, the wiring diagram indeed shows a protective diode in the motor on the "31b" terminal. That could easily be the problem. You'd have to take one end out of circuit to test it for directional resistance to see if it's failed (in the park position the contact in the motor is parallel to it and will give near zero resistance if measured in circuit). Shouldn't be too hard to replace it, either soldered (careful with the heat) or using a crimp ferrel. Just find a 12V rated diode of suitably high watts (which should be the number before the W I see, a higher wattage would be okay too) and there's a good chance you might be able to repair it. [edit: ignore my previous comments about the possibility of it being a capacitor]

Only problems I've had with those wipers is the spring in the arms getting weaker over time and in one wagon the nut on the threaded aluminum collar through the gate continually works loose so the wiper wobbles. I'm thinking it initially became slightly loose and over time the threads have become damaged. I'm just about ready to JB Weld it in place next time I've got the panel off. 13" wiper blades are also not that easy to find so I just cut down old front wiper blades and insert them in the holder.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Dave,

You probably missed my second post of today, I tested the motor, and it works perfectly.

Please read the rest in my previous post.

Thank you!

Hi Alex,

How much hassle is it to reinstall and retry?
Maybe you have a connector issue ?

Bill

Hi folks,

I cleaned and re-assembled everything, and what happens is that when I tight the nut holding the wiper arm to the motor and start the motor, I can hear the impulse of the motor, but it is like the arm cannot move.

The motor works fine if I disconnect the arm.
I cannot understand what prevents the arm to make its movement, everything looks good, including the splines.

I wonder, it this supposed to have this play, or should it be pushed inside?

https://postimg.cc/G9kNsswB

More images, the arm looks absolutely fine, but clearly, something mechanic happens when the arm is in place, preventing the natural movement it is supposed to make.

https://postimg.cc/3dYqjJYt

https://postimg.cc/N27zhZ78

Thoughts?

Thank you!

That is perplexing. I was going to ask if the wiper blade was stuck to the glass, but you're way past that. Would you say the rear wiper has been lightly or heavily used for its age, meaning is it more likely badly worn or seized from lack of use?

Sounds like something is binding or locking up somewhere, but only under some kind of lateral or in/out tension? If the motor runs easily it would seemingly have something to do with the linkage. With one end or the other disconnected you'd think you'd be able to duplicate a lack of movement at same odd angle.

The weak point in the rear wiper desaign in my experience is the aluminum casting through the gate. Yours looks in better shape than the one I last had out. I presume when loose off the car that the aluminum casting can be easily turned on the shaft by hand both when pulled out and especially when pushed in as if under wiper arm tension?

You've likely just come out of winter driving where salty roads spray coats the tailgate. The aluminum can easily get a bit corroded, especially if the lube becomes dry, and could in theory act like it's seized. There should be a circlip near the splines that holds the shaft in the casting. Can you remove it so you can slide out the spline for inspection and lubing? I'm not sure if there's a pressed in brass or steel bushing, hopefully not just aluminum.

With the wiper and linkage installed without being fastened to the motor, the linkage can be moved by hand such that the wiper turns? The linkage pivots should be fairly forgiving even if fairly worn as long as they're lubed with a bit of grease.




--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Dave,

That shaft does not move by hand, I removed the circlip and the washer, but the shaft does not want to come out.

I will try to find a way, but it clearly as it is now, seems to be seized.

Aha, now you're onto it! If you can just get that spline out for a cleaning, polishing and lubing then this should be totally repairable. A wire rifle brush (thin bottle brush) would be useful for cleaning the bore of the bushing.

Multiple applications of a good penetrating oil like PB Blaster over a few days may get through enough of the corrosion to be able to turn the spline back and forth a bit and slowly work it out. Maybe apply a bit of heat a few times to help break the bond and also wick in. I doubt there's anything inside to melt and burn other than trace lubricant, maybe a slim chance of a fibre washer on the back end of the spline.

Failing that, my next step would be thinking about trying to dissolve some of the aluminum corrosion that may well be behind this, such as at the back of the aluminum casting. In order to avoid damage to the exterior surface and threads, if you can lay your hands on what's called aluminum jelly (an acidic form of petroleum jelly) and put a small bead around both ends of the spline at the casting then that may help dissolve it enough to get it moving. You may have to leave it for quite some time and again apply heat to get it to wick in. Start by using a spray solvent, like contact cleaner, to remove traces of the penetrating oil.

I'm looking forward to your success as this could easily happen to me as both of my 940 wagons get highway use in the wet. The back ends are always getting coated in road spray with dirt and even salt. Mind you, I'm always using them so hopefully they don't get a chance to seize up like yours.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi All,

Just a quick update:

I tried with any possible means to remove that shaft, but without success.

PB Blaster for multiple days, even torch, but no way.
So, I ordered a used arm at Voluparts and I am waiting for it to be delivered.

When I get the arm, I want to remove the shaft (even if it should be working), lube it and put some anti--seize (Permatex).

Question for you: I do not see how to lube and put Permatex, I mean, once I have cleaned everything, shouldn't Permatex the only thing I need?

Thank you,
Alex

In addition to the good advice from Bill and Spooky Jay, Permatex anti-seize does have lubricant properties and could be used on the back side, but better to use something on the shaft itself designed for the job, like a standard spray moly or lithium lubricant (for hinges) and use the rear wiper more occasionally than you presumably have in the past to keep corrosion from building up at the aluminum-steel contact points that is presumably what allowed the shaft to seize that bad in the first place. Going for a good used one is a sensible move. You've now got nothing to lose with the old one and get carried away with heat (like Bill's MAPP suggestion, much better than a propane torch as it's a faster heat for quicker expansion to break a bond) or getting more vicious with it in a vise to see what it takes to break through the corrosion and get the shaft to move with the least amount of damage. I'm now using you as my guinea pig in case this ever happens to me.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Dave,

Getting carried away? That's a rash statement.
He's got a frozen shaft, and I wish he was next door.

I want to change my recommendation for lubing the shaft since
maybe there's Oilite bushings in the housing, then Spook would
be spot on. If they cut corners and its aluminum against a steel
shaft I'll stick with nickel anti-seize.
I'd be surprised if Oilite bushings froze up solid.

How are your LED headlights? How much current do they draw?
What's your results? Are you convinced that they blow away halogens?

Bill

Bill, my LED head light trial is continuing in both 940s under varying road conditions. I'm getting a few too many lights flashed at us in both cars, especially at night, but also during the day. Our large almost one square foot reflectors are seemingly way too big for LEDs making people think our high beams are always on whether or not they're being blinded. Putting almost any decent LED 9004-sized bulb in an oversized reflector designed to make the most out of that inferior 9004 bulb design makes them way to efficient. I've adjusting the beams lower than normal in one car and that may have helped a bit. It's also the car most frequently used on unlit roads at night. I hope to have more to say on this later in the way of a proper review and what to expect and watch out for when trying those Auxito LEDs or something similar.

Measuring amps is still not on my do-list. The number is unimportant for my purposes at the moment. I'm not out to compare bulbs or brands, only suitability in actual use. My clamp meter only does AC amps anyway.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Dave,

Adjust the headlights so they are aiming at the road and not at the oncoming traffic. If you get lots of flashes then you need to readjust.

It's easy to measure current at the headlight fuses, and would help me compare your Auxito headlight with the others I've tested. I'm guessing you will find
about 2 DC amps for those lamps, Use your VOM which should handle 10 amps.

You can take a dead ATC fuse and Dremel the top around the metal legs, and solder
wires to it to make a handy test plug to measure current in ATC fused circuits.
Perfect to measure the headlights. That will be lower than the 10 Amp limit in
most VOM's.

Over ten amps you need the HF current tester or an analog meter with that same
plug made from a dead ATC fuse.
Get a 0-50 DC Amp analog meter with the shunt for $15 at Ebay.
Then you can safely survey your fuel pumps that normally draw 10.5A Total
Then ask how some people were blowing 25 Amp fuses and then 30 amp fuses
for the Fuel? Those same people found their fuel relay sockets toasted.

Checking current in a fused circuit is a good diagnostic tool.

Bill

Hi Alex,

Did you secure the aluminum bracket in a vise, and find the bracket arm turns
but not the shaft? If so the shaft got free where it was secured on the arm.
Since you didn't blow a fuse the arm might be toast where the shaft peans into it?

Other wise the steel shaft is corroded to the aluminum casting.

Did you use propane gas? If so use MAPP gas, its hotter.
Try again while you're waiting for the new arm.
Did you try heat (MAPP Gas) and then punching the end of the shaft to break it free. (With a nut on the thread of course)
Get the heat on the Threaded end of the shaft then do the candle.
Then try to heat the arm end of the shaft if you can see where it's peaned into the lever arm , give more heat and pressure on the arm to break the shaft free.

Hopefully they include the bracket.

In any case with Steel shaft into aluminum I'd Use a thin film of nickel
based anti seize, that's what it's made for.

Good luck, Bill

Dear Metallo,

Hope you're well and stay so. Anti-seize is designed for use on threaded fasteners. It keeps water from getting at the threads. That slows / prevents formation of a metal-to-metal corrosion bond.

Used on a tightly-fit shaft, anti-seize is likely "to gum" when temperatures fall. That will increase the load on the wiper motor.

To keep the wiper shaft from seizing, lubricate it with a light-weight machine oil, of the sort you'd use on a door hinge, that squeaks. Even better would be a Teflon-based lubricant, which will provide lubricity until temps are -100°F, at least.

Hope this helps.

Yours faithfully,

Spook

Alex,

If you can't repair the wiper assembly here's a Plan B.

https://www.ebay.com/itm/196030896808

Bill

Bill,

The motor has no issues at all, the problem is the arm shaft, I am trying to remove it, but so far no success.

I took the circlip off as well as the washer, but I am having issue to pull out the shaft, which I think is seized.

Alex

OK Alex,

I see your image *134646 shows the pot metal support for the wiper blade shaft
frozen to the steel shaft.

1. Mystery oil at either end of the pot metal/aluminum support and a long soak.

2. The candle trick:
Get some heat on the steel shaft & pot metal bracket, then push an ordinary taper candle, stolen from your wife, so that the candle wax wicks onto
the hot steel wiper shaft at both ends.

Then you can brace the support and with a nut on the end of the wiper shaft
Tap the shaft back against the braced potmetal/aluminum casting support.
I had good luck with this method before.

If it doesn't come out easy try heating, and the candle again.

Once it's apart you can dress the shaft and bore and lube with anti-seize.

Could you have removed the clip and tapped the shaft back before you removed
the bracket from the tailgate? If so, that might have freed the shaft?

Good luck, Bill

Hi Alex,

Were you able to get a look at the motor itself?
That's what I would want to see.
Your earlier photo looked like there may have been peened studs
holding the cover?
Are there brushes to replace in there?
What do you see for voltage at the motor when it runs?

Make sure the arm ball joint is free.

I just went out to my 940 and measured rear wiper about 3 amps current draw with
a 0-50 A analog meter, and about 2.5-2.7 A with the cheapo HF VOM I keep in
the glove box. Measure at Fuse 14 socket (fuse out) and the positive is up top.
See what you draw for current, quick and easy to do.
Remember to set your meter and probes for 10 DC Amps.

Bill

Oh, sorry, went straight to the link in my email and later didn't refresh my browser to catch all your posts, also editing the post a few times. I'm thinking maybe pitted/worn contacts in the gearcase if it started working on its own again. Has it had a lot of intermmitent operation over the years?

That red arrow is pointing to what I think is just a bushing stampedin the gearcase plate. You shouldn't need to remove it, maybe just a drop of 3-in-1 oil on it when you're done. You're on your own trying to carefully pinch those rivet heads to try opening the gearcase. Be careful to open it slowly to figure out the assembly. Mark everything for later realignment. First time I took a 240 gearcase apart it took a fair few attempts to get it back together properly as I wasn't looking when it all came apart.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Again,

I took another step: plugged in the motor without the wiper arm, everything works perfectly, both continuous and intermittent wiping.

So the motor is not seized.

It works now with the same wiring, why not before when in place?

I'd like to open the motor so that I can check it and lubricate.

Do you know how to open it?

https://postimg.cc/svHDRzgx

Where you see the red arrow, there is a central round lock pin that seems to keep in place the cover, I have never seen that type before and I have no clue how to remove it.

Thank you,
Alex

BTW With 700/900 tailgates be extra, extra careful with the plastic mounting tabs at the bottom of the panel. They can easily break during handling, removal and especially during re-installation. There's an aftermarket set of metal tabs available that clip over the remaining stud in case you break them. I once specifically warned a glass shop about this and they went ahead and broke them, grrr.
--
Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now

Hi Alex,

You're off to a good start for the troubleshooting.
You need to find connector C22 which is on the drivers side opening on the top feeding the tail gate wiper.
Look for 12V DC between the Black and Orange, and the Black and Yellow/White wires. That will determine if the fault is back at the switch or a fault with the harness or rear wiper.

My hunch is the ground lead is open, the ground "31/11" is up there at the top drivers side of the tailgate opening. Make sure it's a good connection.

Post back with your findings.

Good luck, Bill