Wiper only doing half rotations. HELP! (1 Viewer)

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Oct 11, 2024
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australia
Purchased an 80. I’ve been having problems with getting this wiper to function correctly for my roadworthy certificate in Australia. It seems to only be doing half the action per time. I’ve tried 3 motors and all do the same thing. I’ve attached a video that I have uploaded to YouTube.

 
That motor action looks correct. The linkage translates that into a reciprocating motion.
 
That motor action looks correct. The linkage translates that into a reciprocating motion.
Maybe I worded it wrong, but in the video you can see the motor stops, where as the wiper in the background continues working. I tried this motor on the right hand barn door and it works fine. I’m thinking a relay problem?
 
I'm lost. Does the motor work or not? The gearbox action has a dwell in it.
 
I'm lost. Does the motor work or not? The gearbox action has a dwell in it.
The motor works, but only on the right hand door. In the left hand door (in the video), it has a delay, if you compare it to the wiper action in the background.
 
OK, but you're describing two completely different things. The motor, actually the gearbox, action isn't the wiper arm action, there is a linkage between them.

Is there an access panel on the inside of the door that allows you to observe the mechanism that works, as it's moving?
 
OK, but you're describing two completely different things. The motor, actually the gearbox, action isn't the wiper arm action, there is a linkage between them.

Is there an access panel on the inside of the door that allows you to observe the mechanism that works, as it's moving?
Yep the linkage works fine. The motor doesn’t do a full rotation like the right hand side. The wiper arm will go up and stop and not come back down, until the next cycle. You’ll see the right hand wiper continues to move when the left hand motor has already stopped.
 
As far as I can remember, the motor rotates constantly, once the current is applied. The gearbox has a dwell in its cycle, so that the linkage can coast past center and not bind, on the way back. This is how the one direction motor rotation is converted to reciprocating motion of the wiper arm.

You should be able to see this, if you can observe the linkage action.
 
Maybe I worded it wrong, but in the video you can see the motor stops, where as the wiper in the background continues working. I tried this motor on the right hand barn door and it works fine. I’m thinking a relay problem?
I think you’re on the right track. It almost seems like there’s a malfunctioning delay circuit involved. Do the rear doors have a delay option on them? Like you say, the motor goes 180°, stops and then another 180°, and stops. For proper delay action, the motor should make one complete 360 degree revolution and stop.
 
I think you’re on the right track. It almost seems like there’s a malfunctioning delay circuit involved. Do the rear doors have a delay option on them? Like you say, the motor goes 180°, stops and then another 180°, and stops. For proper delay action, the motor should make one complete 360 degree revolution and stop.
There is an intermittent option. Even that only goes 180. The wiper goes up and stops. It doesn’t go back down until the next cycle 5 seconds later.

You can see in the video, the right hand barn door continues a full cycle still.
 
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That’s the correct term – intermittent. It would seem that the wiper mechanics are working fine. I think you’re going to need the electronics diagrams - schematics. You’ll need the correct specs and year for your rig. I don’t know if there’s a wiper control unit box or its location or if that shares the front intermittent wiper circuitry. I assume The front wipers are working fine. The correct factory service manual (FSM) Will be your friend on this. I believe there’s a digital copy you can download from this site.
 
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When you find the relays, if they are the same, swap connectors to see if your rh does it.
Or you could just run wires from Lh connector to the rh and see if rh goes like your Lh.

Before you buy parts.
 
My 97 80 series had a similar issue on the rear wiper.
On the wiper motor remove the cover where the wires connect. Inside is a flat disk with electrical contacts that rotates when the motor is on (on, off, on, off, etc or on all the time, etc). There are two or three copper fingers that ride against the disk when the wiper is on (intermittent delay, and constant rotation Etc). This rotating disk is how the motor will stop and start based on the the dash switch. In some cases the rotating disk will energize the wiper delay relay or the like.

In my case. My rear wiper would not complete its cycle. Turn it on, the wiper would partially move through it's cycle. Turn it off and the wiper would return to the home position. It is possible the disk or finger contacts have worn out.... However, it is more likely the contacts need to be cleaned. In my case, the grease used to lubricate the worm gear and rotating contact disk goes bad. Gets gummy/sticky and prevents/limits electrical contact. Clean every thing, remove the old grease, clean the disk (brass contacts) and fingers with a mild scotch bright pad or 600grit wet/dry sand paper and re-grease with Toyota wax/grease. I use Super-Lube with Teflon (goggle it).
 
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