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Testing a wiper motor

5385 Views 15 Replies 7 Participants Last post by  Alfajay
I have a '69 GTV 1750, US model 105.51 that I am reassembling. I have refurbished the windshield wiper mechanism, and as a result I have access to the wiper motor. It is clean and appears in good shape, but I get no response when the battery is connected, the key is on, and the wiper lever is activated. I'm not an expert at electricals (or anything else for that matter), though I did manage to bench test my heater fan motor after restoring it. I wonder if someone could explain the process for testing whether the windshield wiper motor works. I'd like to make sure before I put the wiper mechanism back in, and reinstall the cowl and front windshield. Advice would be much appreciated.

Thanks. Tim
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Do you have the correct 3-wire wiper motor?

If so, the white wire connects to the white/black wire to the foot operated washer switch, the green wire connects to the blue wire leading to the wiper switch, and the red wire connects to the blue/black wire which also leads to the wiper switch.

Yours should have a two-speed motor so what the above connections leads me to believe (and I'm sure someone can correct my poor electrical knowledge) is that the motor grounds to the body through the mounts. Try hooking the positive wire to either the red or green wire and the negative to the mounting tab of the motor.

I haven't gotten to this point myself so you are, basically, my guinea pig.;)
Thanks, Brad. I'm pretty sure I have the three wire motor. I'll pull it and check this evening, and give your instructions try. I'll report back. Thanks. Tim

PS: Disclaimer noted. I'll keep a fire extinguisher handy.
I'm pretty sure I have the three wire motor. I'll pull it and check this evening, and give your instructions try. I'll report back.
Shadetree offers good advice on the wiring.

Actually, if the motor is currently installed and wired up, I wouldn't pull it right away. First thing I would do would be to use one of those pointy-tipped testers (see photo below) to check if there is power to those three wires. As I recall, the red wire should have power all the time, one of the others will have power for high speed operation, and all three should be hot for low speed operation.

If the red wire doesn't have power, then the motor may be OK, and the problem in the fuse/switch/wiring. Of course, another possibility is that both the motor and the fuse/switch/wiring are bad.:D

Is the wiring harness plugged into the washer pump pedal? It's gotta be plugged in for the motor to work.
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On that note - do the foot pumps fail ? and if so are the reproduction foot pump units of good quality?
the case acts as a ground, so if you are bench testing the motor clip your negative to the case
On a slightly related note I have a question about the washer bag. It has a pump/motor in a kangaroo pouch on its exterior. My foot pump has no electrical connections built in. Now the question: Shall I 1) not use the foot device and provide a push button for the bag/motor, 2) Use the foot pump and manually turn on the wipers or 3) have the little electrical motor feed the foot pump???? I am not concerned with originality in this case and I have no Idea which parts originally came with the car...a 1969 1750 GTV that was assembled by the P.O. with a bit of this and a bit of that.
On that note - do the foot pumps fail ? and if so are the reproduction foot pump units of good quality?
Well I guess everything fails, so the answer to your question is "sure".

The foot pumps have two components, with different liklihoods of failure:

- A mechanical pump that pushes some wiper fluid through the tubing and out the nozzles. The bellows in this component will dry out and crack with age. It's rare to find an original pump that still moves fluid.

- An electrical switch that turns on the wipers at high speed as long as the pedal is depressed. One set of contacts (normally open) is closed by stepping on the pedal, and energizes the high speed wire. The second set of contacts (normally closed) interrupts the low speed connection - if the wipers are already running on low speed when you step on the pedal, this ensures that the motor runs at high speed for a couple of swipes. These electrical switches are fairly reliable.

I know nothing about the repro units, though I see that Centerline carries them. I just use the electrical function on my used pumps, and don't bother hooking up the fluid lines. Then too, it seldom rains here.

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Thanks all for the help guys. I'll get to it this weekend and see what I've got. Jay, that'll give me time to get one of those pointy tipped things. Probably should have gotten one along time ago anyway. Tim
windshield washer problem a wash

Thanks all for the help. I just found the P.O. had given me 2 pumps. One has all the electical spades and so I'll use it. The other must have come from another model or another car altogether.
OK, here's an update with a new question.

The Question: Is there someplace that reconditions or rebuilds these wiper motors?

The update: I confirmed I have the three wire motor. I tested it according to Brad's directions and got no movement. Not trusting myself, I took it to an local auto electric shop. They tested it and got nothing. So, now I need to move to the next step.

I've checked out the various discussion about using a wiper motor from a BMW E21. Is that the only option or is there someplace that will recondition or rebuild these things. I'm thinking of a place like Palo Alto Speedometer but for wiper motors. The auto electric shop that tested the motor can't do it and couldn't recommend anyone. I checked both electric motor rebuild companies in my area and neither will work on motors from cars. Though I doubt the car will ever see rain, I still don't want to reassemble it without functioning wipers. And even the best intentions on driving conditions can be thwarted by the great Pacific Northwest rain.

I'd really appreciate any help or suggestions. Given that the old one doesn't work, I do plan on taking it apart to see if I can do anything to repair it. Nothing to loose.

Thanks. Tim
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I saw those threads about the wiper motor from a BMW E21 fitting an Alfa, but didn't memorize them. For what year Alfas did people report successful BMW --> Alfa transplants? Alfa changed the design of the wiper motor/gearbox over the course of the 105/115 era - your '69 GT has a different motor-gearbox than an 80's spider. So make sure the BMW E21 motor will fit a '69 before assuming that's your solution.

If you do take your motor apart, here's two areas that I have found to be failure-prone:
- The contacts on the gear that implement the "park" mechanism. Eventually the contacts wear down, and fail to make a connection. If that's your problem, and if you can live without park, you could bypass those contacts.
- The brushes eventually wear down. And the cages that hold the brushes are very flimsey.
For what year Alfas did people report successful BMW --> Alfa transplants?
The thread in question was about a 69 GTV but the transplant took place in a 74.

Here's the thread on installing a 4-wire motor in a 3-wire car.

Hope this helps.
Jay and Brad: Thanks very much, both of you. The help is much appreciated.

...the transplant took place in a 74...Here's the thread on installing a 4-wire motor in a 3-wire car.
ShadeTree: Thanks for searching for that thread, and posting the link. I read it again and was reminded that axeman74 had posted pictures of the '74 Alfa and BMW wiper motor/gearbox assemblies (post #6). I also saw that I contributed to the thread (post #5 & 7), explaining the physical differences between '60's and '70's Alfa ww motor/gearboxes, and as such, between '60's Alfa and BMW E21 parts.

On early 105's - the cars whose wipers move like a bird flapping its wings - the axis of the motor isn't parallel to the mounting plane (see first photo below). From the photos posted by axeman74 on that 2006 thread, the later motor's axis appears to be parallel to the mounting plane (see second photo below). So check this on your '69 before committing to a BMW motor. In my mind, this problem is much larger than whether the motor has 3 or 4 wires.

If you really want to do some experimenting, you might try to mate the E21 motor to your '69 Alfa gearbox. My concern about this strategy is that the worm gear on the BMW armature might have a different pattern since it is designed to drive at 90 degrees, while the early Alfa has a non-right angle between the motor axis and the gearbox output shaft.


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