Testing Windshield Wiper Motors
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I am posting this in a new thread so it can be added to the FAQ section. It is instructions for testing the wiper motor out of the vehicle. I made up some jumper wires with spade terminals and/or alligator clips to make the hookups easier. Watch out for the rotating arm when you make the connections, it can wind the wires up pretty quickly....:).. The 2 speed wipers for the '67-'72 trucks are about half way down.
-------------------------------------------------------- Article from Ray’s Chevy Restoration Site http://rmcavoy.freeshell.org/electrical.html Q - How is the windshield wiper motor wired ? How can the circuit be tested ? A - Single speed wipers were base equipment on most early 60's GM vehicles. They have one (fused) power wire that is connected directly to the wiper motor. This wire is live whenever the ignition switch is on. A second wire connects the motor to the switch on the dash. When the wiper switch is turned on, it completes the circuit to ground (the dash). The single speed motor can be tested using the following procedure: * Use a test light (or voltmeter) to check for power at the wiper motor. Do this with the ignition switch on (wiper switch can be on or off). No power at the motor is an indication of a bad fuse and/or wiring. * Next, (with the ign switch still on) connect a jumper wire from the switch terminal on the motor to ground. That should cause the motor to run. If it doesn't then the motor is probably faulty. * Finally, the wiper switch can be tested with an ohmmeter or continuity tester. Also make sure that paint or corrosion isn't keeping the switch housing from properly grounding to the dash. Two speed wipers with washers were available as optional equipment on early 60's GM vehicles. They became standard equipment in 1965 or 1966. This system still uses the same basic wiring principles as the single speed wipers. There is still a power wire that feeds the wiper motor whenever the ignition switch is on. Except now there are three wires going to the switch. The switch grounds one wire for high speed operation. Two wires are grounded for low speed operation. The third wire grounds the washer solenoid to activate the washers. Note that many '75 and later vehicles used a small electric washer fluid pump mounted to the reservoir instead of the older wiper motor driven pump. 2-speed wiper motors - This is the '67-'72 wiper motor There are also 3 types of 2-speed wiper motors. One is a non-depressed park motor that is easily identified by its rectangular motor case. Another is a depressed park motor that has a round motor case attached to the gearbox at an angle. The third is a permanent magnet motor that has sort of a rounded 6-sided motor case. The diagram below illustrates the non-depressed park (rectangular case) motor. The washer has been omitted for clarity. The depressed park (round case) motor uses the same wiring concept except the terminals on the motor are arranged in a different order (3 Low, 2 Power, and 1 High). The permanent magnet motor (used primarily on 1978 & newer GM pick-up trucks) has separate terminals for the park switch and therefore uses a different wiring setup. Testing the wiper motor independent of the switch: (in or out of the vehicle) The depressed park and non-depressed park 2-speed wiper motors can be bench tested independent of the dash switch by making the following connections: * Ground the wiper motor housing. * Connect a jumper wire from a +12V source to the #2 (Power) terminal on the wiper motor. It's the bottom terminal on the rectangular motor or the middle terminal on the round motor. * Connect a jumper wire from ground to the #1 (High) terminal on the wiper motor. It's the middle terminal on the rectangular motor or the bottom terminal on the round motor. This should operate the motor at high speed. * Leaving the above connections in place, add an additional jumper wire between the #1 (High) and #3 (Low) terminal. #3 is the top terminal on both the rectangular and round motors. This should operate the motor at low speed. * On the rectangular case motor, leave the jumper between terminals #1 and #3 but disconnect it from ground. That should cause the motor to run (at low speed) until it reaches its park position at which point it should stop. * On the round case motor, leave terminal #3 grounded but unhook the ground jumper from terminal #1. That should cause the motor to run (at low speed) until it reaches its park position at which point it should stop. If the motor operates normally in the above tests but not when installed on the vehicle then the problem is most likely in the switch or maybe the wiring. Also, the switch has to be grounded to the dash or the wiper will not work. Don't forget to check the fuse. The switch can be tested with an ohmmeter. If the motor stops immediately when switched off (doesn't return to park position), first check the motor's ground strap. Since the motor is mounted on rubber cushions, it's grounded via a copper strap attached under one of the mounting screws. This is the ground for the park switch so the parking feature won't operate if the ground strap is missing, dirty, or corroded. If the ground strap checks out okay but the motor still doesn't go into park then the problem is most likely a worn out or dirty park switch. The park switch is located inside the motor's gearbox so some disassembly is required to check/clean the switch. I recommend consulting a good repair manual for the motor disassembly procedure. LockDoc |
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outstanding! I have it in the electrical FAQ now.
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LockDoc |
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Awesome writeup Leon!
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Nice job Leon!
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Thanks Leon, now I know why my wipers don't park themselves at the bottom of the windshield.
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Thanks guys. Glad it's helping out with the wiper problems... lockDoc |
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Another master piece to add to the library. Great job and info. :metal:
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Glad to see this one going into the FAQs, I have been linking Rays website for quite a while.
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Nice.
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A very good and needed write up on testing the wiper motors (Thank you)
I have some additional information included on my build thread that might be of interest to you or others in troubleshooting their possible problems or wiring the system for a 67 – 72 Chevy truck (post #527) http://67-72chevytrucks.com/vboard/s...318544&page=22 I did barrowed the wiring drawing picture in your post to help clarify/understand my post better, hope you don’t mind and also created a link to your post in mine. Bruce |
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LockDoc |
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Thanks this helps alot ,I'm in the middel of replacing the wireing harness in my 67 was not sure if the wiper motor even worked. I'm going to test mine right now.
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Subscribing for future use. Nice work!!
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:metal:
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Wiper motors have always been black magic to me. Thanks very much!
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Finally got around to replacing the bad wiper motor, now we have working wipers that don't park on a new motor....
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Let me know what happens. LockDoc |
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Thanks Doc, will try tomorrow....
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Tried to ground it with clips, still no park. I may pull the motor back out, scrape off any paint that may be the culprit.... who knows.... motor from Oreilly's might just have a bad park switch anyway.....
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I think One of the mounting bolt holes should have a brass washer with a strap that grounds to the wiper motor. LockDoc |
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I have a question. On the two speed motor you show three terminals on the motor. Mine has 4 terminals. How do I test this motor?
EDIT: (See posts #66 & 67) |
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LockDoc |
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Thanks for this useful thread and the help with the wipers! |
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The truck is a 1970. I will try to post a picture but have not done it before. Hope it works.
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LockDoc |
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LockDoc |
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I just got done using these instructions to bench test a wiper motor and it was a breeze! I took some pictures of a little wire harness I made up for it:
Red wire to the hot terminal, black to motor housing, with a leg off with a spade connector. http://i3.photobucket.com/albums/y55...hwiring001.jpg With the red and black to a 12v source and the white jumper on both terminals, this is run slow: http://i3.photobucket.com/albums/y55...hwiring002.jpg Just like above, but with the jumper off, is run high: http://i3.photobucket.com/albums/y55...hwiring003.jpg Jumper connected again, but black (ground) off, return to park: http://i3.photobucket.com/albums/y55...hwiring004.jpg Thanks to LockDoc for this thread! |
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Thanks. Glad you found it useful. I keep a small motorcycle battery around to test them with. It doesn't take much. LockDoc |
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Where does the windshield washer pump play into this? in the pictures above, the 2 terminals, what should go there? I'm running an aftermarket wiring harness, so doing a lot of this from scratch.
Also, while the wiper motor terminals are clear, but what goes to what, from the switch? my switch has the 3 terminals, 1 high, 2 low, same with the wiper motor. _ 1 goes to ? _ 2 goes to ? _ 3 goes to ? and on the wiper motor, _ 1, 2, or 3? _ 1, 2 or 3? _ Power _? _ ? on the backside of the pump I'm also assuming that the washer function gets jumpered in here somewhere? |
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This thread might help with the wiring. http://67-72chevytrucks.com/vboard/s...d.php?t=584603 LockDoc |
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I recently bought a new two speed wiper for my 67 gmc and it worked fine when I tested it before install. Ever since I put it in it will not work. I do not have the washer motor on the wiper motor because I didn't think it mattered and I checked the voltage and there is 12 volts everywhere in the circuit all the way to the wires that plug into the switch. The only thing I haven't done is tested the switch with an ohm meter because I do not know how. Could you please explain exactly what you mean by that i do have a dmm so I can if i know how. And any other suggestions to try are welcome :D
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The washer would not make a difference as long as all of the original wiring was there... Is the switch installed in the dash and the nut tightened up? It has to be to work because that is where the circuit gets it's ground. As far as testing the switch, unplug the connector from the switch and set the meter to the lowest ohm setting, which should be 20k ohm. Turn the wiper switch to the low position and touch one of the leads to the switch body and the other lead to one or the other of the connectors. You should get a reading when you touch the low speed connector (I can't remember which is which). Then turn the switch to the high setting and touch the other connector you should get a reading. In the off position you should not get a reading. LockDoc |
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This has been an excellent read. I have gutted the dash on my '70 and cleaned it up, replacing some of the switches. Presently I have a two speed wiper setup with a push in wash.
I would like to replace the switch such that I have an intermittent feature but I do not know if I can just replace/install the switch or if I would have to upgrade the motor also. I have been looking at different switches and have run across a term I am not familiar with: coast to park and dynamic park. I have the rectangular motor like the one pritch has pictured. I believe it is dynamic park (?) |
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Glad you enjoyed the thread. One of our members on the board sells the delay kit on the parts for sale forum. Here is a link to his for sale thread. http://67-72chevytrucks.com/vboard/s...d.php?t=593984 I am not familiar with those terms either so I can't help you with that. LockDoc |
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Wiper motors are voodoo! Until I read this thread. Now they are just a pain in the brain!
I have a 69 C10 with a 3 terminal (2 speed?) wiper motor. 12V at the motor. Jumped the wires as instructed above and get just one speed . Removed cowl and freed the wiper transmission arms so motor could run free. Still just one speed. Suggestions? Thanks guys! |
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Thanks for the link, LockDoc. It looks like the thing I have been wanting but recently my time has been consumed with so many other things it may be a little while before I fit one iota (is that a word?) of more part replacement. Right now its a mad race with the warm weather and short days to get everything done that need done immediately.
Turns out that my wiper motor works just fine. However, while it was apart I couldn't resist screwing with the washer motor (had to figure out how that ratcheting pawl worked) and I think I may has put it back together in a position different than it should be. I bought a little rebuild kit and rebuilt it (the washer mechanism) and while in there I just had to know what made that ratchet mechanism stop and go. So, I discovered the if I push the piston down against its spring, the rachet mechanism will move to various positions. Neat! But now that my friend has re-installed the wiper motor, the washer doesnt seem to draw fluid. Does anyone know if there is a particular position that mechanism must be in to start properly? Maybe I should put a multimeter on the switch and check for juice. |
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I don't have the same type of prongs as the ones pictured above. I have three total to hook up to. I don't understand the part about hooking up to the "bottom terminal on the round motor."? I did get mine to run, it chugs along in one speed. How can I check from here to see if two speeds work?
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here's a closer picture of the prongs on my wiper motor. Just three of them.
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