Windshield wiper motor not working

Tiny
CMINION718
  • MEMBER
  • 1998 ISUZU HOMBRE
  • 5.7L
  • V8
  • 2WD
  • AUTOMATIC
  • 3,000 MILES
I have tried to find this for days and cannot seem to find the diagram. I have been looking for what connector on the pigtail for the windshield wiper motors need to be on for high (get power to). I have a ground in the middle one and the bottom right one gets twelve volts on high but I need to make sure that is right one. This truck is custom built and I traded mine for it. The windshield wipers do not work and have tried three motors now and none of them work even though power goes to connection when I test the pigtail. I can no no matter what I search fine what needs to be powered on the pigtail for high to work. Also, I cannot find it anywhere if the motor is grounded through the bolts that hold it to firewall.
Friday, May 4th, 2018 AT 4:56 PM

12 Replies

Tiny
HARRY P
  • MECHANIC
  • 2,292 POSTS
Here is a wiring diagram. I hope this is what you are looking for. Look at the purple wire. I would splice into it temporarily and run a hot wire to it. If the wipers start going, then the problem is likely in your multi-function switch.

As far as the grounding, I am not entirely sure of how it is grounded. I would take a multi-meter and check for continuity (by setting the meter to ohms/resistance) between the bolts on the firewall and the negative terminal. If there is continuity there, then that is likely your ground.

Finally, you might also check the purple wire at the wiper motor connector and see if it gets power when the switch is powered on.
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Friday, May 4th, 2018 AT 8:11 PM
Tiny
CMINION718
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You did not link a wiring diagram. I was looking for what wire on the pigtail that connects to windshield wiper controls what. Middle is ground I know but is bottom right on connector for high? Instead of splice I guess I could find a twelve volt source and run wires into the connectors where it powers it but then comes the problem of I have no idea which one and do not want to burn up the motor. The only one I know is the ground.

When I check the pigtail for power if I move the switch from low to high the power (twelve volts ) goes away in the bottom right connector. I know there is a fuse power one to and not sure if that needs power along with the high power for it to work I looked at every fuse I could find that he put in the custom wired vehicle (it is a bagged show truck, body dropped with a LT1 engine put in it, shaved firewall, and a 1996 corvette computer put in it ).

I will try to check for ground on the bolts that way so thank you for that but yes this thing has been giving me such a headache. I would just like to be safe if it rained some time I drove it, lol.
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Saturday, May 5th, 2018 AT 1:27 PM
Tiny
HARRY P
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Sorry it must not have attached properly. I will redo it when I get home.
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Saturday, May 5th, 2018 AT 3:28 PM
Tiny
HARRY P
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Here. If I am reading it correctly, you should be looking for a purple wire going to the wiper motor. That is supposed to be the high speed power wire coming from the switch. If there is no power coming from there when the switch is on "high, " suspect a bad switch. Those multi-function switches are problematic, so I would not be surprised one bit. Confirm by running twelve volts to it for just a moment. If the wipers move, then your switch is bad.
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Saturday, May 5th, 2018 AT 6:58 PM
Tiny
CMINION718
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I have no idea how to read that. I know some electronics but what I was looking for was was the power out of the pigtail/connector to the windshield wiper. This is the connector and B I have ground, D I have twelve volts but I was needing to know if that is for high. Do you have to have power at E too? I think that is fuse power but I do not know? When I turn the wiper switch inside to hi the power comes on for D to twelve volts and goes off if I turn it to anything else, so I would think the switch is fine. Thank you for helping this has been driving me crazy. I thought about taking to electric specialist since it is all custom wiring. Here is picture of engine to so you can see how little is in there.

Edit : After looking at it more I understand how to read it somewhat now, and I see the color wires. I think mine has some I will check tomorrow to see so that diagram might come in handy then. But you can see why I am having issues I think, lol.
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Saturday, May 5th, 2018 AT 8:24 PM
Tiny
HARRY P
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Does this look right?
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Sunday, May 6th, 2018 AT 3:44 AM
Tiny
CMINION718
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That is it, thank you heyman. Now the question is, I do not get any power on C so does that mean it would not work because no power on that line? Would that be a fuse or relay? I could not find any blown fuses but it could be somewhere else in wiring since a lot of it is custom.
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Sunday, May 6th, 2018 AT 6:14 AM
Tiny
STEVE W.
  • MECHANIC
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No power on C = no power to the wiper motor. The logic board on the motor uses the power from C to activate the motor based on the inputs from the other pins.

You need a good ground on PIN B
Battery voltage through a 25 amp fuse to PIN C

Now the other pins are the controls.
Turn the wiper switch to HIGH and you should get battery voltage on PIN D
Now for low speed constant wipe it should show battery voltage on PIN E.

If you switch to the intermittent/pulse wiper function the voltage on PIN E will go lower as the intermittent wipe interval gets longer.

For the washers function it applies battery voltage at PIN A and also turns on the washer pump in the bottle. When you press only the washer function with the wipers OFF the wipers will sweep and return to park as long as you are holding the washers on. When the wipers are ON the washer function only triggers the washer pump and the signal on PIN A is ignored.

To test the wiper motor and verify it works is easy. Disconnect the plug. Run a jumper wire from battery negative to PIN B on the motor, Run a 25 amp fused jumper wire to PIN C on the motor.
Now take a short jumper and apply battery voltage to the various motor side pins to test the functions
Voltage to PIN D and the motor should come on at high speed.
Voltage to PIN E and you should get low speed wiper.
Voltage to PIN A and you should get 1-3 sweeps and back to park. (Depends on the actual motor logic)

Hope that helps.
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Sunday, May 6th, 2018 AT 8:04 AM
Tiny
CMINION718
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Steve, I will try that thank you and yes I figured if it got power on D but not on C also then it would not work. The vehicle was wired to only have high work so I cannot test any of the other settings, lol. Will try this though but the hardest part is my batteries ( I have two) are in the most rear part of the bed under the bed liner that has been raised due to the C notch.
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Sunday, May 6th, 2018 AT 3:01 PM
Tiny
STEVE W.
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Starter solenoid is a handy place to "borrow" battery voltage from in that case. Would not be hard to use a universal wiper switch to give you high/low/park and wash if you wanted. You would use the power feed you have already to power the motor and go to the new switch. You would add three wires to the other connections. Go find an S10 or Blazer in a salvage yard and grab the wiper harness. Clean it up and use it to wire in the motor. Have built many custom vehicles and they all had fully operational wipers. Nothing like going to a show and then driving back in rain without any wipers, Rain-X is good but not that good.
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Sunday, May 6th, 2018 AT 6:54 PM
Tiny
CMINION718
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Will a bad relay cause no power on the fuse power? I went through all the fuses and they are good. When I check there is no fuse power so that is why it is not working. If the switch is turning the power on and off on the connector for high (it is only wired for high) could it be the windshield wiper switch? Does power run through that for the connector for the motor?
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Tuesday, May 8th, 2018 AT 9:58 PM
Tiny
STEVE W.
  • MECHANIC
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Everything runs through that connector both power, ground and control feeds to the wiper motor. A bad relay can cause a lack of power.

Pin A - Dark green wire - This is the wash/park connection on the OEM harness. This is fed battery voltage directly when the washer button is pushed. However it is also fed battery voltage through a 24 Kilo-ohm resistor whenever the wiper motor switch is in any position other than off.

Pin B - This is a heavier black wire that goes directly to a good ground.

Pin C - This is a yellow wire, It is the main motor power feed, and goes to battery power through a 25 amp fuse. It also splits off to feed through the wiper switch.

Pin D - This carries battery voltage when the switch is on high speed only.

Pin E - This carries full battery voltage for low and high speeds. And a reduced voltage on this pin also allows for the intermittent wiper speeds.

Attached you will find the connector and two schematics. The first is the original. The second is stripped of the washer and intermittent controls. It will give high and low speeds only.

Which switch do you actually have for the wipers? The factory switch or something else? If it is the OEM switch you may as well use it and get all the functions. The wires are all needed to control the motor anyway. (Other than the red wire for the washers if you did not want to bother with those)

Did the wipers work before this or are you wiring them up?
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Wednesday, May 9th, 2018 AT 3:27 AM

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