wiper electrical issue

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Jul 15, 2010 | 09:44 PM

thegringo

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wiper electrical issue

New to the forum, and just purchased a 78 F100. I'm having an issue with the wiper system. The previous owner said it was the wiper motor, as he had recently replaced the switch, and included a new (reman'd) one with the truck. It has intermittent wipers (switch), and the issue is that when I turn on the wipers the motor only engages in the high position and then cuts off when the wipers are fully up. If I then turn them off, the arms go back down. The intermittent position does not work, and the low setting does not work. After a day of digging around under the dash; I finally got the old one out and the new one installed and wired up the same way the old one was and I am still having the same problem. This leads me to believe that this is a wiring issue, but electrical systems are not my forte. Can anyone help me troubleshoot this? Thanks.

Jul 15, 2010 | 11:10 PM

thegringo

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I figured out the problem... It looks like the previous owner replaced the wiper switch with an intermittent switch, however the truck isn't fitted with the full intermittent system. Quick fix will be to replace the switch with the proper one, and the long term solution will be to find the complete system.

Jul 16, 2010 | 08:19 AM

fmc400

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From: Austin, TX

Let us know what happens when you replace the switch with a regular one. I was first under the impression that the control module was part of the intermittent switch, but I'm looking at a schematic and it's showing a governor as separate from the switch. So at this point I'd agree with your logic.

Jul 16, 2010 | 09:07 AM

mikeo0o0o0

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From: Stanley, VA

On the intermittent wipers there is a seperate "box" (governor). The wiring harness from the wiper motor plugs into it instead of the switch, then the switch plugs into the short harness from the governor.
The way to tell the difference between the switches is the standard switch only has three positions, off, low, and high, and you turn the switch clockwise. The intermittent switch has those three positions plus from the off position you can turn it counter-clockwise to adjust the delay.
If I remember correctly, either switch will plug into the harness but only one will work. Also for the delay wipers to work correctly, the switch must be grounded or the delay part won't work.

Jul 16, 2010 | 01:05 PM

81-F-150-Explorer

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From: Northern California

I was going to suggest that, either a govenor or ground problem will cause the same symptoms as a wrong application switch.

Jul 16, 2010 | 06:44 PM

thegringo

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Thanks for the troubleshooting help. It was the switch after all. I will have to call and thank the guy who sold me the truck and told me it was the motor since he had "replaced the switch". Now that that's done, I'm going to hit the yards for a proper intermittent setup.

Jul 16, 2010 | 07:50 PM

81-F-150-Explorer

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From: Northern California

1973-1979 F-series
1978-1979 Bronco are direct swaps.

Also compatible are...

1980-1991 F-series
1980-1991 Bronco
1980-1999 F-600/F-900

But you have to move the windshield washer pump wire for the washer pump to work.