Author Topic: Wipers won't turn off 1985  (Read 28578 times)

Offline Fairlane514

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Wipers won't turn off 1985
« on: September 24, 2014, 09:18:11 PM »
85 Blazer….new wiper motor, new wiper switch.  As soon as I turn the key to the on position the wipers come on. It will go from Lo to Hi, but refuses to turn off.

I do have intermittent wipers and I have bypassed the delay or pulse module with the same result. I have removed the two wire plug from the park switch and it keeps running.

The wiper motor was not installed when I bought the Blazer but it was brand new in a box. The rubber isolators were also missing, but I tracked some down and mounted it. There is no ground strap or loop or anything else grounding the motor to the body. I don't know if this is correct and I need to ground it somehow. I checked for continuity on the two ground wires from the lower harness that powers the motor and they tested good.

I have also plugged in the old wiper switch and it does the same thing. Before replacing the wiper switch, the wiper motor would function normally , but without a delay or pulse, just Lo and Hi. Now that I have replaced the wiper switch they come on with the key and won't turn off. It is the correct switch for a tilt column and delay wipers.

I did do a search and some had very close problems to mine, but not exact.

Online bd

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Re: Wipers won't turn off 1985
« Reply #1 on: September 24, 2014, 09:28:49 PM »
The wiper switch provides ground to the w/w motor to control motor speed.

1. 'White is B+ (12 volts with ignition ON)

2. Gray is Lo (when grounded by the dash switch)

3. Purple is High (when grounded by the dash switch)

4. Black/Light Blue is Park and grounds gray (Lo) through the park switch when the dash switch is in the OFF position

Sounds as though you might have a gray control wire grounding somewhere between the switch and the motor, or inside the motor assembly.  Does it continue to run if you unplug the dash switch?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Fairlane514

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Re: Wipers won't turn off 1985
« Reply #2 on: September 24, 2014, 09:38:53 PM »
When I unplug the dash switch it stops.

I did use a test light on the lower power supply plug with the three wires (white, gray and purple) while it was running. The white was power with a bright test light, the gray was a very dim test light in Lo, and I didn't test it in Hi.
« Last Edit: September 24, 2014, 09:43:13 PM by Fairlane514 »

Online bd

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Re: Wipers won't turn off 1985
« Reply #3 on: September 24, 2014, 11:38:29 PM »
If you unplug the wiper switch and ground gray with ignition on, the w/w motor should run at low speed; ground the purple and it should run at high speed; ground the blk/lt blu and it should park.  Does it?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Fairlane514

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Re: Wipers won't turn off 1985
« Reply #4 on: September 25, 2014, 09:02:50 AM »
Yes, it does exactly as you describe.

Online bd

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Re: Wipers won't turn off 1985
« Reply #5 on: September 25, 2014, 09:23:55 AM »
Assuming the delay module is still removed from the circuit, it sounds like a switch problem. 

Because of something you posted earlier, physically remove, clean and verify proper grounding of the black wire coming from the w/w switch harness.  It should ground near the e-brake pedal.

And, install a ground jumper between the w/w motor case and cab ground - this should have no electrical effect except to help shield EMI from interfering with radio reception.
« Last Edit: September 25, 2014, 09:56:40 AM by bd »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Fairlane514

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Re: Wipers won't turn off 1985
« Reply #6 on: September 25, 2014, 09:28:51 AM »
Ok, Thanks …..I will check the grounds

Offline Fairlane514

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Re: Wipers won't turn off 1985
« Reply #7 on: September 25, 2014, 09:48:31 AM »
The solid black wire from the harness goes into the large bundle of wires and then routes behind the fuse block. I don't see a ground near the E-brake pedal. I also placed a ground wire into the black wire "pin" location and no change. From the motor side, a ground wire made no difference.

My old w/w switch acts the same when I plug it in. Maybe I have two bad switches….

Offline blazing816

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Re: Wipers won't turn off 1985
« Reply #8 on: September 25, 2014, 09:49:22 AM »
Post what you find on here please, because I am curious. I have wippers that will shut off but when they want to, sometimes I have to go from high and swtich it fast to off to stop them, or go the washer juice to get them to stop....really annoying.
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1988 Chevy R20 Scottsdale Crew Cab (350/TH400/4.56)

Offline Fairlane514

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Re: Wipers won't turn off 1985
« Reply #9 on: September 25, 2014, 10:12:49 AM »
http://forum.73-87chevytrucks.com/smforum/index.php?topic=10154.msg71196#msg71196

 I did the test on this diagram. Mine would not start when I added the 12v at the '19' position.

Then i did a continuity check of the 17 and 18 wires and they were good to the plug that connects to the w/w switch harness from the steering column.
« Last Edit: September 25, 2014, 10:14:54 AM by Fairlane514 »

Online bd

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Re: Wipers won't turn off 1985
« Reply #10 on: September 25, 2014, 10:28:30 AM »
If all you connected to the motor was 12 v to #19, it shouldn't run.  That just indicates the motor isn't grounding internally.

I hesitate at two switches being bad, but it's not unprecedented.  Replace the delay module and re-verify you have the correct switch.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Fairlane514

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Re: Wipers won't turn off 1985
« Reply #11 on: September 25, 2014, 10:35:24 AM »
Verified new switch with old both by visual comparison and plugging back in the delay module. The wires are in the exact same position and color as the old switch.

 

Offline zieg85

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Re: Wipers won't turn off 1985
« Reply #12 on: September 25, 2014, 10:52:56 AM »
How is the ground between the cab and frame?
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline Fairlane514

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Re: Wipers won't turn off 1985
« Reply #13 on: September 25, 2014, 10:56:13 AM »
I have the 10 gauge wire from the battery ground cable bolted to the core support.  Grounds for stereo etc seem good from inside the cab.

Offline zieg85

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Re: Wipers won't turn off 1985
« Reply #14 on: September 25, 2014, 11:08:50 AM »
Body to battery is important but to frame is equally important.  I've had weird things not work and it always was a bad ground usually due to an engine change, cab fire wall to back of head braided wire ground either missing or not tightened up
Carl 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
https://www.facebook.com/groups/248658382003506/