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73-87 Chevy _ GMC Trucks => Electrical => Topic started by: Fairlane514 on September 24, 2014, 09:18:11 PM

Title: Wipers won't turn off 1985
Post by: Fairlane514 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.
Title: Re: Wipers won't turn off 1985
Post by: bd 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?
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 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.
Title: Re: Wipers won't turn off 1985
Post by: bd 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?
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 09:02:50 AM
Yes, it does exactly as you describe.
Title: Re: Wipers won't turn off 1985
Post by: bd 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.
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 09:28:51 AM
Ok, Thanks …..I will check the grounds
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 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….
Title: Re: Wipers won't turn off 1985
Post by: blazing816 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.
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 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.
Title: Re: Wipers won't turn off 1985
Post by: bd 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.
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 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.

 
Title: Re: Wipers won't turn off 1985
Post by: zieg85 on September 25, 2014, 10:52:56 AM
How is the ground between the cab and frame?
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 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.
Title: Re: Wipers won't turn off 1985
Post by: zieg85 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
Title: Re: Wipers won't turn off 1985
Post by: bd on September 25, 2014, 11:21:53 AM
I thought you went through the ground carrousel once before - lol. 

As Zieg pointed out:
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 01:38:38 PM
Tested all my grounds, as you have listed….all good. Im going to get another "new" wiper switch….Its the one component that causes the issue when plugged into the system
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 02:07:19 PM
Ok, here something else I tried.  Using continuity …….On my new switch plug end, I placed one probe on the solid black wire. Then I touched the other probe to each wire to see if i had continuity. The blue wire showed continuity in the "off" position. As I rotated the wiper switch to delay , Lo and Hi, continuity would change to different wires.  This seems normal, except I would expect no continuity between the black wire and any other wire in the "off" position.

On my old switch the black wire had continuity with the purple wire. I cannot verify if the old switch is in the "off" position because the detent is broken, so it just spins freely. Both switches cause the wipers to come on when the ignition key is in the on position.

 I was able to break continuity in the new switch between the black wire and blue wire, by turning the knob to "mist."  Unfortunately when I plug the system back together and turn the knob to "mist" the motor still runs in Lo.

Im taking my multi meter with me to the auto parts store and test the "new" new switch and see if its the same.
Title: Re: Wipers won't turn off 1985
Post by: bd on September 25, 2014, 02:11:38 PM
Black should connect to black/light blue in the off position to complete the park circuit.
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 03:47:13 PM
Ok, that appears to be correct in the new switch.  I went to the auto parts store and another new switch tested the same….blk and light blue have continuity in the off position.

Also, just want to verify…..there is not a relay anywhere in the system, right?
Title: Re: Wipers won't turn off 1985
Post by: bd on September 25, 2014, 04:24:23 PM
No relays from the factory.
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 05:05:01 PM
Well……I'm at a total loss.  I pulled the fuse block from the firewall, no wires seem to be melted or corroded.
Title: Re: Wipers won't turn off 1985
Post by: bd on September 25, 2014, 05:14:36 PM
No continuity between the individual wires when disconnected from the switch and motor?  And, no continuity to ground on any of the wires when disconnected?
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 06:33:53 PM
With wiper switch disconnected from motor harness,…….continuity between gray-blk/lt blue        purple-blk/lt. blue       purple-gray

  With the whole system hooked up and key on (motor running in the off position) I have power to the white wire on the motor (3 wire terminal) and faint pulses on the gray wire. With that 3 wire terminal disconnected I only have power to the white wire.

 With motor running in the off position from the inside I have pulse low power at the gary wire only on both sides of the motor harness and the wiper switch to the column.

 Wiper switch terminal from column unplugged, key off…..purple wire has continuity to ground
Title: Re: Wipers won't turn off 1985
Post by: Fairlane514 on September 25, 2014, 06:50:21 PM
FOUND IT!!!!!!!!      The purple wire had a small break in the insulation and was grounding out just under the turn signal switch. The purple wire ground continuity was the big clue.

Thanks bd!
Title: Re: Wipers won't turn off 1985
Post by: bd on September 25, 2014, 07:27:09 PM
That's GREAT!!  Cause we were running out of options...!  -LOL
Title: Re: Wipers won't turn off 1985
Post by: Nthefamily on October 31, 2019, 02:27:52 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?

bd,
I understand this is an old post, but ran across it when searching for answers since I have encountered the same issue with my wipers on my '85 K10 not turning off unless the ignition is off.

The wiper motor is only several years old and I've driven the truck maybe 800  miles since I installed new wiper motor which was only once in the rain (no I do not drive it much at all).

Things I've tried:
1) Eliminated the delay module out of the circuit and wipers still stay on with the wiper switch in the off position (have column mounted switch & tilt column). Wipers do not change speed nor do they delay when operating the switch, only run on slow speed.

2) Unplugged the park terminal from wiper motor and wipers stop anywhere on the windshield when unplugged

3) Removed park terminal apparatus from w/w motor, plugged the 2 wire harness up to it, turned switch on and pushed the bracket on back of park terminal to break the connection (similar to ignition points) and w/w's stopped. They didn't park at bottom of windshield, but did stop running.

4) As you state above in your quote - I unplugged my switch and grounded the gray w/ignition on and w/w motor ran at slow speed, grounded the purple and it seemed to have sped up some while running; grounded the blk/lt blue and it kept running on slow.

Question in regards to the quote above where you gave suggestions to try with the wiper switch unplugged: With w/w motor continuing to run when grounding the blk/lt blue, does this sound like my switch or the park switch on motor?

Thanks
 
Title: Re: Wipers won't turn off 1985
Post by: bd on November 01, 2019, 02:02:41 PM
Most likely a mechanical problem with the park switch mechanism or a faulty park switch.  There may be a less-than-perfect ground to the dash switch, too, as a separate issue.  Remove the washer pump assembly and reconnect the wiring to the w/w motor.  Watch the rotation of the nylon cam and the interaction between the cam lobe and the park switch.  Make sure there is no broken or missing spring.
Title: Re: Wipers won't turn off 1985
Post by: Nthefamily on November 01, 2019, 02:48:02 PM
Will do, thanks.