See last post: Just a loose wire



Yesterday, while driving the wipers suddenly started jumping up and down from the "park" position, up about two inches, then back down to park. It wouldn't stop. If I turn the wipers on, they work fine, but turn them off, and they return to park, and start jumping again. Finally had to pull the light blue wire to the wiper motor.

Any suggestions? Ground problem maybe?

Problem is inside the motor.

That was pretty brief there John...

The wiper switch on a '68 is a grounding switch which means there is always power to the wiper motor even with the switch off. That the wipers work fine with the switch on and erratically with the switch off suggests a problem with the wiper parking switch located inside the wiper motor.

That was pretty brief there John....

Sometimes the boss sneaks up behind me.

Sometimes the boss sneaks up behind me.
Amen ;-)

I have been known to be a bit jumpy at times myself.

Before condemning the motor check the switch/wiring. Either the lt-blue or black will, or should, be grounded when the switch is off and in the low speed position, that wire goes in the two wire connector along with the yellow power wire. The other wire will, or should, ground when the switch is in the low and high speed position and is in the single wire connector.

I tore down this wiper motor and refurbished it about 6 months ago. The parking switch you are referring to.... I don't remember it. Is this an electrical contact or is it the mechanical park positioning lever inside the big plastic (blue) gear?

The stator, coils, brushes and gears, just about everything, are in excellent condition, and I only put new grease where the manual directed, or where it was obviously needed. The reason I was thinking it was a ground problem is because it happened once before, and I got it to stop by turning on the headlights! :confused:

I'm sympathetic about your boss John... Big Brother is watching me :cool:. But I'm changing jobs, so for the next month, I feel pretty liberated.

Before condemning the motor check the switch/wiring. Either the lt-blue or black will, or should, be grounded when the switch is off and in the low speed position, that wire goes in the two wire connector along with the yellow power wire. The other wire will, or should, ground when the switch is in the low and high speed position and is in the single wire connector.

Lemme see here... if I recall correctly there are exactly 3 wires going into the wiper switch on a '68: high speed, low speed, and washer. All are switched to ground at the switch to turn on their particular function. So none should be grounded in the off position.

The parking function of the wipers is both a mechanical and electrical device. There will be a switch to keep the wipers on while not in the park position. And there may be some interesting mechanical stuff going on for the retraction of the wiper blades.

I would have to either take one apart or study the manual to find more particular details.

The 68-72 hideaway wiper system.

1. Wiper switch. (grounds the three attached wires as follows)

Light Blue- grounded in Low-speed and Hi-speed positions.

Black- grounded in Low-speed and Off positions.

Dark Blue- grounded when pushed for washer pump operation.

2. Run solenoid. The Light Blue wire is grounded to lock out the park (mechanically prevents the wipers from being driven to the park position) and close the run/park switch.

3. Shunt winding. This winding is parallel to the armature winding.

4. Series winding. This winding is in series with the armature and shunt windings.

5. Run/Park switch. Closed when the run solenoid is energized (Light Blue wire grounded) or when the run solenoid is de-energized and wipers are not in park position.

6. Wash pump start coil. When the Dark Blue wire is grounded this coil latches the wash pump for one cycle.

7. Shunt winding resistor. Grounds the shunt winding during high-speed operation, bypassed (Black wire grounded) during low-speed and park.

8. Wiper motor fuse (25 amp) in fuse block. Has +12 VDC when ignition switch is in run or accessory position.

http://www.chevelles.com/showroom/wipermotor.jpg

Not shown in the illistration is the overload. If the wipers are unable to move, frozen to the windshield or???, the overload will open so that the motor doesn't burn it's self to the ground.

I suggest checking the wiring and switch operation because I had theblack and light blue reversed on my 70, I experienced the same malfunction "jumping up and down from the "park" position, up about two inches, then back down to park'.

I think the 68 black and blue are reversed from what is shown.

By the way the black wire is grounded when the switch is in the off position so that the wipers go to the park position in low speed. If parked in high speed the park switch can reclose and start the motor again and again and again...

I'm going to check the switch right now and post back. I'm obviously getting power to the motor while the switch is in the off position. Pulling the black wire stopped the behavior.
Thanks Elree, as usual, your replies are thorough and understandable. I triple checked all the wiring on the switch, and there is a mistake in the wiring diagram of the 68 service manual (Shows black and lt.blue wires reversed). Like I said, the wiper was operating perfectly for months.

I wish this were more helpful, but it appears to be just a loose wire at the wiper motor. It was either the black or blue, or maybe even the washer motor dark blue (or some combination of the above).

All I did was re-attach the blue wire (which I had pulled hastily in Meth-lab country), and noticed the other wire harness (with the yellow and black wire) was also loose... probably from me pulling the other wire, but who knows? Then I tugged on the washer motor wires and found the washer motor dark blue wire was loose inside the plastic connector, and not making good contact, if any, to the washer motor male terminal (By the way, if anyone has an extra one of these black plastic connectors, please sell it to me, mine is all beat up).

When reconnected, I turned on the ignition, and the wipers went up two inches, then parked. Now they work perfectly again. Thanks for all the help, and I apologize for not checking this more thoroughly before posting. I do remember I pushed in on the WIPER motor connections when the wipers were acting up, before I pulled them off. So maybe it's related to the WASHER connection????