[BlueSS454]

I'm looking for some ideas on what could be causing a little problem I'm having working on a 72 so I know where to start looking.
Currently, the wipers will stay ON when the switch is in the "OFF" positions. The speeds slow and fast work properly. When the switch is moved to the OFF position, the wipers will go to park then kick back on and stay running. There is a new wiper motor and new switch installed. I know it's not the motor as it has done this on 2 different ones.
I am thinking this is a ground issue but I need some guidance on where to start looking. I HOPE this is not a misindexed wire somewhere, that would suck. I know 72's are in a world of their own with wiring so any help is appreciated. It is a U14 gauge setup.

 

[Philip]

It is a ground issue. The switch completes the ground path so check the switch and the wiring from it to the motor. If the wiring is good it could be the wiper motor. There is also a parking circuit inside the wiper motor so the wipers do not shut off with the key on until they are in the parked position.

 

[Philip]

Here is a photo of the park latch assembly for a round wiper motor. The white box pulls in the latch to allow the motor to run. When the switch is turned off (ground path removed) the latch swings out and stops the motor when it cycles around to the park position. It can be replaced separately.

The square motor has a similiar circuit, but I do not have a photo of it.

 

[Coppertop]

Tom,

Don't know where you are on this project...a thought...

I can't remember if you can safely operate the wipers with the hood up (don't know if they will rub on the rear of the hood and cause damage), but if they will operate okay, a trick you can try is:

Turn the wipers on low speed. While they are running, unplug the single light blue wire. If the motor turns off and parks correctly, the problem is NOT with the motor and the motor's ground under the hood.

 

[BlueSS454]

Phillip & Joe,

Thanks for the tips. I'll see what I can come up with tomorrow. I didn't have time to mess with it tonight. The hood is off the car so no worries there . I do have a pinout of the bulkhead printed so I can check the indexing of the wires.

 

[rick]

Tom, Picture of 72 motor & switch wiring: http://www.chevelles.com/showroom/data/500/70wprmtr.jpg For reference.

 

[BlueSS454]

That's a 70 switch. The 72s have a 4 terminal connector containing 2 grounds.

 

[Coppertop]

Actually, there is only 1 ground connection.

In '72, GM went with an integrated ground connector. The "offset" connector is chassis ground. It's black.

Then you have the 3 control lines which are in a straight row.

These are the functions:

Light blue--sends out a ground when ever the motor is running regardless of speed.

Dark blue--sends out a ground when you push in the button for "wash" to activate the pump solenoid.

Black--sends out a ground when switch is in LO speed and OFF only, directly grounds the shunt windings in the motor to reduce the speed. It is grounded in off to make sure the motor is not running in high speed during its off/park cycle so it doesn't skip a beat.

:beers: