Windshield wiper system/ TAC Unit?/ Wipers do not park

[stesir]

Cannot get the windshield wipers to park. They go slow and fast but do not shut off, unless you turn of the car.

What is the TAC Unit and where is it for the wiper system? What is the beeping for the interval wipers system and where is that located?(The beeping) The wiper motor and relay are good.

Thanks.

[vbrad511]

Under the drivers seat.

[mikec]

The TAC unit has nothing to do with the park function of the wipers. TAC only operates the intermittent wiper mode... by triggering the wiper motor for just a second or so to get it started on the motor's LOW speed.

 

The wiper on/off switch and the TAC both supply a path to ground to start the motor. The motor runs as long as the wiper on/off switch is not in the OFF position or the TAC unit repeatedly grounds the motor for a second to "do a swipe" pass. Once the wipers are moving, small switch contacts inside the wiper motor gearbox assembly keep the ground "alive" to the motor until the wipers reach the park position, then the switch contacts open. Those switch contacts get dirty, or contaminated by old and dried-out grease inside the gearbox, or just plain wear through. Without them, the wipers won't park. And the intermittent mode doesn't work right either when this gearbox switch is bad... the wipers swipe a bit, pause, swipe some more, pause again, etc. as the TAC sends out its roughly 1 second pulses. These gearbox switch contacts are a very common failure on StarQuests and many other cars. And not too difficult to fix - just take stuff apart and you'll see how it ought to work.

 

By the way, the gearbox body is supposed to be grounded to the car body... look for a blue wire on one of the screws. if that ground contact is bad then the gearbox switch can't do its job.

 

mike c.

[stesir]

It def was the TAC....the contacts inside the wiper motor were like brand new...the TAC has some rust on it and is shorted out. It's a 1987 car MB571381.

Can any other years work?

Thanks