windshield wiper stopping issue

[DaveG39]

Lately when shutting off the wipers instead of the wipers homing to the usual place at the center edge of each windshield they stop wherever they happen to have been when they were shut off. Any suggestions to get them to work like they used to?

[Gdetrailer]

wnjj wrote:

MEXICOWANDERER wrote:
Wiper motors have battery power supplied directly to the motor as well as ignition power.

When the wiper switch is turned off, the battery power continues to supply the motor with power until the wipers arrive at their resting place. Inside the gearbox is a limit switch oriented to shut the wipers down when they reach the PARK position.

A broken limit switch inside the wiper gearbox would cause this. So would a fried wiper pigtail battery power terminal. There is no way to defeat the auto park feature except to turn the key off while the wipers are in action. So, the clue is to check battery voltage at the connector to the wipers. It's time to grab a 12-volt test light and access a factory wiring diagram. Blind parts replacement try-it-and-see is a poor diagnostic substitute.

Hey Mex, I think you contradicted yourself a bit. The wiper motor has switched power (from the wiper switch) and ignition power but nothing directly from the battery. That's how you can defeat parking, like you said, by turning the key off before they park.

Regardless, the park switch is almost certainly the problem and usually means buying a new wiper motor unless you're handy enough to take it apart and clean the contacts.

That is old school wiper motors (late 1980s on down), NEWER wiper motors do have unswitched battery power applied at all times AND they have an electronic circuit board which controls speed and park of the motor..

Had a friend with a 1990s vehicle that the wipers would continue running sometimes when the ignition was turned off.. Had to pull fuse supplying power to the wiper motor, wait 10 seconds then put fuse back in.. And all was well until it did it again..

[MEXICOWANDERER]

Back in the days of The Great White Fleet, I had a '51 Willys. Changed to individual wiper motors. Ganged switch. Momentary pushbuttons to park the wipers.

[DaveG39]

Thanks all for your help. Now to snake myself over the generator to see how well I can access the wiper motor.

[beemerphile1]

Was a common failure with Grand Marquis and Crown Vics back in the 90s and required replacement of the wiper motor assembly.

I installed a separate toggle switch so I could stop the wiper in the home position. The toggle worked the same as turning the key off.

[MEXICOWANDERER]

One look with a test light at the motor connect harness will yes/no establish whether or not battery voltage is continuous. There are several ways to operate the system and blade park and my initial response was to use a wiring diagram. I ran into mostly broken nylon parts and the remainder consisted primarily of broken limit switches. MoPars were famous for bad motor grounding. Very few people lube wiper blade linkage. And a few handymen use NLGI 2 grease in the transmission when number 0 is appropriate.

[wnjj]

MEXICOWANDERER wrote:
It's a limit switch over-ride. To test the "theory" yourself, grab a test light go to the wiper motor and stab wires or stick the probe into the connector block. Yes, chopping off the ignition switch does stop the motor.

Shut off the switch when wipers are in motion. They stop. Shut off the wiper switch then turn the key back on. The wipers park with the wiper switch turned off.

Many switch/park motors operate with a battery hot going into the motor. Then a "relay trigger" comes from the wiper switch to a genuine relay. This powers the wiper motor. Shut off the switch and the relay plays dead. Something needs to over-ride the relay that now has no power to the coil nor going through the power points. The battery voltage only powers the wiper motor until the cam opens the limit switch contacts. The relay over-rides the limit switch - when key is on and relay is operating. Yes this means 2 fused circuits. One for power, the other for the switch.

The test light will reveal all 🙂

We agree on how the park system works, other than I still say the "battery" power to provide the power to park comes from the ignition, not always-hot battery power. So one wiper-switched iginiton-based power source for normal operation and one ignition power source to provide park. Both can certainly share one fuse. Relays may be involved but only to reduce loads on switches.

I've had more than one wiper motor apart and fixed park issues before.

Now on some (most?, all?) later model vehicles, the computer controls the motor, using input from the switch and a low power park sensor signal (which is still in the motor). My buddy's Ram wipers sometimes just keep running a couple more cycles when turned off because the park pulse is missed by the computer.

Our Yukon runs the wipers when you wash and even does a spare wipe several seconds later but only if you're traveling at lower speeds so undoubtedly it's all computer controlled.

[dougrainer]

On RV Motorhome Wiper motors, the PARK is part of the Motor/Transmission. So, replace the Motor/Transmission if it fails to park correctly. Also, most of the time, if you attempt to turn the Key OFF to get it to park normally, it will move again once the Key is turned back on. Doug

[MEXICOWANDERER]

It's a limit switch over-ride. To test the "theory" yourself, grab a test light go to the wiper motor and stab wires or stick the probe into the connector block. Yes, chopping off the ignition switch does stop the motor.

Shut off the switch when wipers are in motion. They stop. Shut off the wiper switch then turn the key back on. The wipers park with the wiper switch turned off.

Many switch/park motors operate with a battery hot going into the motor. Then a "relay trigger" comes from the wiper switch to a genuine relay. This powers the wiper motor. Shut off the switch and the relay plays dead. Something needs to over-ride the relay that now has no power to the coil nor going through the power points. The battery voltage only powers the wiper motor until the cam opens the limit switch contacts. The relay over-rides the limit switch - when key is on and relay is operating. Yes this means 2 fused circuits. One for power, the other for the switch.

The test light will reveal all 🙂

[wnjj]

MEXICOWANDERER wrote:
Wiper motors have battery power supplied directly to the motor as well as ignition power.

When the wiper switch is turned off, the battery power continues to supply the motor with power until the wipers arrive at their resting place. Inside the gearbox is a limit switch oriented to shut the wipers down when they reach the PARK position.

A broken limit switch inside the wiper gearbox would cause this. So would a fried wiper pigtail battery power terminal. There is no way to defeat the auto park feature except to turn the key off while the wipers are in action. So, the clue is to check battery voltage at the connector to the wipers. It's time to grab a 12-volt test light and access a factory wiring diagram. Blind parts replacement try-it-and-see is a poor diagnostic substitute.

Hey Mex, I think you contradicted yourself a bit. The wiper motor has switched power (from the wiper switch) and ignition power but nothing directly from the battery. That's how you can defeat parking, like you said, by turning the key off before they park.

Regardless, the park switch is almost certainly the problem and usually means buying a new wiper motor unless you're handy enough to take it apart and clean the contacts.

[Roger10378]

Ditto on the park switch in the motor.

[MEXICOWANDERER]

Wiper motors have battery power supplied directly to the motor as well as ignition power.

When the wiper switch is turned off, the battery power continues to supply the motor with power until the wipers arrive at their resting place. Inside the gearbox is a limit switch oriented to shut the wipers down when they reach the PARK position.

A broken limit switch inside the wiper gearbox would cause this. So would a fried wiper pigtail battery power terminal. There is no way to defeat the auto park feature except to turn the key off while the wipers are in action. So, the clue is to check battery voltage at the connector to the wipers. It's time to grab a 12-volt test light and access a factory wiring diagram. Blind parts replacement try-it-and-see is a poor diagnostic substitute.

[agesilaus]

My first suspect would be the multifunction switch (the stalk on the side of the steering wheel) if your vehicle has one.

[fj12ryder]

What vehicle are you referring to?