Wipers won't turn off! Defective intermittant module?

[Turbofiat124]

Since I have deviated from stock, I may be on my own on this one but since the Google is full of "wiper's won't turn off" on various other makes it may not have anything to do with my mods. Perhaps someone has had this happen with their stock wipers.

Back in the winter I plumbed in a 12 to 15 volt converter between the wire coming off the fuse box and the column switch. That way everything receives a consistently higher voltage (motor speeds, park mechanism, delay module, washer motor):

http://www.fiatspider.com/f15/viewtopic.php?f=6&t=32346

The idea was not to "overclock" the motor but to compensate for voltage drops between the battery and the wiper motor.

I'm also using a Bosch wiper motor from a VW Rabbit (Golf mk1) about 10+ years ago which is one step above the Marelli motor.



I initially had some issues blowing fuses when the wipers were on with the engine was not running. This seemed to be an issue related to the step up converter pulling more current because less voltage was being fed to it. I fixed that using a circuit breaker.

So yesterday I got the car out for the first time this season.

I initially only tested my wipers in my garage but wanted to see how they functioned while the car was running without it actually raining. So I removed my wipers arms and placed a piece of tape onto one of the spindles. The wipers continued to run with no problems until I got to work (about a 10 minute drive).

When I got to work I turned my wipers off but they continued to run! On intermittent mode, the wipers don't park, run then park but rather speed up and slow down to a certain degree. Sort of hard to describe.

However if I turn the speed knob from "fast" to "slow" the wipers will park and turn off. Then if I turn them back on to "fast" speed the problem comes back.

So this morning on the way home, I tried this again. This time the wipers turned themselves off when I got home so I thought it was some sort of fluke.

Today I tried the same experiment. About a mile from work I turned the wipers off but once again the same deal. Then when I switched the speed knob to "slow" then they parked and stopped.

Now if the wipers have been off for maybe a minute, I can turn them back on to high speed and they act normally.

I have not tried to run the wipers on slow speed continuously for more than 10 minutes to see if the same thing happens.

So here is my conclusion:

Problem seems to occur after wipers have been operating on high speed for at least 10 minutes
Problem maybe temperature related. ~35F: problem does not occur, >60F problem occurs (but maybe just a coincidence)
Turning speed switch from fast to slow will stop wipers and allow them to park
I don't know if this problem is just related to the fast speed or both speeds.

Some thoughts:

Perhaps the extra 1 or 2 volts I am feeding to the system could be causing the motor to run hotter causing some sort of cross flow to the park mechanism? Because I have increased the voltage, the current has dropped (OHMs law) so this should actually be easier on the switches.

However the one thing I am suspecting the most is my Russian made replacement intermittent module.

While working on the project I replaced the original intermittent wiper module which had been malfunctioning. The one I received apparently was for a Lada because it had Cyrillic writing on it.

I'm just wondering even though the wipers were not operating on intermittent mode, if this module was defective (or I'm feeding it too much voltage causing it to overheat), would it cause the wipers to act weird on constant speed?

If you unplugged the intermittent module, would the wipers still function without it? Or is it required for the wipers to operate at all? As you know if you remove the hazard switch, the signal lights will not function because it's all tied together. Unless of course you run a jumper wire across the connector.

In my case I have air conditioning so I'm going to have to remove my glove box to get to the module.

I just can't understand how turning the speed knob from fast to slow would "fix" the problem.

I know the intermittent module uses the park function in the motor to operate. So if perhaps the module is defective or getting to hot, it could be sending power to all three "fingers" inside the wiper motor causing it to run continuously.

[spider2081]

I believe the wiper delay functions the same on both wiper speeds. The speed switch selects different windings in the motor changing how fast the motor turns. The delay is a fixed period of time between pulses. The pulse drives the wipers out of the park position. So the speed switch changes hoe fast the wipers complete one sweep from park back to park. The delay between sweeps is the same regardles of which position the speed switch is in. If I read you post correctly I don't think the delay timer would work properly on one speed and not the other.

[Turbofiat124]

I have not checked to see if this problem happens when the motor is run on slow speed for 10+ minutes. It may just be related to the fast speed for more than 10+ minutes.

I did some research to understand why there are three brushes inside the motor.

There is a common brush, then there is one 180 degrees from it. When power goes through those two brushes, the motor spins "slow".

Reverse the polarity on the brushes and the wiper motor spins backwards.

Then there is a brush adjacent to the common brush. When power goes through these two brushes, the motor spins faster because there is less resistance across the commutater.

When the wipers start acting funky just like with the aftermarket unit on my Jeep and Yugo, I'm thinking power is somehow getting diverted to the slow and fast speed brushes at the same time. Now why this is happening I don't know.

My guess would be the only way power could get sent to the wrong brush was through the intermittent module. Somehow.