2000 Mercedes Benz 320e Wiper starts with switch off

  • 2000 MERCEDES BENZ 320E
Electrical problem
2000 Mercedes Benz 320e All Wheel Drive Automatic 88,700 miles

The windshield wiper has started cycling at random with the wiper switch in the off position.

The wiper has also started cycling once each time the car is started.

Depending on humidity the problem increases.

Any history with this issue?
Do you
have the same problem?
Sunday, April 4th, 2010 AT 11:05 AM

1 Reply

Hi BUGAS. I'm not an expert on your brand of car, but I can offer one possibility. Chrysler had a problem called "phantom wipe" that was very similar to your description. It was caused by hanging a very unreliable, trouble-prone computer onto an otherwise simple wiper circuit. The Body Computer interprets the wiper switch setting based on which of the various resistors are switched into the circuit by the multi-function switch. (That's a fancy name for the turn signal switch). Some of the resistors are out of tolerance just enough to confuse the computer. Depending on temperature and humidity, two things that affect the value of the resistors, the computer thinks you've selected the lowest delay setting and takes one swipe of the wipers. This affected the minivans only. The wipers could remain off for weeks or they might take a swipe once every hour.

The cure was to replace the signal switch. The interesting thing about it is it has three part numbers on it. One is for Chrysler, one is for Toyota, and the third one is for, ... Well, we don't know who the third one is for. This problem usually took a few years to show up.

Another problem I ran into once, again had to do with that silly Body Computer, but this time it was on a car. There was a spot of corrosion in the electrical connector between three adjacent pins. One was the wire coming from the wiper switch and one was for the tail lights. The wipers would run on the lowest delay setting whenever the headlights were turned on. Took quite a while to find that one, but it was a simple, one-minute fix to clean the connector.

I don't know if these ideas will lead to a solution so I would welcome other people to add their replies.

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Sunday, April 4th, 2010 AT 3:19 PM

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