Chrysler Repair: Wipers, fuse block, neon glow

Question
Hi Roland?I have a Chrysler Town & Country 2000 3.8 engine.When I turn on the wipers,on intermitent possition they work for around 20 seconds and then stop,but the fast and slow possition works good.Also,when the ignition is turned off you can turn the wiper switch on and it will work also.what do you think this could be?Thanks Jose

Answer
Hi Jose,
Do you have a voltmeter or neon glow lamp to test for 12V?
If the windshield wipers run with the ignition off then either the "wiper On relay" (located in the box under the hood near the battery) is stuck closed OR the body computer (located under the dash as part of the fuse block) is not doing its job and is stuck in the grounded state on the dark green/yellow wire that controls that relay. In theory when the ignition is off the power to that computer is turned off which should leave that wire floating so that the relay won't close.
The failure of the intermittant could either be due to a break down in the wiper control switch which is a series of resistors which might fail as it warms up OR again it could be due to a problem in the body computer.
So because the body computer is involved in both problems I would lean toward that being the culprit, but it is more expensive than the relay and the wiper switch cost, so you want to try and find out which alternative is correct.
You might take a look at the two (or more?) multipin plugs at the body computer: remove each plug and check for dirt or water contamination that could cause short circuits; spray the plugs and their sockets with electronic contact cleaner from a spray can (available at an electronics supply store). If you have any leaks from your windshield onto the body computer that can result in "gremlins" like you are describing.
If that doesn't help then check the relay's function (is it closed all the time when pulled out of the socket?) and also the wiper switch's wire (dark green/red) to the body computer with a voltmeter to see if the resistor chain is failing (does the voltage on that wire change when the intermittant function ceases?, and if not then the body computer would have to be the answer.
I can send you the circuit diagram from the Haynes manual if you want to see how the circuit works, which will make what I am suggesting clearer. But I need to xerox and snail mail it to you because I don't have a document scanner.
Roland