Q: The intermittent wipers on my wife's 1998 Dodge Caravan Sport seem to be possessed. After the first few years the intermittent feature only worked intermittently. We would have to switch back and forth between low speed and intermittent to get them to work intermittently. This was not a priority to fix, as rainfall in Surprise, Ariz., is almost nonexistent.

Now something new has happened - this is the possessed part. When you turn the wipers off, they come on low speed, and the only way to turn them off is to select intermittent speed. This even happens with the key off. Is this something I can fix?

A: Good job observing and explaining so clearly what your wipers do and don't do. This means the difference of not being able to help you versus being able to suggest two clear courses of action.

Your Caravan's wiper system is one of the more complicated ones I've seen - it required two cups of coffee and an Excedrin to sort through. I began by printing three sets of wiring diagrams, and using highlighting pens, shaded the desired electrical paths for low, high, park, and intermittent functions.

Visualizing the pathways through a multi-function switch, several relays, the body control module and motor park switch, I gained an understanding of how things are supposed to work. Then I applied your symptoms and tried to grasp how the odd behavior could be possible.

Your first problem, I believe, is caused by a faulty control switch. Whenever a load (an electrical device that performs work such as a lamp, horn or motor) can be made to work by jiggling the switch, wiggling a connector or smacking the device, the fault is almost always right there, at the spot you are manipulating.

The Caravan's wiper switch contains a series of resistors for each of the switch settings. Depending on which setting is chosen, a differing voltage is sent to the body control module, the boss of this and many other vehicle systems.

This is a clever design, used to minimize the number of wires needed, but is vulnerable to additional, accidental resistance occurring throughout the rest of the circuit after many years of use.

You may ask for a certain setting, but the body control module thinks you want something else. It's very rare for a control module to make a mistake; erratic operation is usually the result of a faulty input or load.

The wiper switch is part of the "multifunction switch," contained within the turn-signal stalk on the steering column. These are widely available. Used ones are inexpensive and new ones are as cheap as $50. Replacement is fairly simple, after removing the upper and lower steering column trim covers.

Your most recent problem should also be simple to fix, with either a new or used part. The only possible way for the wipers to function with the key off is if the wiper-on relay contacts are sticking - that is, failing to separate when turned off. This relay is located in the power distribution center, a fuse box located in the left side of the engine compartment.

Relays are remote-controlled, heavy-duty switches, and modern cars are full of them. Using a relay allows a small switch or computer to request a medium to large load to be turned on, without having to supply the working electricity.

Power comes straight from the battery, through a fuse. Relays also unburden the ignition switch from supplying working electricity to the ever-increasing number of loads in use today.

Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Readers may send him e-mail at under-the-hood@earthlink.net; he cannot make personal replies.