April 10th, 2007


Wiper Switch

Wiper Switch Side, originally uploaded by drbrain.

The one thing I'm most dissatisfied with in my car is the windshield cleaning parts. The wipers have an interval switch, but no setting for wiper speed between "every once in a while" and "short delay" seems to make a difference, it seems to stay at "every once in a while" for most of the switch positions with an exponential ramp-up to "short delay". (The other problem I have is the washer fluid supply tubes getting clogged, I probably need to replace them outright.)

The easiest thing to look at was the switch in the dash, and I expected some of the contacts to have gotten dirty in their 29 years of existence. Instead they're perfectly clean. The contacts on the back of the switch box are still shiny, as is at least one of the contacts on the sliding switch, and there's a thin film of dusty grease for lubrication, but it doesn't seem to be interfering with the contact of the switches.

The switch is even simpler than I thought it would be, and instead of having a traditional potentiometer, it seems to use these long, sliding contacts to give variable voltages to the brains in the wiper motor.

I guess my next step in this will be to pull apart the wiper motor and figure out if there are brains inside it that trigger the interval behavior, then trace those leads back to the switch. I didn't count, but there are eight or ten wires running into the switch, too many to be mentioned in the wiring diagrams I have.