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First Things First

Did you check the fuse?

Okay, Sometimes It's Not That Simple








Putting It All Together >>>

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Motor Woes

Is that motor assembly bad? Before you trot out and spend money on a new one, there are a few things to check out. Get a schematic diagram for the wiper system and parse out how it works. Generally, there are a couple of different windings on the motor for high- and low-speed operation. These will be supplied, respectively, with 12 volts when the key is on and the wiper switch is in, duh, high or low. Start by back-probing the connector to the motor to see if the 12 volts are making it that far. If so, pull the connector off and look for corrosion on the terminals. Check the park wire as well.

Got voltage? You might have one of those wiper systems that switch the ground side of the circuit on and off (which I think they do just to screw with my head). In that case you'll see voltage everywhere, even when the wipers are turned off... Back to the schematic.

As a last-resort diagnostic, jumper 12 volts directly from the battery to the appropriate pin on the motor's power connector. If there's still no sign of life, it's time for a new motor. Before you unbolt the old motor, detach the transmission linkage, which may have nice, plastic ball-and-socket joints, simple pins with nylon bushings and E-rings, or some other arcane method of carrying the motion across the car to both wiper arms.

Putting It All Together

Reassembly should be straightforward. Lubricate all moving parts, using silicone grease on rubber pieces. (Avoid using petroleum-based grease on rubber parts—it will deteriorate them.)

Some wiper arms have a friction fit to the wiper post. To position the arms correctly, briefly cycle the power to the wipers to park them. Now attach the arms in their correct at-rest position. Other wipers have splines that mate in only one position, so if the arms don't rest properly when parked, you'll need to adjust the linkage elsewhere, probably at the middle pivots.

How It Works: Self-Parking Wipers

Generally, the motor assembly is one of those things that have no user-serviceable parts inside and is inexpensive enough to make attempted repair pointless. If you have trouble finding a part for an oddball or collectible car, it may be worthwhile to open it up and poke around. Or maybe you're like me and just prefer to know what went wrong. The worm gear spins the ring gear as long as it's powered. When the switch is turned off, power continues through the always-hot park contacts—the two fingers that rest on the copper ring—instead of directly from the wiper switch.

There's a gap in the copper contact ring. As the ring spins, the park fingers drop into this gap, breaking the circuit and stopping the motor at the same spot every time. If you shut off your wipers and they stop immediately at some random spot on the windshield, the park contacts are probably corroded or broken. A sousing with contact cleaner and a little touchup with a typewriter eraser should restore normal operation. Be sure to relube the gears before buttoning up.

What do you think?