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Detailed Introduction on Wiper Motors

By Elina | Published on Dec 09,2015


Windshield wipers are responsible for keeping your windshield clean and dry in adverse weather conditions. When you pull the lever on your steering column to activate your windshield wipers, the windshield wiper motor begins to spin. This motor powers the rubber windshield wiper blades, which run across the windshield and remove any water and debris. When the windshield wiper motor dies, there will be no power to the windshield wiper blades, and they’ll stop moving. As a result, your windshield will not be cleaner or dried off, and you will have virtually no visibility if you are driving in the rain, snow, or dust.

A windshield wiper consists of a pivoting arm with a long rubber blade. The wiper motor is an electrical device that moves the wiper blades automatically for better visibility in all weather conditions.


Using a cheap OFF/ON/ON toggle switch and a relay (Hella 3057 12V 40/15A) it’s relatively simple to get both wiper speeds and the wiper auto park to work. The switch I use looks reasonably close in appearance to the original Lucas dashboard switches. I didn’t have a spare headlight switch to try with this circuit so sorry folks, I can’t tell you if it would work or not. (If anyone does try this let me know and I’ll update these notes accordingly.)

I solder all of my connections, covering the joints with heat shrink spaghetti, then for neatness finish by binding up the wiring with electrical tape. I have a pet hate of those quick crimp wire connectors as they can corrode and cause poor electrical connections.


On first inspection this circuit looks like it can’t work, but does as you’ll see in my explain a little later.

I’ve tried to include the wire colors that appear in the workshop manual wiring diagram, if you can get part of the original wiring loom with the wiper motor, this makes it easier.

RLG – Red Light Green, NLG – Brown Light Green, ULG – Blue Light Green, GK – Green Pink.

Also note, I haven’t drawn the Wiper Motor connections in the above diagram as they actually appear on the motor (as a double row), but instead to make the above diagram easier to read.

The pin connections on the Wiper Motor are as follows:

Flicking the toggle switch to the first position (slow operation), power is applied to the relay, closing the contact and supplying power to pin 5 on the wiper motor (via pin 87 and 30 on the relay). The Auto Park connection on the Wiper Motor (pin 2) is not connected to anything while the relay is energized.


The fuse is okay, or you've replaced it with one that has the appropriate amp rating. There's still no action? With the wipers and ignition on, whack the motor assembly with the handle of a screwdriver or a rubber mallet. If that gets things moving, you've got a bad commutator or an open winding on the armature. When the motor parks, if the brushes are sitting on the bad segment, no current flows. Whacking the whole business smartly can sometimes jolt things into motion. Because there are often a dozen windings on the armature, the motor runs fine until the next time it comes to rest on the bad spot.

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.

A favorite friction point is the bearing surface between the wiper shaft and its mounting block, which is often nothing more than a steel shaft running through a whole cast in plastic. A corroded steel shaft can swell up and bind. It's not a bad idea to dismantle the mechanism, wire-brush off any corrosion and reassemble the whole thing with a generous dollop of silicone grease.


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