Windshield Wiper Repair

Windshield Wiper Unit Rebuilding!

Among many other things windshield wiper was not working when I got this car. Later I found out that this wiper unit had several issues.

Initial Trouble Shooting.

• Always check the fuse first! Then I used multimeter to find out if the power is coming to the terminals. I labeled wires, then check for power after removed them from terminals. By turning the switch on several places I found three wires for the power, one for slow, one for fast, and one for off position (to return the wiper to down position.)

• Check for the ground. Put one end of test lead on the body of the wiper motor, other end to known good grounding point of the car. No electrical connection between them. (From my personal experience about 70% of electrical problem was caused by poor groundings.)

• I put a jumper wire across the wiper motor to grounding point. However, it still doesn't work...

Removing the wiper assembly.

Now it's time to pull the wiper unit from the car. It can be accomplished by. 1. Remove the wiper arms by loosen the setscrews by the wiper shaft. 2. Remove the small bolt that attaching motor unit to the body under the dash.

• Remove the nuts from each of wiper shafts.

• After this wiper assy should come out with little twisting and turning.

Removing the motor from Wiper Assy.

• Remove the push-pull rods from the crank by carefully removing a clip. (don't lose it!!!)

• loosen the nut on the center shaft, and remove another small bolt that holding motor to the support.

• Slide, twist, turn to remove the motor.

• Open the gearbox by removing screws on top.

• Turn the motor upside down and remove the motor cover by pulling the wire clip.

• Open the internal switch cover by removing two little screws by terminals.

Testing the motor

• Check the continuity between the terminals and the brushes.

• Check the resistance between + brushes and Ground. I got 3 ohms or so, which sounds ok. Turn the motor by hand and look for short circuit and large dead spot. (very high resistance or open connection) If you have a large dead spot one or more coil may be bad.

• Get a 12V power supply. I used a small battery charger.

• Connect - terminal of power source to the body of the motor.

• Contact + side of power to the one of + terminal.

When I did it I saw a light! Well, actually a little spark and red growing copper on the commutator of the motor. I removed the power immediately. After the brief investigation I found that metal dusts has been collected between the commutator and producing partial short-circuit.

• Clean the metal dust on the commutator.

After cleaning the commutator motor tested good.

Testing the Internal Switch.

Internal switch is used to return the wiper to down position after a driver turned switches off. It is located behind the terminals, and actuated by small push rod and the cam on the reduction gear.

• Connect the test leads on each side of contact, and turn the motor by hand, to see if it open and closes.

• Mine was stuck at open position, because of sticky old grease. So I pulled the push rod (don't lose it!) and cleaned old grease on the gearbox.

Re-assemble and test again. Yes, it works!

Re-installation.

The assembly works, but I need to figure out about the grounding problem. What I did was sanding small amount of paint off from the tab under the dash, then install a bolt using a star shaped lock washer. Multimeter showed less than 0.3 ohms after the installation.