Saab 9-5 Wiper Motor Repair

Ever sit there in the car with the snow and ice about a foot thick on the windshield and wonder, "What would happen if I turned on the wipers?". Let me save you the trouble: they remain motionless, emit a last gasp of burned-electronics smoke and stop working properly. Since I conducted this experiment and am now writing about it, you don't have to.

If you are like me, a little impulsive, maybe you just have to see for your self. Or maybe you just don't believe that car manufacturer could be so silly as to not think through this particular use-case and produce a design which would be immune to it. Either way, you are now sitting in a Saab 9-5 sampling the distinctive odour eminating from under the hood and trying to decide if it smells more like vaporized copper or silicon/epoxy.


Here's what I did about it. Easier and cheaper than inventing a time machine to undo the deed, though perhaps less interesting.


Phase I: Get the wiper motor out of the car.

From the Haynes manual, section 12-15:

1. Remove the wiper arms (M15 box wrench).
2. Remove the rubber seals around the wiper arm spindles, then remove the windscreen scuttle (the wide plastic trim piece at the foot of the windscreen). (#2 Philips)
3. Remove plastic cover partially occluding the wiper motor assembly.
4. Disconnect the connector from the wiper assembly.
5. Slacken the four bolts securing the wiper assembly and remove it.
6. The wiper assembly consists of a four-bar mechanism driven from a crank arm by a single motor. Mark the position of the crank arm relative to the shaft it is secured to. You will need this information in order to re-assemble without testing/calibrating the position of the crank arm.

The wiper motor assembly should look something like:

Phase II: Fix the motor

Depending on your time/money ratio, you may simply wish to replace the assembly. If you decide to repair it, here is what I did:

1. Remove the nut holding the crank arm on to the motor shaft; separate the crank arm from the motor shaft.
2. Unscrew the three bolts securing the motor to the mounting plate, and remove the motor. (M10 Socket)
3. With great difficulty, remove the rubber boot from the motor.
4. Remove the four hex-head machine screws holding the cover onto the gear box.
5. Observe the damage: hole burned in output shaft gear, contact burned beyond recognition.

6. You are going to need to fill that hole with something, and when finished it will need to be smooth in order not to catch the contact as it turns. Start by grinding out the burned plastic to create a purchase for some 5 minute epoxy.
7. Clean the area with compressed air.
8. Pour 5-minute expoxy into the wound, making sure to remove air bubbles.


9. Wait 90 minutes for cure.
10. Mill off the excess epoxy using a dremel and one of those magical dremel end-mill cutters.

11. Fashion a new contact in the shape of an undamaged one out of some phosphor-bronze of appropriate thickness (usually found in relays, switches, etc). I used an old Saab door switch contact.
12. Reassmble the motor assemby.
13. Test with meter and battery. Red and white are motor terminals, contacts are the three wires going to the plastic plug on the gear box cover. Check that the middle contact makes a connection with the outer contact and breaks the connection with the inner contact when the motor reaches the "home position".

Refiitting is the reverse of the instructions in Phase I.