C3 wiper troubleshooting (continuing story)

[Rob M.]

We are still struggling getting the wipers working. We have removed a blockade from the wiper engine since the part showing on the picture was preventing the motor to run. We tested the motor and it seem to work fine now. When reinstalled in the car we ensured the wiper door switch was properly working when we manually opened the door. The check valve on the wiper motor is clicking when the wiper switch is switched. The wiper valve near the right wiper is hissing a bit and needs to be replaced. Outstanding questions:

1) Why is are the wipers still not moving (the wiper motor is not started when the switch is operated although the check valve is clicking)?
2) Does anyone where to by the faulty bit displayed below?

thanks for your help,
Rob (and Sander)




C3 weblog !!!

[Jack H.]

Re: C3 wiper troubleshooting (continuing story)

The early Shark wiper door system is a bit tricky, but once understood, yields to pretty simple troubleshooting efforts. Its operation is covered in the Chassis Service Manual for the year car you're working on, Rob, repleat with a good theory of operation thumbnail.

There are two systems: mechanical/vacuum and electrical. They inter-relate for the system to function properly. When you throw the wiper switch on the instrument center cluster, you apply power to the WSW motor as well as to the vac relay mounted on the back of the tachometer. The vac relay opens and vacuum is allowed to move the wiper door actuator causing the door to open.

When the door opens, it presses against a micro switch mounted on the RH firewall. This completes the power circuit from the battery to the wiper motor. The micro switch is a safeguard to prevent the wiper motor from actuating the wiper arms before the wiper door is safely up and out of the way.

You should be able to trace the flow of power to the micro switch, out of it when the door actuator hits it (mech adjustment here) and on into the motor. The leads to the micro switch are red/white and the power into the motor is on a single red wire with in-line connector. Verify power makes the full routing as it's possible to have bad/oxidized terminals at the micro switch as well as at the in-line connector to the motor.

Last, next to the single red wire on the wiper motor is a single black wire. This is the motor's return ground. Since the motor is installed on non-conductive fiberglass, it HAS to have a discrete ground to work. Verify both the power lead and ground connectors at the wiper motor are functioning properly and your problem(s) should evaporate.

Hint: the side of the horn relay on the LH inner fender is the engine compartment's B+ power buss. It's always hot regardless of ignition switch. You can jumper from the side of the horn wire directly to the wiper motor's power terminal (WITH the wiper door opened manually!!!) to FORCE the motor to run....

Last: there's a manual over-ride switch (round black button) beneath the steering column in the cockpit. This is used to manually STOP power to the wiper motor to facilitate changing wiper blades. Sometimes, new owners don't buy/read the owner's manual and the 'failure' of the WSW motor to run is simply a cockpit problem as they've got the over-ride switch in the wrong position.... Rotate the switch toward the passenger seat to put it in the standard 'run' position!

On 'hissing' you hear, the whole system works by VENTING vac to make things open/move. So, you SHOULD hear 'minor' air flow noise when the system is in use. That's one of the reasons you'll find a 'loose' hose going through the wiper door grommet into the engine compartment on the RH side...it's the wiper relay's vac vent line and it's INTENDED to vent vac beneath the hood.

On this same subject, the system needs to know WHEN the wiper arms have safely stopped moving and reached their final rest position before the wiper door can be closed. There's a vac relay on the RH side beneath the wiper door that the RH wiper arm pushes against when it parks. This creates the vac signal to go ahead and shut the wiper door. The screws that mount the relay allow it to be adjusted (up/down) and 'fine tune' the final wiper arm rest position as well as when the wiper door should start to close...

On the 'Nautilus' gear that drives the washer assy, it's the same piece as used on virtually every passenger car/truck WSW washer assy from the era. They're a dime a dozen at scrap yards (BUT, you're in Holland).... Contact me off-board if you want me to hustle one up for ya!

[Rob M.]

Re: C3 wiper troubleshooting (continuing story)

Hi Jack,

Thanks for this extensive explaination. Just a few questions outstanding:

1) What is the order of the air hoses on the wiper valve ? I've got a red, white and none marked hose.
2) Does anyone has a scan available of the complete air tube setup of the wind shield wiper and headlight door setup also indicating the color of the tubes. If so please mail me this so I can work out my current problems.

thanks all as always,
Rob.




C3 weblog !!!

[Jack H.]

Re: C3 wiper troubleshooting (continuing story)

When your car was re-painted, they didn't take precaution(s) to mask the wiper door cowl area and, as a result, you've got TONS of body color overspray obscuring components.... The wiper door safety switch was originally color coded at its nipples to prevent improper hookup. But, that info is now 'history' due to the painter's laziness....

I'll talk you through it. The upper nipple of the safety valve is the vent hose (basic black, routes back into the engine compartment and is left disconnected). The middle nipple of the safety valve routes into the cabin and eventually connects to the wiper door vac over-ride switch beneath the steering column (can't remember color coding). The lower nipple routes into the engine compartment and connects to the wiper door actuator relay.

Folks like Dr Rebuild, Mid America, and others sell vacuum system troubleshooting phamphlets and some provide color coded 'vacuum schematic' diagrams. BUT, these products are copyright protected, so it's not possible to simply post or 'squirt' you a copy without violating the law and their IP (intellectural property) protective rights.