Homework help needed

[Marvin]

Hi ,
hope someone can help us, trying to help my son understand fault finding proccess in a wiper motor. We seem to have the gist of it but are struggling to find how to check if the wiper park switch is faulty, can anyone help.

many thanks in anticipation

Steve

[Dangerous Dave]

From my experience with my old Renault, if the switch is faulty when you turn off the wipers the wipers will stop in the position they're at (anywhere on the screen). Not sure if this relates to a Volvo as I've never had any problems with the wiper motors on them.

Any more details on the problem?

[Marvin]

Its a college question he has been set on how to diagnose a faulty self park switch on a cars wiper motor, if its old it seems easy enough ie a seperate switch, if its modern read the fault codes via the ECU. The problem is if its a electronic type sealed within the wiper motor how do you confirm the fault?

[nobananas]

I'm no auto electrician but I usually get all the 'sparky bits that don't work' to sort out where I am. On older stuff there will always be a permanent live to the motor which is there for the self parking and a switched live that comes from the switch gear (or possibly a switched earth to if it's ecu controlled). There will also be an earth. If the permanent live has failed then the wipers will stop anywhere when they are turned off, if there is a problem with the self-parking switch then a similar thing will happen but the permanent live will still be present. (that probably won't be much help to you !)

[Marvin]

Thanks for the contributions its helping us to direct our thinking. Its been a long time since me and his mom was in school, and I hate to admit it but I made the decision some years ago I was to old to lie under cars in the rain and damp anymore.

[Dangerous Dave]

Another way to do it would be to test the park switch wiring with a multimeter. Turn on the wipers and see if a voltage is present/not present when the wipers should be 'home/parked'

[glock19]

Hi ,
hope someone can help us, trying to help my son understand fault finding proccess in a wiper motor. We seem to have the gist of it but are struggling to find how to check if the wiper park switch is faulty, can anyone help.

many thanks in anticipation

Steve

If this is still unanswered :
You'll need a 12V test light.
- Test the lead at the positive end of the switch, Test light should come on
- If not, check related fuse.
- Turn the switch on and use the test light on the other end of the switch. The test light should be lit
- If not, then switch is questionable
- If both the switch terminals are okay, then use the light at the socket to the wiper motor.
- If there's light there, then motor is gone.

Now the above is mostly for wiper motor or some other electrics not govern by the ECU
Radiator fans, air-cond compressor, etc are driven by the ECU on the negative side.
So when using a test light, there will be power on both side of the connector until the switch is turned on, the the test lit dims.

It's good the question was about wiper motors, otherwise it's going o be a tough nut to explain.