wipers not working - troubleshooting time

[Mattrix]

Hey all,
Loving all this rainy weather we're having, especially since my vette wipers don't work. Not sure what happened, one day they worked, not they don't. Don't even know where to start in troubleshooting the issue, can't figure out where the problem could be. Have checked the fuse, it's fine. So, short of just buying a new wiper motor, how can I go through and work out if that is the problem or if it's something else entirely?
Thanks
Matt

[gtc]

I don't have the wiring diagram for your model, but a wiper circuit is basically: battery (via ignition switch) -> fuse -> dual-speed switch -> dual-speed motor - > earth.

So, if battery and fuse are okay, then that leaves switch, motor and earth to check.

If I were a betting man, I'd back bad earth or bad switch before bad motor.

In order to do some continuity checking, you need to work out which wire is which on the motor.

I'd use an ohm meter to check that that the motor is getting a good earth. If so, then I'd next use a volt meter to check the switch by seeing if the motor is getting 12 volts in each position.

(Alternatively, some wiper systems have battery on the motor and the motor gets earth via the wiper switch. Again, I don't know which way your model is wired.)

If the switch checks out okay, then it sounds like the motor, and it could be its wiper-park contacts (... or something else). However, before shelling out for a new wiper motor I'd get it checked by an experienced autosparky.

[bfit]

Matt what model car
I have some literature   to trouble shoot  early C3
Bfit

[sirfixalot]

Matt you have u2u.
Most auto elecs wouldnt know where to start, corvette designers had one two many smokes when they designed & wired wipers

[bfit]

Matt its quite simply if you can read a wiring diagram
Unfortunately all the diagrams I have seen a poorly recreated when drawn
 A multi meter is a must don't get a cheap one
You will get cheap results
 A good one will last you and you a life time.
If you under stand V/IxR  (Volt=V, current = I.resistance =R )  form your school days
You will have no problems (well  they will  not be to difficult )
The main problem with the vette, that I found IS
Finding where all the wire originate from and where it  is where in the vehicle
But asking question here helps some one will have already done what you need to do
 I do know that  in the 69/73 that the motor works  like this
 power is supplied to the center contact of the three
the speed is controlled by the two  earth  contacts
  I can look up the colour code for you if your model in in the range
Bfit

[bfit]

Matt you will get help here  as well
Australian Corvettes Association
http://www.australiancorvettesassociation.com/phpBB//index.php?sid=07b581072a72c957f50e57fa2c0eb875
Bfit

[bfit]

I had to go an check the formula above,
  its been  long time since my school days
Bfit

[sirfixalot]

Check to see if you have a positive on centre terminal of wiper motor  with ignition on if so then run a temporary earth & insert into either top or bottom terminal, motor should run.If no positive at motor check under column at isolator switch( if applicable) if power on both sides of switch, the next point to check positive is at micro switch for wiper door( if applicable).Depending on year model early C3 needs 2 positives to motor the heavy red single wire which comes from micro switch & goes into side of motor &  also a positive on centre teminal.
Next test connect test lamp from positive on alternator then connect other end to either of the external terminals on 3 pin plug & operate switch in car lamp should lite when switch operated.
If you have both positive & negative tests ok fault is in motor it will be the small white relay block located under spade connectors in motor.Motor has an internal relay for park mechanism the contact goes open circuit.This part can be replaced
 

[Camo]

May or may not be of assistance.

Following for a 77 Corvette.

Best I could do with an A4 scanner scanning A3...

Click Images For Larger Views

[Mattrix]

Awesome work guys! In a strange twist of fate, I was driving along the other day with my good luck charm (that being my new girlfriend, who seems to live a charmed life), and the wipers came on by themselves! They only ran till I turned the car off, but it was long enough for me to get the notion that the motor was OK.
Anyway, I pulled the wires off the back of the motor, and cleaned up the terminals. Lo and behold, they sprang to life. So that just makes one less headache for me to deal with (plenty of others though, such as leaking auto trans, air in brakes, driver door lock keeps playing up, front windscreen leaks, etc etc).
Thanks plenty for all your input!

[sirfixalot]

I had the same problem going to Queensland convention a few years ago wipers were working fine when we left home then the heavens opened up & they decided they were allergic to water
about 100k on they started working again eventually tracked the problem to the contact in park relay inside motor was intermittently open circuit