77 C10 Windscreen Washers

[AussieC10]

Hi - I been reading the forum for sometime and this is the first post.  Hopefully someone can help.  We have a 77 C10 that has been converted to R/H drive but it still uses the standard wiper motor and washer setup.  The washers failed and we purchased a new washer assembly from the US and once fitted the pump part works great but the pump starts and runs whenever the wipers are turned on irrespective of whether or not the washers are activate.  A visual inspection of the new part compared to the original Chev part shows no discernable differances.  Electrics check out OK and seem to be doing what they are supposed to.

Has anyone else experience this problem and has a fix?

Ian

[bake74]

     Welcome to the site, sorry I do not know what it could be if the electronics check out and you said the part is the same, someone will chime in give it some time.

[Captkaos]

What year truck?  What kind of wiper originally?  Delay or not?  Sounds like it is getting power all the time and something is wired wrong.

[AussieC10]

Hi Chris - the C10 is a 77 stepside.  Because of the R/H conversion it is also a problem to ensure the parts are from the same model.   The wiper motor/washer assembly is standard (or so it seems) for that model and the replacement washer pump is straight from the   truck catalogue and looks identical to the Chev part we took off.   However no guarantee that it is.
I have checked the electrics (by the way thanks for having the wiring diagrams on the site).   The way I read the circuit is that power is to the solenoid all the time and it is activated by a momentary earth closure at the wiper switch.   It is not a delay wiper assembly (more the pity).
I've spent hours trying to sort it out and I suspect the problem is with how the solenoid interacts with the mechanical assembly of the pump.
The backup plan is to install an aftermarket pump and washer system that I have but that's not the same as trying to keep it looking reasonably genuine.

Cheers Ian