Awhile back I posted regarding my '70's defunct windshield wipers, and got several useful answers regarding how to troubleshoot the problem. I tested all the circuits according to info provided by the nice folks at Willcox and so far the system seems to have juice everywhere that it's supposed to have juice but still no wipers. Initially the wiper door opened and closed as advertised but that was it...wipers just wouldn't come up. I finally got around to removing the motor (something of a PITA in itself) and tested it on my workbench...lo and behold everything was working just fine per Willcox's YouTube video so back on the car it went. However, in the rather delicate process of re-installing it a wire that was attached to this little module mounted on the firewall came adrift. It's mounted to the firewall next to the wiper motor on the driver's side and has three wires going to it- one turquoise, one darker blue on a common connector and the other one (which broke off) a darker color (purple or black) having its own single connector.
After reinstalling the motor I hooked everything back up, started the car, and tried to run the wipers. Again, nothing, only this time the wiper door won't even come up. The only thing different between this time and before is that little module on the firewall which leads me to believe that it sends juice to a relay that sends vacuum to the wiper door actuator. Problem is, I can't find it anywhere on my factory schematic and I don't really even know what it's called or what it actually does so that I can order a replacement. Could somebody out there give me a clue as to just what this thing is, what it's called (so I'll know what to order), and what it does?

 

That's a TCS relay and shouldn't effect the wipers unless someone has done some weird stuff with the wiring.

Try this if you have a standard 12v testlight , manually open the wiper door, check the red wire coming out of the side of the wiper motor for power, if power is on the red then check 12 yellow in the 3 wire connector, if you have power on the yellow touch the testlight to the light blue next to the yellow (like in the pic),9 times out of 10 the wipers will run using the testlight as a ground. (if the testlight won't run the wipers then use a ground wire in place of the test light)

 

Hi,
Is there ANY chance the wiper switch under the steering column is turned????
Regards,
Alan

 

That was my first thought also Alan but I'm guessing he is familiar with the black shut off ****,unless he forgot about it. Here is a thread of his with more info.
http://forums.corvetteforum.com/c3-t...motor-bad.html
I have a suspicion his dash switch is ungrounded.

 

Hi guys..

Roger might be correct on this. A simple jumper from the wiper switch to ground would answer that question. If the dash bezel is broke in half, then he will need to run a jumper ground from the switch screw to the back of the gauge housing.

He needs to make sure the switch under the dash is on. Make sure the red wire at the limit switch has power and make sure he has 12 volts on the yellow wire and verify the motor ground! All quick and simple steps... then move on to the switch in the dash.

Wonder if he's seen the help section on the motor with the wire schematics and help steps?

Ernie

 

Hey guys-

Thanks for the replies. I've been working some long hours with little time to get to the vette lately so I haven't acknowledged any replies until now. Thank you for the info on the TCS switch Roger; I've long since dispensed with the TCS (still have it in a box in case I have to answer to the CA smog ***** though!)so I guess I'll have to do some more investigating to see exactly what I did to kill my wiper door. I am well aware of the shutoff switch under the dash and have tried the system with the switch in both positions to no avail, and the door won't come up now with the override switch either. Either tomorrow afternoon or Sunday I will check power to all the various places again; I'm thinking it may be that the ground wire that attaches to the case is bad as well. When I originally tested the system I used Willcox's diagram (thanks Ernie)...all the wiring is original and has not been butchered in any way, but the poor girl sits a lot these daze and I'm thinking the ground may have just gotten a bit fossilized...

 

OK, here it is. I tested power to the wiper door override switch, and that was good, so I removed the switch and bench tested it. Readings seemed kinda iffy between "off" and "on", so I left the switch off and bypassed the connector with a jumper wire. Took out my vacuum diagnosing paper and began checking vacuum back through the circuit, and when I got back to the actuator can I noticed that the flange of the internal diaphragm was loose. I have no idea how it got that way, but I pressed it back in and now my wiper door works like it's supposed to again (??). I then reattached the override switch and everything still operated correctly (at least as far as the door is concerned...).
I then began trying to troubleshoot the motor. With everything just plugged in like it's supposed to be I still had nothing, so I decided to try and ground the tab on the case direct to the engine-no change. I then checked power to yellow #2, and it did have power always when the ignition was "on". I then pulled apart the connector to red #13, and IT had power as long as ignition was "on" and the wiper switch was on, so it seems to me that power is going where it's supposed to go when it's supposed to go there. I then tried jumping blue #3 direct to the engine while I jumped the 3-wire connector yellow wire to the power tab on the motor...switch "on" in either position, still nothing. I then tried jumping from the center (yellow#2) terminal on the connector to the case ground wire, and ground was good. Lastly, I also tried juping my meter across yellow #2 and blue #3 at the connector, all good.
What this all seems to be telling me is that the motor somehow HAS to be bad, but I've tested it numerous times on my workbench using Willcox's YouTube video as a guide and everything works exactly as it's supposed to (??!!?!?). I also tried it both with and without the washer solenoid wires connected to the front of the case, I can hear a clicking sound when I turn the wiper switch on but I don't think that should affect wiper motor operation in any way (should it?). Everything that's supposed to be getting power is getting it when it's supposed to get it, and all the grounds are good...any ideas??

 

JUST TO CLOSE THIS ONE OUT...in desperation yesterday after my last post I went ahead and pulled the wiper switch down and away from the bezel, operated the switch, and VOILA! WIPERS!! A couple years ago I replaced my cracked dash top with a new piece from Corvette America, and apparently its slightly different-shaped underside was bending the connector down somewhat enough to cause the switch not to work properly...after fiddling and tinkering with it for awhile I was able to close it back up and still retain operating wipers. Thanks for all the advice from all of you who took the time to post suggestions...if I had been following ALL of your advice from the start I'd have a few less gray hairs right now!

 

Good deal! I did not get on yesterday so I missed your other post...

Glad you got if going!

Willcox