on my 72 im having issues with my wipers the door works with the override but not with the wiper switch nor does the wipers but when you turn the knob between the two vacuum overrides the wipers move then return to rest, also when you take the wip[er switch out and leave  it pluged in it sparks or grounds out when it comes in contact with the bezel (only in the on position) is there a reay or selenoid bad or what     please help

The round knob in between the two over-ride valves is to turn the wipers OFF/On, so you can change the wiper blades. The push/pull knob will open/close the door, but will not effect the wiper operation itself.

The wiper switch MUST be grounded to work...that is why you see sparks when you touch it to the bezel...it should be grounded to the bezel. A lot of folks will run a dedicated ground wire to one of the screws that hold the switch to the bezel, to make sure the switch is properly grounded.
If you bezel is not getting a good ground contact when it is screwed to the dash, it can cause wiper problems, which is the reason for the dedicated ground. So...make sure the switch is grounded, and be sure the wiper "Stop" knob is turned to the correct setting. The "Stop" knob will allow you to turn the wipers on, and turn the knob to stop them in mid-swipe, so you can easily change the blades. If the knob is inadvertently turned, then the next time you want to use the wipers, the door will open, but the wipers will not move. More than one feller has spent hours diagnosing a wiper problem only to discover the knob had been turned!
hth

ok i understand that portion but when i turn the wipers on and everything is hooked up (nothing taken apart) nothing happens i have to pull the door override for it to open what tells it to open when the wiper switch is turned on the override is just that an override not the operating switch could the ground at the switch be causing that malfunction as well  thanks for the input

Yes, the switch not being grounded could cause this. I can e-mail you some troubleshooting info on the wipers that might help. I'll do that here in a minute...

thanks for the vacuum giude i hope i get some free time this holiday weekend to check things out   merry christmas

The only thing to add is that the wiper switch first activates a solenoid valve behind the tach, which opens the wiper door.  The wipers won't try to fun until the door is wide open and hits the switch.  If the ground is good, but the door still isn't opening, it might be the solenoid valve, or the wiring or vacuum tubing going to it.

Larry

I thought about that, too, but...the wipers should function with the door over-ride in "Open", no?(assuming it does open all the way) I sent him info on how to test all of that stuff, including the hidden solenoid from h ell...
It'll proly wind up being the "park" switch out of adjustment, or a ground problem somewhere. Imagine that...a ground problem in a Corvette?!
Adams' Apple2009-12-28 11:53:25