On my 1968 BB,427 I can only get my wipers to work, when I open the wiper door by the manual by pass **** under the dash, once door is open the toggle switch on the dash works fine On-off-low-high speed.What to look for ???

 

Make sure the solenoid under the tach is plugged in and working.
edit- Uh oh you have a 68 where is Willcox ?

 

Ok I just looked at Willcoxs vacuum diagram of the 68 and if the pulldown bypass will raise the door then the solenoid will also providing it is working.
I'll go see if I can find a 68 wiring diagram so I can see what operates the solenoid.

edit - it appears that the solenoid has 2 wires 1 is a black ground and the other is a brown that must be hot to operate the solenoid. The brown comes from the wiper motor. If the brown at the motor is hot and the ground at the solenoid is good then the solenoid could be bad or the vacuum side could be plugged up. Your solenoid should have only 2 hoses going to it and the 3rd nipple should be open so the vacuum can vent.

 

it does sound like your wiper control is not opening the door.
the door must be open to make electric flow to motor.
safety feature.

 

That definitely sounds like a solenoid problem, or a broken wire to the solenoid...does your car have an aftermarket radio?

 

No it has the original radio, and it does work.

 

Where is this solenoid located? under dash or in engine area ??

 

its mounted on the back side of the tachometer, cant miss it...it has vacuum and electrical lines going to it.

 

I find most of them unmounted and hanging.

Lilfur is this a new problem or was there work done that could have caused it ?

 

Cooking. . . Cooking jalapeno, chicken, and bacon poppers for today’s party!

I think most of this has been covered, but if the over ride is working the wipers, it appears that you have a problem with the tach solenoid.



The function on the solenoid on the “1968 car only” is to block vacuum to the wiper door actuator relay. When the vacuum is blocked on the small hose at the relay it will then go in to the open function. What it appears you are doing is blocking this vacuum with the over ride switch instead. Please note: This entire system is different from the 1969-1972.
As Dwnnchs mentioned above, you have a brown power wire that supplies power to this solenoid. You also have a black wire that supplies ground. The brown power wire is only made hot when you turn on the wipers motor switch.

Pull the connector from the back of the tach solenoid, turn on the wipers and probe the brown wire for power. If you have power when the switch is turned on, then check the black wire to see if you have ground. This is the easy part. . .

If you do not have power or ground repair them and test again. If you do have power or ground then you need to test the solenoid. The solenoid should block vacuum from passing thru the system as described here:

The solenoid or solenoid wiring is probably the problem and should be an easy fix.

Willcox Inc.

Pages you might want to look at:
Wiper and Headlamp parts and how the function This one tells you how to test the solenoid.
68 wiper motor help and repair

 

Dang Willcox that is some fine customer service now if you will just invite us all over for some of that chicken you will be #1 in my book.

I would like to add one little thing. Obviously vacuum is making its way through the solenoid and as Willcox said the solenoid must block the vacuum but then it also must "dump" the vacuum in the hose on the overide and relay side of the solenoid. As you can see in the pic of the solenoid there is a nipple that is covered in foam,that is the vent or "dump" for the vacuum. It has to be open and the hose has to be on the correct nipple which is illustrated in the Willcox drawing. OK I'm done back to salivating over the chicken.