I am learning here.....on the C3's 68-72.....do the headlights and wipers work with same override switch? I am going to inspect a 70 coupe that the seller say the wipers don't work. I would be thrilled to see if this switch has been activated.

 

The vacuum system always fail to the safe position so when the signal vacuum is cut off the HLs open and the wiper doors open so they can be used.

 

I accidentally clicked on something and messed up my original post,..but...

So, if the wiper door is now open (engine off, key off) and the switch has been "activated" the headlights should also be popped up, correct? Well, my view of this car is the wiper door up but the headlights are still down.

 

The headlights and wiper door have separate override switches.

 

In a word, no. There are separate overrides for each system.

Very common problem with a car that has been neglected or the wiper system is misunderstood. Once you understand the operation of the components it's an easy fix. If you like the car, act like the wiper door is a BIG problem and get the price of the car down.

 

Headlight switch - located to the left of steering wheel.
Wiper switch - located to the right of the steering wheel, center console above gauges.
Headlight vacuum override switch - located under steering column, left side.
Wiper door vacuum override switch - located under steering column, right side.
Wiper motor electrical override switch - located under steering column, center.


Try these steps when looking at the car,

Headlights - with the car off, from underneath the front of the car, reach up and pull the headlights down. You basically pull the headlight hinges over center and close the headlights.
Start the car, turn on the headlights using the headlight switch, just pull it all the way out. The headlights should turn on (electrically) and pop up from the vacuum.
Turn off the headlights, push the switch all the way in, headlights should turn off and retract.
Now try the headlight override switch, located under the steering column (it's the **** on the left), pull it down, the headlights should pop up but will be off electrically. Push the **** up and the headlights should retract. The override switch should be pushed up for normal every day use.
Depending on what happens, you can have various vacuum issues.

Wiper door - with car running, try the override switch, located under the steering column (it's the **** on the right), pull it down, the wiper door should pop up. Push the **** up, the wiper door should close.
The override switch should be pushed up for every day use.
If this works, try the wiper switch. With wiper door down, turn on the wiper switch, the door should pop up and the wipers should work. Turn the wipers off and the wipers should park and the wiper door should close.
Depending on what happens, you can have various vacuum issues.

There is a third round **** under the steering column (located in the center) that controls electrical power to the wiper motor. This **** turns approximately 1/4 turn. If the wiper motor does not turn on using the wiper switch, try turning this **** one way or the other to see if it is in the wrong position, killing power to the wiper motor.

 

If you are familiar with how electric relays work, the vacuum system is just like an electrical circuit with a relay.

The engine vacuum is directed to two sides, the control side (the dash), and the actuator side (engine side).

On the engine side the vacuum goes to a storage tank (to hold vacuum with the engine off), and from there to the relays. The relays take the source vacuum (yellow), and direct it to either the down (red), or up (green) side of the actuator. The small control (white) vacuum line into the actuator control whether the source is sent to the up or down side. When the control has vacuum, the source is sent to the down side, when there is no vacuum on the control, then the source is directed to the up side.

On the dash side are the conponents that either allow the vacuum to either flow through the control line, which will keep the actuators down, or to block the vacuum on the control line, and the actuator will go up. If you turn on the headlights at the switch, the switch blocks the vacuum on the control line. When you turn on the wipers at the switch, a signal is sent to a solenoid that cuts off the vacuum on the control line to the wiper relay. Either of the overrides when pulled in the down position cut off the vacuum on their respective control lines, and the their actuators go up.

There are a couple of additional components on the wiper system. On the diagram there is a safety valve, it has a plunger that is pressed when the wipers are fully parked. If the wipers are not parked, the vacuum is cutoff, this is to ensure that the wiper door does not close until the wipers have fully parked when they are turned off. Below the valve on the diagram there is a small black switch with a small white button. It's the limit switch, and it's in the negine bay, on the firewall, towards the center, and is behind some metal linkage. It's job is to keep the wipers from running when the wiper door is closed.

Basic function of the wiper system is, when the switch is turned on, power is sent to the solenoid, and the wiper limit switch. The solenoid cuts the vacuum on the control line and the relay redirects vacuum to the up side of the actuator, and the door opens. The limit switch blocks the signal to the wiper motor until the button is pressed. When the door is completely opened, the button is pressed and the wipers start. When the wipers are turned off, the solenoid deenergizes, and vacuum flows to the safety valve. The safety valve dumps the vacuum until the wipers are parked. Once the wipers are parked, then the safety valve allows vacuum to flow to the relay, and the relay directs vacuum to the down side of the actuator, and the door closes. One additional component for the wipers is the round **** dircetly under the steering column, between the two overrides, it's the wiper cutoff switch, it cuts power to the wipers without affecting the vacuum. It's main use it for stopping the wipers when they are extended to change out wiper blades.

Each component does a very simple task, and once the purpose of each component is understood, it all seems very simplle, and easy to understand.

*edit* Also, the wiper system does not work, and you want to see if the problem is limited to the vacuum portion, you can manually open the wiper door by removing the black plug on the wiper actuator, and use a screwdriver to push the door open. Remember the wiper door must be opened so the limit switch is activated, in order for the wiper motor to be engaged. If the vacuum portion operates but the electrical does not, and it's not the cutoff switch, the connections at the wiper motor are very easily knocked loose.

Here is a great diagram from Wilcox Corvette - http://willcoxcorvette.com/popup_image.php?pID=26609'

 

Hi mtn,
Here are the switches that mash and revi described.
Headlight door over-ride… left… pull down to open head light doors.
Wiper motor interrupt…. center…with wipers on if turned counter clockwise the arms halt where ever they are.
Wiper door over-ride…. right….. pull down to open wiper door.
Regards,
Alan

 

Thanks guys, this helps a lot. Somewhere else I posted that I wanted a C3 but wife had some issues,...in the past few days, this issue has gotten resolved and I am shopping again. (Still married by the way) Seems really strange that half of the C3's I've looked at have wipe issues. This must be something that is PM'd annually.

One of the prospects is no longer a possible. Sounded good but it's red but should be green and in my non-experience thinks it's in poor shape, states "454" but it's a NOM and I don't think it has a 454 in it now, the wipers don't work, someone punched two holes in the hood and put hood latch pins in (as if the hood would fly open going down the road), tires were shoddy, interior looked really worn and smelly, and then he says "it is a barnfind." They got "it running" after messing with the carb. The engine, whatever it is, hasn't been taken care of in a long time. Probably would be a good candidate for a rebuild but not for a first time owner.

 

One of the cars in question is advertised as a 70 454 NOM 4-speed. Was $14,999, now asking $13,999. Still, too much wrong for a first car. Someone posted to me earlier to get the most car I could afford,..this one isn't it I'm afraid.

 

Hi mtn,
Another thing to consider is how complete the car is.
This is especially important if you're interesting in a more or less stock car.
For example: buying a 68-72 that no longer has the hidden windshield wipers can be pretty expensive to bring back to hidden wipers.
It would likely need the hood, wiper bay grill, wiper bay door, door mechanism, perhaps door actuator, and varies switches and relays.
All these parts are available but could require serious $$ if you needed (and wanted) all of them.
But again… these sort of things are only a concern if you want a 68-72 that still has that feature.
So think about what the cars you're considering may be missing that you'll want to be there.
Buying parts for a car you just bought can get costly depending what's missing.
Regards,
Alan

 

Understood. For the most part the two "finalist" are almost complete. Nothing that I can see that's modified other than a few things like an air cleaner or the center hubcaps, etc. However, a lot of them do not have a right side mirror, some do and I don't know if that was an option or not,...but for me, it's a safety thing and I would add one if missing.