I need a wiper/door expert for a 68. The vacuum is all routed correctly, and the door will open and close with the override switch.

But here is my main problem. As soon as I hook up the battery to the car, the solenoid behind the tach is energized. (I believe this is what was causing my dead batteries). When the car is started, the wiper door opens (as it should when the solenoid is energized) even when the wiper swtich is off. If I disconnect the power lead to the solenoid, the door closes (as it should when there is no power to the solenoid).

Why do I have constant power to the solenoid? Shouldn't this be switched on/off from the wiper switch?

I have been reading all the other posts about this, but I did not find any solutions. I have read that there is a "park" switch by the right wiper arm that should cut power to the solenoid once the wipers are fully seated, but I did not see one. Maybe I looked right at it and didnt know it. Can anyone help with the location of said switch?

Also, does the "park" mechanism in the wiper motor have anything to do with the energizing/de-energizing of the solenoid?


It sounds like it would be a simple fix, but I'm getting too irritated to think straight.

All help is greatly appreciated.

~Rich

 

Not sure about the solenoid power, but the switch is actuated by a plunger that's bolted (length is adjustable) to the wiper door via a linkage. The plunger sticks out of a hole in the firewall. The switch and plunger are mounted on the firewall about 12" from the passenger side of the drip ledge, in between the wiper motor and wiper door actuator. The switch is just a little black button.

 

Here's the best picture I've got...

 

Thanks for the reply, but I think that switch is the limiter switch which tells the wiper motor that the door is completely open and it is OK to run the wipers. All it does is complete the circuit for the motor.

I need to know what switches the brown wire on the solenoid to +12V, then cuts that power when the wipers are parked.

~Rich

 

Here's how these are *supposed* to work (assumes you have the original door mechanism).

I think you are on the right track. The power to the solenoid should only be on when the wiper switch is in "low" or "hi" positions. If you are sure power is off when the switch is off, then you might check the position of the interlock valve under the passenger side wiper arm (second photo - under the wiper door). This switch tells the system that the wipers are parked and it's OK to close the wiper door. If this switch thinks the wipers aren't parked, it will cause the wiper door to remain open, or in your case, to open once there is vacuum after the engine starts. Maybe the wipers need adjustment in this area.

Lastly, make sure the valve under the steering wheel (over-ride valve) is in the up position).

Good luck -

 

The override switch is definately closed.

How can I verify that the wiper switch (on the dash) is not faulty? I don't beleive that is is, considering the wipers only run when the switch is turned to lo or hi.

I'm at work now, but I will check for the interlock as soon as I get home.

Is this interlock switch electrical in any way? I didnt see any connections on the diagram above, only vacuum.

Thanks for the pics....Huge help.

~Rich

 

I always thought the "park" switch was in the motor.

I really think you are on the right track with this, but I'd suggest getting a new wiper motor. Why? You are drawing current and nothing is happening. This is bad and means that a motor is burned up somewhere (I think the park motor).

Also, a new wiper motor is only $55 at AutoZone ( + $10 core) and will save you time in the long run.

If memory serves, the switches in the dash just send 1 (or more) grounds to the motor.

 

My 68 doesn't have the park switch (interlock valve on the drawing, circled yellow in pic) you guys are talking about, I am pretty sure it is a "69 on" addition because the wiper door was closing on unparked arms. It is a vacuum switch, not electrical.
It's job was to make sure the wiper door did not close until the wiper arms were fully parked by the motor.
The other switch (circled red in pic) which is activated by the wiper door is to make sure the door is fully open before the wipers start.

Can you pull the electrical connector off the solenoid and check for volts and earth? The 12V is a continuous supply not controlled by the ignition switch. If you are getting an earth from the switch with the switch off, pull the panel with the wiper switch (three screws and maybe the gauge defogger, no a/c) and disconnect it to see if you still get the earth at the solenoid. This is either a wiring problem or damaged insulation. If the earth disappears when you disconnect the switch then it appears you have a faulty switch.
Hope this helps

 

I had the same problem on my 68. The wiper motor gear box relay is in the wiper motor. If this relay is closed, power will be supplied to the vacuum control solenoid. This is how it is supposed to work:

Wiper Off- The wiper motor gearbox mechanism is programmed so that when the blades reach the park position, the gear mechanism opens the gearbox relay switch contacts. This shuts off the wiper motor and opens B+ circuit to the vacuum control solenoid, which allows the lid to close.

Try this link www.corvettefaq.com/c3/1968Wiper.doc

Scroll down to page 5 and there is a wiring diagram of the 68 wiper motor. Look at terminal 8 (red wire) and terminal 7 (Brown wire). The red wire is a direct connection from the battery to the wiper motor gear box relay. With that relay being closed, every time you hook the battery up, you hear that clicking sound of the vacuum solenoid being energized. If your wiper motor is in the park position it should open this relay.

I did not have any luck taking the wiper motor apart to see if I could repair it myself. I bought a 68 wiper motor from Autozone. Problem solved!
Bryan

 

I thought you had already checked out the electric portion. RHD '68 L89 is probably right about the '69 up regarding the interlock (it's vacuum only). My manual is for 69-70 Vettes and most of the time the info pertains to '68 also. Here's the scematic for the wipers. I can't imagine it changed that much in a year.

edit: OK - it IS somewhat different than the 68 from the post above...

 

RHD is correct. There is no interlock on the 68. (damn one year only stuff).

I'll follow the above tests and post results when I have a solution.

Thanks for the support.

~Rich

 

I believe you either have a bad wiper switch (that's what sends power to the relay on the back of the tach) OR you have the plug to the wiper switch plugged in UPSIDE DOWN - it will fit that way and if I remember correctly, will act as you have described if wrong.

 

Well, I spent a bit of time on it last night. The plug on the back of the switch will only fit one way. The switch checks out as being OK.

I pulled the motor apart and found the red (constant power) wire going to the park relay was soldered to the same terminal as the green wire. The green wire is the one that connects to the brown for the solenoid. This makes no sense to me whatsoever.

I left the washer motor off, and hooked the wiper motor back up. When the wipers parked, a spark jumped from the relay to the motor housing. I am pretty sure this was not part of GMs design. I ordered a new motor from AutoZone, and I'll have it tomorrow.



~Rich

 

Hope the new wiper motor solves the problem. These 68's do have a unique wiper system. Keep us posted.
Bryan

 

Today was the first day I had a bit of spare time to spend on the car.

And the results.................GOOD NEWS!!

Problem solved. It ended up being a faulty park switch/wiper motor.

This solved my dead battery and "wiper door always up" issues.

Now, I have a new problem. The washer pump is not spinning. It just bangs away in front of the wiper motor. I know there are other threads on this, so its time to start reading again.

Thanks to all those that contributed.

Oh yeah...I got the motor at AutoZone like BeaterShark suggested.


~Rich

 

The wipers have to Park to close the door. The power that pulls in the realy is a direct power it comes from the starter. Through the plug behind the wiper motor. This power will also park the wipers and close the door when you shut off the wipers. Now here is what worked for me. Take a 12 Volt test light and hook it up to ground in the engine bay. The switch on the firewall that tells you that the wiper door is open has a plug on it. Open that up and test for power with your test light. One side should light and the other won't. This is your path to ground for the wiper motor. If the switch is bad it will not allow the motor to run. If you now take a jumper and ground that connection the wiper will run and park. The power to the relay under the dash will go out and your battery should stay up. The other wire coming out of that switch on the fire wall goes back into the harness in to the car and connects through the vacuum over ride switch. I really don't know why but it does. That is where I found my problem from there it goes to ground with every thing else under the dash.

This thing drove me nuts for two weeks. I bought another motor then I got an assembly manual and finally a repair manual through Helms. The Helms manual is great if you want to take the wiper motor all apart.

I hope this helps