Sweet70

I have a1970, my windshield wiper door opens when vacuum is in the system regardless of any selection. If I manually close it when the engine is off, it opens again as soon as the engine is restarted. The headlight system operates fine. I have replaced the complete vacuum hose set and the wiper door vacuum relay valve. I ran 12 volts to one terminal and grounded the other on the windshield wiper door solenoid and it appears to be operating. With the engine running there isn’t any vacuum at the solenoid outlet going in the direction of the wiper door vacuum relay valve.
Questions … Based on this explanation is my solenoid functioning correctly? What originates the electrical input signal to the solenoid to open or close it? As I am returning from some major restoration work, is there something else that could/should be adjusted? The system operated correctly before I started my restoration work … oh well !

0Willcox Corvette

The solenoid should block vacuum to open (wipers on)
and pass vacuum when closed. (wipers off)

Pull the electrical connector off the solenoid and see if it pass's vacuum. If not, you need to replace it.

The solenoid picks up ground when the wiper switch is turned on and controls the vacuum to the relay small hose side. As soon as you turn on the wiper motor switch the solenoid should block vacuum which should cause the door to raise. If the switch is working okay... then double check your hoses on your over-ride switch and the arm switch.. and don't forget to make sure the vacuum over-ride is not pulled too..

Sweet70

Wow!!! thank you for the quick and graphic response. I'll need a bit of time to digest this and do some further checking. As I'm sure you know getting to the solenoid is a pig of a thing especially since it's all back together. I thought of another detail that might help identify the problem. After loading and testing the solenoid cycling I also checked for power incoming from the electrical connector and power was there. With this added info do you think the dash mounted selector is bad? or is there a way I can test it? I'm thinking I would rather gamble on replacing this switch than going back to the solenoid.

0Willcox Corvette

The solenoid is easy to check to see if it's working.... Pull the vacuum over-ride switch from the column cover. Start the car with the wipers off and then pull the hose off closest to the **** (lower one) see if you have vacuum there. If you do, then turn on the wipers and see if it falls off. Then do the same test again on the other hose to make sure you don't have the hoses reversed.. You should be able to hear the solenoid click when you turn on the wiper switch. (You can do that just by turning on the key with the wiper in the on position).

But your problem could be anything between the solenoid and the relay... So starting with the relay and working backwards would be smarter. For the door to open, no vacuum is present on the small hose side for the relay. So double check all your hoses... then start testing working backwards. If you have replaced the arm relay recently that could be your problem, currently no one makes one that works!!!!

Sweet70

I have been looking around this afternoon and wrote this message off line before I noticed your recent reply. I have checked to see if there is vacuum at the solenoid outlet but there isn't, Please have a look at my thoughts here, I'd be grateful for your comments.

Thank you I have looked over your diagrams and have some questions. Firstly, the vacuum over ride is in the normal drive mode.

If I understand the sequence of operation correctly, it’s this.

(1) Under normal driving conditions the solenoid has no electrical input and is open allowing vacuum to pass through it to the downstream components keeping the door closed.

(2) When selecting windshield wiper operation the windshield wiper selector energizes the solenoid causing it to close, this prevents vacuum beyond this point and permits the door to open.

If my understanding is correct, my system seems locked in (2), no vacuum was detected beyond the solenoid and power was apparent at its electrical connector. With the electrical connector disconnected and power applied to the exposed terminals I could hear the solenoid cycling. Before removing the driver’s side dash again I would like to see if it is possible to determine if there is a fault in the solenoid or the windshield wiper control switch. If condition (2) is taking place because power is wrongly being directed to the solenoid by the windshield wiper switch, by removing the electric connector from the windshield wiper switch, would you then expect the solenoid to revert to (1)? Or is there a need to jumper terminals to create this scenario? If after disabling the windshield wiper switch the solenoid remains closed (2), then the solenoid is faulty. On the other hand, if the solenoid reverts to condition (1) the windshield wiper switch is likely to be faulty. I’m not an electrician but this seems logical, I would appreciate your comments, thank you.

kjbuster1

I had the same problem. The w/s wiper arm safety switch, on the right hand of the cowl and under the rh wiper arm, was broken. Changed it and all was ok.

Good Luck.

Dave J

This is true. This allows vacuum to follow the course of components to the wiper door relay, ultimately energizing the wiper door actuator to close the wiper door.

This is also true. Along with this scenario, any loss of vacuum to the wiper door relay results in the door opening.

If you do not have vacuum present in the hose coming from the solenoid, and suspect that is powered full time, check the vacuum with the ignition completely off with a vacuum pump. If you don't have one, you can borrow one from many parts stores. Turn the key slowly to power the ignition on, and listen for the solenoid engaging.

I have a suspicion that your components are still good, but somewhere along the line during re-assembly, your plumbing was gone awry. If you can verify the solenoid is clicking off and on, we can go to the next step.

Sweet70

Dave,
Thank you for taking the time to consider my problem. When I replaced all the vacuum hoses I was very careful in replacing them one at I time. If we take a step back to the vacuum system prior to the solenoid there is a T in the line, one branch goes to the light side the other goes to the solenoid input. Since the lights function correctly it's fair to assume vacuum from the same source is reaching the solenoid input.

I'll try your suggestion but need a clarification, where should I attach the vacuum pump? solenoid input, or solenoid output or on the hose going to the wiper vacuum valve? I do not own a vacuum pump so I'll need to borrow one as you suggest.

I did buy a replacement wiper relay actuator valve but before installing it did some additional testing on the old one. I removed the small vacuum hose from the top selector valve and applied bodily vacuum via suction and the door closed. This at least validated the lack of vacuum is the issue.

Yes, I believe the solenoid seems to be locked in the closed position. Since this electrically cycled I have been trying to figure out if the electrical input signal is at fault.

I would change the solenoid in a heartbeat if it didn't require removing the drivers side dash. I did remove the center dash to gain access to the electrical connections etc but I think it's impossible to get at the two retaining screws this way.

Sweet70

Thank you for the advice. When I first experienced this problem I did suspect the wiper arm relay valve so I changed it but the problem persisted. I later discovered the valve was not receiving any vacuum from the solenoid valve which seems to be where my problem originates.

Sweet70

Engine running ww switch off ... no vacuum at either hose.
Engine off, ignition on, when the ww switch is moved to on, it sounds like the solenoid is cycling.

0Willcox Corvette

Yeap.. That doesn't sound good... Well it sounds good, but it doesn't appear to be working.

Okay.. I would pull the vacuum hose off the single nipple side of the solenoid... check vacuum there. The make double sure you have the other (out) vacuum hose on the 90 degree nipple.. (like it's shown in the picture above.. if it is, then I must say you need to replace the solenoid.

Sweet70

I removed the yellow stripe hose from the end of the solenoid that has the electrical connector on it. This hose goes back to the T junction that also supplies vacuum to the light system ... I did have vacuum here.

The white stripe hose is connected to the 90 degree fitting at the other end of the solenoid. The other end of the this hose is fitted to the top location of the over ride switch.

I believe these connections to be correct. I also did some limbo positions and think it may be possible to change out the solenoid without removing the complete dash. I looked at your website and was unable to locate the solenoid in your inventory, is this the case? otherwise, my usual supplier has it.

Just for the heck of it, I thought I would just try connecting the yellow stripe hose directly to the white stripe hose which would affectively bye pass the solenoid and allow vacuum to the down stream components that I thought would keep the door closed, but instead it opened ... I think I'm going back to bed!

Dave J

If you can reach and connect to each side of the solenoid, simply connect a vacuum pump to the single port (electrical connector) side, and pull the override switch out. This would block vacuum at the override position if everything is working properly. You should be able to get the circuit pumped down in vacuum, with no leaks. If this is your result, push in the override, and you should loose all vacuum in the pump dial. You can also do this with lung power, and use a vacuum gauge on one end.

Did you get the solenoid to click when you turned the ignition on, or when you activate the wiper switch?

0Willcox Corvette

The hose from the solenoid goes on the over-ride nipple closest to the ****... or the lower one... in my picture above, the switch is upside down.

Willcox

Sweet70

[QUOTE=Dave J;1585952829]If you can reach and connect to each side of the solenoid, simply connect a vacuum pump to the single port (electrical connector) side, and pull the override switch out. This would block vacuum at the override position if everything is working properly. You should be able to get the circuit pumped down in vacuum, with no leaks. If this is your result, push in the override, and you should loose all vacuum in the pump dial. You can also do this with lung power, and use a vacuum gauge on one end.

Did you get the solenoid to click when you turned the ignition on, or when you activate the wiper switch?[/

Dave,

Engine running, vacuum at solenoid input, (yellow stripe hose attached to solenoid side that has the electrical connection.
Engine running ww switch off ... no vacuum at solenoid out side hose (white stripe hose attached to 90 fitting side of the solenoid).
Engine off, ignition on, when the ww switch is moved to on, it sounds like the solenoid is cycling.

Sweet70

Confirming the white hose from the solenoid out put is attached to the override switch as shown it your schematic at the location closest to the operating ****.

Dave J

Correct operation

Not proper operation. Should have vacuum through the solenoid.

It sounds like you have proper electrical connections to the solenoid then. Your problem then lies in the fact that vacuum is not passing through to the output side of the solenoid. The vacuum path internally could be broken, or the passages are simply blocked with crud (I've experienced it with a used one I bought off that auction site).

It appears that is your next step. I reached the solenoid under the dash of my '70, and after poking around a bit, you may be right. I managed to get a small deep 1/4" socket on one of the screws.

Here's a pic to help you orient behind the tach, hope it helps......

Sweet70

Dave,
I did some more poking around this morning and I believe you are correct about there being a blockage internally in the solenoid. When I purchased the car there was not a filter in the vacuum line as it comes off the manifold. It does now, but who knows there could be many years of crud in it. I have a vacuum gauge so I was able to run some tests. Here’s what I discovered.

Engine running, yellow solenoid input hose disconnected and attached to vacuum gauge…17”

Engine running, white solenoid output hose attached to the vacuum gauge … 4-5”

Engine running, yellow and white hoses connected to each other (taking the solenoid out of the loop). Override switch set in normal run mode, WW door went from open to close. I opened it prior to the test.

Same as above but this time the override switch was opened and the WW door opened.

I think this is the “smoking gun”, I’m sorry for originally stating there wasn’t any vacuum at the solenoid output, it was hard to detect and really needed the gauge to measure it.

Thank you for the pic, I think I’ll remove the driver’s seat to be a little more comfortable when going for those two screws.

Thank you.

Dave J

The filter coming off the manifold and upstream from the check valve will not help the solenoid. It is to protect the engine from debris sucked into the manifold through the vacuum system. I believe the solenoids when new had a small filter attached to the vent on the straight end of the 90 degree side.

Maybe when you get the solenoid removed you could try blowing compressed air through it to dislodge any debris. I would much rather stay with an original solenoid than play roulette with the Chinese stuff.

Good luck, let me know how it goes....

Sweet70

Dave,

Yes I see that ... two good points! I was just going to buy a replacement solenoid but this could save $60 or so. When I purchased the car a mouse nest blew out from the fresh air vent, so perhaps there are other boarders!