Helping a gentleman on a 1970 coupe....chasing down a butchered harness and wires at the pump...and relay....
i have been on Mr Wilcox site...watched the videos...and looked at the schematics....still not getting it...
On start up...wiper door opens...had a broken door vacuum relay....replaced it...chased down some butchered wires...got the wipers to start in hi...was able to go to slow...and then to park...then nothing so motor does work as should ...
In Wilcox schematic...it shows a green wire going to center of relay spade...I cut harness open and followed back to junction on cowl...only green wire is at the washer motor in the 3 plug plug...????
There is a piggyback off the yellow wire in the 3 plug plug @ motor that goes above to power the washer pump...that's all there and I understand...hot with key on...it has other piggy back that goes to the yellow on the relay....?????
So...that leads me to the title....all wires are as should be to the tach solenoid....and vacuum lines...if a tach solenoid is bad....will it cause the wiper door to open on start up and make the wipers screw up????
Oh...black white wire at switch...center...has 3 connections in the harness on engine side(appears to be org)??????

Long winded...scratching my head and the dude is looking at me like I rode the short bus to the job...hmmm....thanks in advance

 

Check the Vacuum safety "switch" in the wiper door. It should be under the passenger side wiper arm. It should keep the wiper door open if the wipers are not seated.

A Vacuum leak in the vacuum system can cause the door to open. As can a bad check valve in the feed line.

Also a leak in the headlight system can cause the momentary opening of the wiper door. Disconnect the headlights and plug the lines - see if it helps.

 

Thank you for taking the time to respond Sir...
The check valve checked out ok and the wiper arm vacuum switch is new....as the nipple on top was busted on old one....headlights are alittle slow but work with switch

 

Unplug the solenoid, if it still happens there is a leak. Most likely in the headlight system.

I had a headlight canaster seal leak and the wiper door would open and then close. I knew it was the headlight can, as the headlights got lazy or slow..

 

Your vacuum system works this way
1. The small hoses are control vacuum
2. The larger hoses are for muscle or moving that item.
3. If there is no vacuum present at engine startup. Vacuum will build up first in the smaller hoses as the volume need is smaller. So all items if in the off position should stay where they are.
4. The relays have a spring in the upper canister the vacuum overrides the springs force allowing vacuum to the item to close or stay closed. When vacuum is reduced to a set point the spring shuttle the porting to allow that item to open.
5. You have to remember Bleeding vacuum or turning on you lights or wipers causes vacuum to bleed off to allow those item to open. So any sufficient leak will cause those item to move or open. This is the fail-safe for these systems as if you lose all vacuum you can manually open the item and it will stay open.
6. A leak in the smaller hose system will allow the wiper door or headlights to move to open but once vacuum builds up in the smaller hoses everything returns to it set position.

 

Thank you for the detailed write up and taking the time to share...we ordered a new tach solenoid today...I did a test and solenoid was bad...this should fix it....hopefully....bear to get to that rascal....
Thank you all and have a great weekend...

 

Please circle back after you have replaced it and let us know if it fixed the problem.

 

On my 70 did the same thing plus I helped others so change the wiper over ride pull down cheap fix plus vacuum check your old one good luck

 

Will do and thank you....the overrides seem ok...will recheck them...know the tach solenoid didn't check out so hopefully that will fix it...