72 wiper door solonoid test

[Robert B.]

Can anyone help with a test to see if the vacuum part of the wiper solonoid works correctly? The solonoid I am describing is located attached to the tachometer under the drivers side dash. It has three ports (one is a vent) there is also an electric connection. Is there anyway to check this with a vacuum pump? The electric part seems to work.

Also if the round windshield wiper switch (located between the two vac overide switches) is in the on position should it block the windshield wiper switch from operating?

Thanks

[Mark A.]

Re: 72 wiper door solonoid test

To test the solenoid, hook up 12 volts to the 2 terminals. Put a piece of rubber hose on one of the ports. Not the vent port. You can use a MityVac to apply vacuam to the hose. In the closed position it should hold vacuam, and when power is applied it is wide open. Mark

[Paul O.]

Re: 72 wiper door solonoid test

Robert not sure what you mean by on position of the override switch. But when a switch is on power or current is allowed thru to complete a circuit when a switch is off the circuit is open and no current flow. So if you have voltage thru the switch its on. No voltage its is off. Paul 18046

[Robert B.]

Re: 72 wiper door solonoid test

Thanks I will test

[Jack H.]

Re: 72 wiper door solonoid test

Hint: all of the in-cockpit vacuum controls work the same way. They vent vac to actuate the item they control!

So, when the solenoid is de-energized, it should pass vac from input to output and the vent will be closed. Wnen the solenoid is energized, the vent is open/active...

[Robert B.]

Re: 72 wiper door solonoid test

Good rule thanks. I suppose I cold bypass the solonoid as well from the vacuum source to the override switch to see if that fixes the vacuum leak. More tests...

[Jack H.]

Re: 72 wiper door solonoid test

Yes, that troubleshooting technique works (bypass the WSW solenoid)! Also, simply LISTENING works too...

By that I mean, station a 'donor' car outside the garage, tap into its vac system using a LONG section of hose. Route the hose into the garage, connect it to your car substituting for the manifold source and CLOSE the garage door.

Now, without your engine running to create source vac, you can simply listen, here/there to find those pesky vac leaks. That's nearly impossible when you run your car's engine to create system vac!

The vac circuit you're troubleshooting is: intake to filter, filter to check valve, check valve through the firewall into the engine compartment to WSW solenoid. Then, a series run from the WSW solenoid to the wiper door override switch, override switch back out through the firewall to the wiper door relay.

ANY component in the vac control path (vac solenoid or override switch) that vents vac, triggers the wiper door to open. Check for faulty vac switches that don't close fully, loose vac hoses and vac hoses that've deteriorated either at connecting nipples or by rubbing against something along their routing path...

[Robert B.]

Re: 72 wiper door solonoid test

Thanks great advice. I need to try the donor car trick. My solnoid works I bypassed it and connected both input and output and it held vacuum. However when I bypassed the solonoid it did not fix my vacuum leak. Back to the drawing board. Time for the donor car....

[Brian T.]

Re: 72 wiper door solonoid test

One thing that I believe was overlooked. One terminal gets 12v, the other is ground.It makes no difference which is which.

[Robert B.]

Re: 72 wiper door solonoid test

Gentlemen,

Thanks for all you help. After testing all the relays and actuators and changing the vac lines my leak turned out to be an actuator relay. I had originally discounted the relay as I had replaced it. Turns out the relay was defective and I went through the entire system after I identified my leak right out of the gate. Oh well I know how it all works now. I replaced all three actuator relays and my big block idles like a sewing machine. Thanks.

Rob