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  #1  
Old 05-27-2008, 01:31 PM
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Mike
 
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Master Vaccum Switch/Door locks

I'm trying to diagnose my door lock vacuum problems. New check valve in engine compartment. The lines and actuators all work and hold vacuum (when tested after the master switch in the door). However, the master switch itself seems to be leaking.

Can someone verify proper operation of this valve? It seems that on locking, it holds vacuum, and unlocking it dumps all the vacuum (or the other way around). I can hear a *swish* as the vacuum is released. Is this correct? It seems it only holds vacuum when the pin is absolutely seated in the switch. It might also be the check valve that is in-line on the vacuum line to the switch itself? I have tested that valve and it seems to leak when i plug it with a golf tee, though not when i put my thumb over it...Argggh....

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Old 05-27-2008, 04:56 PM
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When you hear the *swish* its probably the vacuum rushing from the reserve tank into the unlock (or lock, whichever state you're moving to) circuit. But if there was a leak at the main switch, you'd probably hear a constant hiss that gradually falls off as your vacuum reserve depletes.

The master valve in the driver's door should hold vacuum for which ever position its in, so if the knob is down, the port leading to the 'lock' circuit should hold vacuum (with the common port plugged) and vice versa. If the check valve is leaking, you'd lose all your vacuum once the engine is shut off, even if you never move the master switch.

If you lose vacuum when you unlock, it may be one of the rubber boots on one of the door elements...I had a couple that had disintegrated. But you said you just replaced all your actuators...maybe test them individually at the vac lines under the floor mats?
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  #3  
Old 05-27-2008, 06:06 PM
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Mike
 
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Hey thanks...just to clarify. I did all my testing with a MityVac at the door. So i know all the lines/actuators work because i can make them go/stay up or down this way. However, when i test the switch itself, it hisses off vacuum as soon as the pin is pulled out (door unlocked i think). It makes sense to me it should be a closed vacuum circuit--ie, that vacuum is just routed to the lock/unlock lines with no loss. Must be the switch!
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  #4  
Old 05-27-2008, 06:42 PM
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Yup, its just a 3-way valve, one common port in the middle and two "selected" ports. When the knob is up, the common port is connected to one port, when the knob is down, the common port is connected to the other.

I actually bought one when I thought mine was bad, and mine turned out to be good, and the one I bought was the wrong one for my car anyway. I don't remember if its the black one or the white one (its probably the white one since that ones a good bit cheaper and I didnt know any better at the time), but if its the one you need, you can have it for the cost of shipping. I'll post an update when I find it.
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  #5  
Old 05-27-2008, 08:21 PM
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Mike
 
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Hey! Awesome...let me know, thanks a bunch!
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  #6  
Old 05-27-2008, 08:49 PM
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Quote:
Originally Posted by mgcanuck View Post
It makes sense to me it should be a closed vacuum circuit--ie, that vacuum is just routed to the lock/unlock lines with no loss.
No, it's not a closed system. Each actuation reduces the vacuum level in the reservoir. If the lock circuit is under vacuum, the unlock circuit is vented to the atmosphere, and vice versa. In reality, the work is being done by atmospheric pressure, not vacuum.
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  #7  
Old 05-28-2008, 03:06 AM
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Mike
 
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so where is the loss in my system then? If vacuum is required to raise the door buttons, then venting to atmosphere as you say should make them go back down, no? Not happening.....and this is all with hand-pump vacuum.
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  #8  
Old 05-28-2008, 10:04 AM
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Quote:
Originally Posted by mgcanuck View Post
If vacuum is required to raise the door buttons, then venting to atmosphere as you say should make them go back down, no?
No. The door lock actuators are not spring loaded to one or the other position. They require vacuum to move in both directions. The switch basically connects the vacuum reservoir to either the lock or unlock side of the actuator. And vents the opposide side.

If you think it, I suspect that it will become very obvious that spring-loaded actuators would be a very poor choice in a door lock system.

Last edited by tangofox007; 05-28-2008 at 10:14 AM.
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  #9  
Old 05-28-2008, 10:57 AM
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Ahh..I misread your post, the system is not lossless, you do lose a little vacuum in the reservoir every time you actuate the locks, as tangofox is describing.

So when you push the knob down on the drivers door, it sends the vacuum to the 'lock' side of the diaphragms in all the other doors, meanwhile the vacuum on the 'unlock' side of the diaphragms has to be "replaced" with air, so air is allowed in through the master valve from the atmosphere. Its a little confusing trying to describe the movement of the absence of air.

The manual says you can operate the locks about 10 times after the engine is shut off (if I remember that right...I'll have to double check).

Also, the valve I have is the black one. Mine needed the white one with the holes for the screws. Check your valve with the mityvac, if its bad and you need the one I have, let me know.
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  #10  
Old 05-28-2008, 12:25 PM
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Mike
 
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Hi, thanks--i think i have the idea. When the pin is pulled out of the switch, all the vacuum drops and won't build up again. It just sucks 100% air in. So, to me that means the switch is hooped.

Pizzachef: i have the black one, so if you could send it that would be awesome.

I'll send you my shipping address in a PM.

I'll shoot you Paypal for the shipping...Thanks!
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  #11  
Old 05-28-2008, 01:21 PM
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The master switch in the drivers side door will release vacuum by design, the amount determines how many times you will be able to lock and unlock before recharging the system. I have gotten the system working in my 2 cars on 3 seperate occasions by doing nothing more than testing the system for leaks and detaching and re-attaching the three and 4-way connector along the driver and pass. side front floor. On one car I had to disconnect and plug the fuel door pod because it was leaking, and most recently had to disconnect the rear pass. side door to make the system functional. I've sealed the inlet of the vac. reservoir on both cars with silicone with good results.
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  #12  
Old 06-07-2008, 12:59 PM
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Mike
 
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fixed...sort of

Hey PizzaChef! I got the switch, thanks so much...I installed it and put my gauge on the 4-way connector to the check valve in the engine compartment. I get about 10" vacuum there, only slightly higher with the check valve disconnected and checking supply to it.

I can manually lock/unlock all doors/flap with just over 5"....I wonder what's going on?? The car still shifts fine and shuts off. I also have a leaky 3/2 valve, however it's working enough to operate as described.

arrgghh....
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Last edited by mgcanuck; 06-07-2008 at 02:46 PM.
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  #13  
Old 06-08-2008, 12:35 PM
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Hey thanks, glad its working for you. I missed what's going on though...the door locks don't operate when you lock/unlock the driver door or they do, but you can manually over-ride them with 5" vacuum?
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  #14  
Old 06-08-2008, 01:30 PM
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Mike
 
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Yes, that's it. I can make all the doors lock/unlock with a MityVac, and they hold. But with the car running, they don't work by turning the driver door key. Also, the car does not shift...there is only about 10" of vacuum at the check valve in the engine to the door locks/resevoir. I must still have a leak somewhere, but i've tested everything, including the resevoir fitting and it holds vacuum at the resevoir.

I'm thinking that since my 3/2 valve is not working correctly that the addition of the door locks on the vacuum system is just enough to keep the car from shifting. At this point all i can do is replace that valve and see if the overall vacuum increases to the door lock system.

The only other thing i didn't re-test is the check valve in the driver's door...I suppose that's easy enough to do by putting the Mityvac on the line from the engine side...
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  #15  
Old 06-08-2008, 02:44 PM
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Even with a small leak, you should be able to lock and unlock with the engine running unless your vacuum pump is weak. With the engine running, how much vacuum do you have at the large T off the brake booster line? Put a guage on that main line and if necessary, plug all of the other T connections. Mine will draw about 23" of vacuum.

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