Bruch

This weekend I hope to find the leak in my centrla locking system on a '95 90. The PO had aftermarket speakers installed in the rear doors so thats the first place I'm looking.

My question is, does anyone know the working pressure of the system? I thought I might hook up an air line at 3 psi or so to help find the leak. Pull the line off the pump in the trunk and hook up my air line there.

Any thoughts?

hubturn

While the logic makes sense that you'll hear the leak, I'd be hesitant to put pressure on something that normally has a vacuum on it, particularly something with 17 years of age on it. If you blew out a rubber bellows switch, you'd hate yourself because it would happen to be the most expensive switch in the system and it would only be available from the dealer. (Audi's Law) A note in Bentleys says that if the pump operates linger than 5 seconds, you have a leak, and that if the pump runs for longer than 30 seconds, the central locking control module must switch the pump off. I think I would start with a Mity Vac to get an idea if it is a slow leak or a big leak that might represent a disconnected line, considering that the Idiot PO was in there tinkering around. (I Hope the PO is not related to you.)

Bruch

Resolution...

Accessing the system at the rubber Y next to the pump, the Mity Vac acted like I had no hose hooked up at all. Which is how the system behaved; the trunk would lock, but the pump would time-out before the door locks moved either way. I measured the output of the pump when it was in push(blow)mode, and got approx 1-2psi. So I hooked up my little regulator that I use for pressure bleeding the brakes/clutch and put 1.5psi into the system.

I appreciate the risk, but when you have a parts car, you get brave with this sort of activity!

I heard the hissing near the pass door, pulled the panel and still couldn't find it. Turns out, there is a rubber Y under the pass side carpet that had come apart. I pushed the plastic tube back into the Y, and everything works as expected. I put a little glue on the tube for luck.

Bruch

hubturn

Excellent diagnosis in spite of bad advice. I don't know why I thought it was a vacuum system vice a pressure system. Old GM and Ford knowledge bleeding into my aged brain, I guess.

Luxus Panzer

You got any pics of the location of this "Y" junction?

The wifes 90 has a problem with both the drivers side doors not locking with the vac system

Bruch

Pull up the plastic door sill cover, after removing the front kick panel. (the panel in front of the door opening, whatever it's called)
Lift while wiggling to release it from metal spring clips.

The Y connector is under the carpet about 3 inches from the outer floor mat anchor post. You'll see vaious wires and tubes in a track under there. The Y connects the tube from under the back seat with the 2 doors on the passenger side. Be careful not to slice your arm open on theose metal clips.

BTW, the door locks open with pressure from the pump, and they lock using vaccuum from the same pump.

Tell us what you find.

Audicted

This is an awesome post.