TheWagon

I'm hoping that someone who has gone through this can provide a technique or starting point for me. My central locking has gone out. I can lock/unlock each keyed door (driver/passenger/hatch) independantly, but unlocking that particular door has no effect on the others. I can hear the pump running - a little too long - but am thinking that the diaphram is gone. It's a relatively expensive part if I'm not certain it's bad, so I wanted to take a look at the lines first.
Point of interest: this started happening last spring ('05), and in November '04 my battery exploded. Within about 15 minutes of the explosion one night in a shopping parking lot, I doused the area in baking soda. The area was then cleaned out the next morning by a local independant. I'm thinking that the battery acid may have eaten the hose, but the time lapse between the two events makes me doubt this. I dunno. I've looked preliminarily at the hoses in the area around the battery and didn't notice any obvious hose breaches, but how are you guys seeing pinhole leaks?
I've read some threads on lock/pump issues, and all I've seen is that folks "check the lines" or "fixed a leak", but I've no idea how to begin looking through who-knows-how-many-feet of tubing buried throughout the car.

So the question: Is there a technique or tip on how to search for a vacuum leak in the hoses? Can this even be done without verifying that the pump is ok (should be easy, now that I think about it)?

The car is used primarily by the nanny, and as a family truckster on the weekend, so it hasn't been as issue that I never lock the car. But it's beginning to annoy my wife, and that means it's beginning to annoy me...

samm

I don't have an answer for you but, I don't think you will be looking for "pin holes" the hard plastic hose breaks/cracks so don't kill yourself looking for microscopic holes. I think it will be an obvious break.

TheWagon

at least I should be able to see a break or crack, in theory at least. Guess I'll just start looking to see what I see. I'll run through a forum search again, but did I see a thread on repairing or replacing the pump diaphram?

Is there agreement on the likelyhood of seeing cracks or breaks, rather than pinholes?

Rowingmurphy

Forget pinholes. Vacuum failures tend to be binary and not subtle. If the pump's working correctly, it will provide more than enough vacuum to overcome small leaks.

Anybody got a link to a vacuum diagram for C4 wagons? If I knew what the different colored lines were, it would save a lot of time diagnosing this same problem on my wife's '97 A6Q avant.

Jerry