Central Locking pump fix

[Cybersombosis]

Hi all. I sold a 2001 B5 to my brother in law and had the door lock pump replaced because it kept running until it timed out when trying to unlock. Well sure enough, he came for a visit at Easter and the new pump was running the same way all over again so we decided to investigate. We disconnected the vacuum lines to the door locks and put our fingers over the inlet/outlet and it kept running so we knew the pump was at fault, not a leak in the system.

We took the unit apart to see if the graphite rotating assembly had cracked or shattered but that was fully intact. We then took a look at what causes the pump to stop in the first place once the doors are locked/unlocked. We found there is a white cylinder looking thing on top of the circuit board that reacts to pressure and vacuum. Once there is enough pressure or vacuum resistance, the unit should turn off. This is facilitated by this white cylinder. It has a diaphragm inside that moves a block which in turn moves a metal contact back and forth. This metal contact, when it touches another metal contact, is what tells the pump that the doors are locked/unlocked based on the vacuum/pressure resistance in the line and stops the pump from running.

Please use this information at your own risk.

To stop your pump from running until it times out, cut the below tab off the unit and slide the door out of the way.



Then take a pair of needle nose pliers and bend these two contacts in towards the center metal contact. This should shorten the amount of distance the diaphragm needs to travel to turn the unit off. To test, cover the holes with your fingers to see if the pump continues to run. You can leave the little trap door off until you find the sweet spot of when the unit will work properly. I had to try 3 times before I found the right distance. If you find that after you get the unit working with just your fingers and you hook up the pump to the system and it keeps running, you most likely have a leak in your system somewhere which you will have to find and plug.



Doug

[HUFset]

Is this your final setting in the lower picture or the initial bad config?

[Cybersombosis]

This is the initial. I had the original bad unit used for the pics. The unit with the fix has left with my brother in law. If your unit works one way but not the other then you may only need to bend one of the contacts. For instance if the unlock runs all the time (pressure) then you only need to bend the contact in on the left side in the pic. And visa versa for lock (vacuum).

The contact is open towards the bottom of the picture so you want to bend with a sweeping motion from bottom left to bottom right in the pic if the unlock is running all the time.

Doug