Central vacuum locking repair on Volkswagen Jetta and Passat (mk3)

Apr 18, 2017
Central vacuum locking repair on Volkswagen Jetta and Passat (mk3)
  • Central vacuum locking repair on Volkswagen Jetta and Passat (mk3)

    Introduction

    This article shows how to repair the 3 main problem areas in the locks: the pump, electrical, or vacuum leaks.
    Mk3 90's VW and Audi cars often used vacuum to operate the door locks. Why? It appears to smoothly move the door lock plunger up and down instead of clicking it up and down like a solenoid would, like the VW MK4 cars. Unfortunately, a leak in this system can render the central locking system useless or cause one side to not function. The vacuum pump is fairly reliable, so check for other problems when troubleshooting the central locking system. Note that if the pump runs too long it can throw a code in VAG-COM - this would be your first indication that there is a problem.

    For door handle repair, see 1000q: Volkswagen door handle repair . For later years, see the FAQ linked above.

    Procedure
    There are 3 main problem areas with the vacuum operated central locking. Pump, electrical, and vacuum. There is also the possibility of a mechanical failure of the door locks but this would most likely be isolated to only one lock instead of the whole system. Here are the most likely problems.

    1. Vacuum pump broken or not activating.
    2. Door microswitch in the handle broken or wires in the door jamb coming from the lock broken.
    3. Vacuum leak in the line somewhere from the pump to the door locks.

    The vacuum pumps are fairly reliable but can be broken if the door microswitch in the handle is broken. The vacuum pump is located in the spare tire area in the passat. If the door microswitch is broken and telling the central locking system that you are constantly trying to open or close the locks, it will continuously run and break the pump. If you turn the driver's side lock and don't hear the pump running, try isolating the problem by checking the passenger side lock. If the pump activates, then the problem is in the driver's side lock.

    If the pump does not activate, then the problem could be in either the door microswitch in the handle, a problem in the wiring harness in the door jamb, or the vacuum pump. Check these as necessary.

    If the pump activates but the door locks do not work, then there is probably a vacuum leak. The driver's and pass side each share air lines, so to find a leak, lock and unlock the car and listen for the air leak.

    Try pulling back the rubber boot that holds back the electrical wires in the door jamb and wiggling out the air line to inspect and listen for cracks and leaks.

    Once you have identified a crack or leak, use 1/4 inner diameter hose to slide a patch over the line break, or use tape to patch it.