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Showing content with the highest reputation on 12/23/2019 in all areas

  1. Ok everyone, I think I now fully understand the 1997-2011 era VAG central locking system. Same on most VAG cars as far as I know. Please tell me what I've missed! I needed to sort a lock in my mk4 golf because the rear passenger door lock had deadlocked itself. Nothing would open it. Until I had an idea. Looking at the wiring, the little DC toy motors that operate the locks connect directly to the CCU (convience box). So instead of drilling holes in the door and trying to rip off the door card destroying it, i accessed the pair of wires and simply applied 12v. First the wrong way round, locking, then the other way to unlock. Touched the wires a few times and click whir bang, the door unlocked. i could open it. Hooray! So, being a saturday afternoon and I needed to use the car sunday, i had no choice except to pull thing out to see if I could figure out what the hell was going wrong with it. No-one locally had a new lock for sale which is my usual easy and quick choice. There are 5 microswitches (front locks, with keyhole) or 3 in the rear lock mech (no key sensor). I've figured out what they all do- I think. Completely dismantled the entire mechanism and rebuilt it. The springs are a nightmare. Two switches sense if you're unlocking or locking with a key-when you turn it. On front locks only. If one of them isn't working, the central locking won't know that you're turning the key to lock or unlock. So the other doors won't lock or unlock when you turn the key. The CCU wont be aware that you're commanding a lock or unlock operation, so will just sit there and do nothing. One switch senses when the door is open. This works by cam' ing off the lock hasp- the bit of metal that hooks onto the loop you can see in the door frame. If it is defective, the interior lights wont work when you open that lock (or door), and the CCU will not know if the door is able to be deadlocked (you can't lock a door that is open). It will still try though, which is why you get some odd behaviour sometimes with lock pins popping up and down. Two more switches inside the mechanism sense if the lock is unlocked, manually lockable or deadlocked. There is a mechanical selector, that is pushed by a cheap little electric motor. When powered it can select one of the three modes. If one of these switches fail, there is no way to know for sure which state, the mechnism is in. Also causing wierd locking behaviour. Banging the door sometimes helps make the deadlocked sensor switch make contact, so you can unlock it again (or apply power directly to the motor...) If the motor fails in the deadlocked position, there is no way to unlock the mechanism without destroying the door or lock. I hope it helps someone!
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