Re-synchronising central locking?

G

Gogo

Member
 Yorkshire
I recently purchased my 2004 Zed from a (non-BMW) dealer. It has gone back in for some warranty work including some issues with the remote central locking. Everything locks OK but the doors dont unlock - the passenger door is deadlocked and the drivers door will open with the key but the alarm doesn't go off. The central console is also locked. The boot locking/unlocking works fine. From reading the forum this looks to me like the "classic" GM5 relays problem.

The dealer sent it to a local auto electrician who has apparently "re-synchronised the central locking" and claims it is all working fine. I haven't managed to find any reference to this process on the forum which makes me a little wary.

Does anyone have any thoughts on this?
 
It's a legitimate procedure. You could have done this yourself. It's some particular sequence of ignition switch position and lock button pressing for each key in turn. It synchs the rolling code security handshake routine. I'm surprised you didn't find anything on this, it's a common troubleshooting step with locking issues.

The relay issue is often intermittent so it's possible it was behaving for the electrician at the time. (How do intermittent problems always behave when it's the mechanic observing?) Don't be too surprised if the problem crops up again.
 
Thanks for the response - I had missed that procedure!

You are right - the problem is intermittent, although the dealer has seen the problem. I was wondering if it had started working again and they were just trying to pull the wool over my eyes - at least there is some validity to their claims!

I'll just have to make sure that the fix is subject to a testing period.
 
Definitely do all you can to induce an error. The rolling code synch that is reset by what they did is digital in nature and not prone to intermittent errors. It typically either works or it doesn't. I will allow that there is a chance this fixed it and you will not have problems, but I'm sceptical. If you're paying for this, stay away from the dealer, they will first try to reflash the GM5, which will not work, then they will charge you to replace the entire module, quite dear. You can have the relays replaced for much less through an independent service.
 
Thanks again bcworkz - you advice is very welcome! Your further comments just reinforce my own views. Personally I think it is the intermittent nature of the fault. In the event that I can't get it to error again within a reasonable time I already have "Plan B" in place as I have spoken with the guy that can replace the relays at a reasonable price.
 
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