Central locking woes - FIXED!

Unfortunately I'm having some issues with the central locking and the drivers window glass which I can't solve Any help would be much apppreciated! Car is a 2003 E85 2.5 auto.

• The key fob will still remotely unlock the boot without any issues and the spare fob is the same.

• The car starts / drives fine and there are no codes related to this

• The central locking does not work either off the remote key, via the central lock button near the handbrake, or from turning the key in the drivers door.

• The drivers side window (passenger is fine) will not fully raise, (well it will for a split second but then drops again, as if you've got the door open). I think the car thinks the door is open even when it isn't. As it's a pre facelift model, it doesn't have the indicator on the dash.

• The interior lights are not coming off / on when they usually do

• I removed the GM5 Module and sent this off to repair via a guy on Ebay that comes with great feedback, as all these symptoms pointed to a busted GM5 module. Other than a 'yes definite faults on the PCB' message from the chap on Ebay, I don't know what exactly was wrong with it, but putting the 'fixed' GM5 module back hasn't fixed the central locking issue.

I'm now at a loss as to what to do next and could really do with some help.

For me it all still points to a faulty gm5… lights windows and locking

I’d borrow a good known gm5 to see if that remedies the issues?

I was thinking that. I know the Ebay repair guy has been used by many people on this forum successfully over the years, and yes the turnaround was fast, though I was a little disappointed at the lack of information / communication.

Used ones on Ebay seem to be about £80-100 quid and would obviously need reprogramming to my keys which I definitely don't have the software / skills to do.

If I plugged in another GM5 module, before doing any reprogramming, would the central locking at least work off the button by the handbrake / via the key in the door? If so then I'm wondering if someone on the forum can lend me a spare temporarily (which I'll of course send back), because if that works then I need to go back to the Ebay guy, because obviously he's not fixed mine.

A borrowed gm5 will hopefully prove the lights and window issue and the central locking will work from the central button

To link a new gm5 to the key is a simple set of button presses too so no biggie

I’m sure Barry has a few gm5s for a better price

Umfaan

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Other thing is possibly the drivers door lock? Maybe not sending signals that it is closed?

enuff_zed said:

Other thing is possibly the drivers door lock? Maybe not sending signals that it is closed?

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I think this is a definite possibility. The drivers side window not raising fully (other than for half a second or so until it drops again) would also point to this. Though this would kind of be a worse answer to the fault than swapping the GM5 for another one. I had a look on YouTube for how to change one of these and it looks an absolute PITA! :headbang:

Video here - https://www.youtube.com/watch?v=QcliSMwCGBs

The best video I found (the one above) was for the passenger side (though not a Z4, but these same door actuators are used on many BMW's) and the guy filming messed up removing the key lock barrel on another (drivers side) actuator. The comments explained how to do that correctly but I know it'd struggle if I attempted it myself. Sorry Martin, I may need your / Robs expertise on this one!

EDIT Realised earlier tonight I hadn't actually checked all the central locking fuses but of course these were fine (that would have been far too easy!)

I've just purchased a used drivers side door from Ebay for £25 - https://www.ebay.co.uk/itm/395446619673. New ones from Autodoc were a range of between £40-£80 (a Febi one, the only brand I'd heard of was £80). A BMW OEM one was £167 from Sytner

I'll reach out to Umfaan / Barry to see if he's got a cheap GM5 too so I've covered off both parts. Whichever one I don't use I'll just stick back on eBay / this forum.

Changing the door lock unit is actually pretty easy once you’ve done a few.
If you can wait until I’m back off holiday?
However, what you can do is pop the door card off, take the plug out and put it into the replacement module then lock that while holding it in your hand to see if it fixes it before faffing about bolting it in.

enuff_zed said:

Changing the door lock unit is actually pretty easy once you’ve done a few.
If you can wait until I’m back off holiday?
However, what you can do is pop the door card off, take the plug out and put it into the replacement module then lock that while holding it in your hand to see if it fixes it before faffing about bolting it in.

Click to expand...

Now that sounds a good idea and definitely something I can do! I'll know then if that's the problem or it is the gm5 still.

Better late than never (life but also the relentless cold and wet weather being in the way!) but I finally managed to fix this today.

The cause of the problem was the drivers door latch mechanism, which must have failed in the 'door open' mode because the car wouldn't let me raise the window fully. Fitted a replacement from eBay today (with some help from a friend) and it's all working again, including the window now raising fully.

Chatting to my local BMW dealership parts guy the other week, apparently BMW sold 125 drivers side door mechanisms in 2024 for the E85 (with a similar of passenger side also sold). In fact my local dealer had two of them on the shelf ready to go! He said to sell that many (and for them to have two on the shelf) for a car that stopped production now 17 years ago, suggests that the failure rate is now pretty high.

I couldn't find a YouTube video specific to the Z4 video for this job (closest was an e36), though a couple of useful things I learnt were as below;

• Unlike with an e36, you do not need to touch the window regulators to get the door mechanism out.

• The hardest bit was getting the key barrel lock out. There is an allen key behind a rubber plug on the door that you need to undo, as well as a small sliding catch (accessible from the same place) that lefts you remove the exterior door handle. This gives you much better light internally within the door. I guess the barrel lock hadn't moved in 23 years hence the stiffness!

• You want to be removing the key barrel before removing the door latch mechanism.