Faulty GM5 module or key?

G

Gollom122

Member
I’ve had the car a few weeks and it only came with one key.
I’ve had a few issues including low main battery which I had to recharge. Seems to go for about ten days not driven before getting to 11v but I’ve kept the car moving to avoid another dead battery.
I don’t know if related but the key fob has now stopped locking and unlocking. Also no alarm beep when activating. However the key works the central locking and the centre console button also works. I’ve checked fuses 11,30 both ok I’ve had the key on the tooth brush charger and tried pairing the key to the car again but it doesn’t work the locks.
I’ve ordered a replacement fob battery but was considering if this could relate to the GM5 module or do the button and manual central locking functionality rule that out?
 
If its an original sealed key it may well be the internal rechargable battery is going duff. If the central locking buttons stop working it may well be down to a bad battery. If leaving it on a toothbrush charger makes no difference it may support the bad battery diagnosis. Having said that have you tried relearning the fob with the finger dance to reset it as it may have lost its settings if the battery is suspect.
Mobile locksmith will charge circa £130 for a new cut and programmed key, you will only get a manual key from BMW these days for circa £60 but it will be coded to your car to enable it to start. The battery inside the key is only used for the central locking, the transponder in the fob is not powered, just needs to be inside the fob.
To programme the central locking buttons follw this guide, if you had more than one key all keys must be prtogrammed one after the other to get them all working the same.
Programming Additional BMW Key Fobs

So if you have a working key fob, but wish to program additional keys, follow these steps:

Take the working key fob along with the ones you want to program inside the car with all doors and windows closed.

Put the working key into the ignition and turn to position 1. At this point, the dash lights and accessories should turn on.

Turn the key back and remove.


On the working key, hold down the unlock button and press the lock button (the BMW logo) 3 times, then release the unlock button. The doors will then automatically lock and unlock.


Take the new key and hold down the unlock button while pressing the BMW logo 3 times, then release the unlock button. Again the doors should lock and unlock, and you’re done.

Programming a New Key from Scratch

These instructions are for programming a new key when you do not have a working key fob.

Insert the key into the ignition and turn it to position 1 and back rapidly 5 times.

Remove the key

Hold the unlock button and press the BMW logo 3 times, then release the unlock button.

If you have additional keys you’d like to program at this time, repeat step 3 within 30 seconds from the original key programming.

Turn on the ignition to complete the process.
 
Yeah done the pairing dance and the key doesn’t initialise.
I’ve also read that the rf receiver antenna is inside the rear view mirror. Could this be a contender for my problem?
 
Could be, they do reccomend the key is held up at ear height when programming it so the receiver in the mirror gets a strong signal.
Consider buying a new blank off ebay, you could try programming the uncut key to the central locking to see if it comes to life. It obviously wouldn't start the car until the blade is cut and the transponder is coded to the car. Since you only have one key I don't suppose you fancy posting it to one of the locksmiths who offer a cutting and coding service and refurbishment of old keys by mail?
 
So I’ve cut open the key and replaced the battery. The old battery measures 3.4v and the new one 4v so I was hopeful.
Changed it over and no joy. Tried to pair the key as per the instructions above but still nothing. Held it real close to the mirror and it ain’t working.
Any idea where to look next.
Central locking working fine on the door lock and the centre console button.
 
Thanks
I’ll take a look there next.

I think I developed the fault while giving the roof a good clean and many rinses.
Does anyone know if there’s electronics that could have been effected by water.
 
Seriously tho - much of the electronics are shared with the E46 platform - so its well worthwhile checking those (extensive)
forums
 
Thanks I think I’ll need to.
I removed the mirror and opened up the glass part to find the receiver. All looked well but I gave all the contacts a good clean but it made no difference.
 
At the outset you mentioned a poorly battery showing 11v which is way too low for reliable functioning of many systems on these cars, so get a new battery and check your alternator is charging before chasing other possible answers.

You also mention the fault starting after roof washing, it's possible for water to have got in to modules under the dash, the door pillars or behind/between the seats, but sort the battery before stripping trim to check harness connections for damp or corrosion!

If the GM5 is faulty doors can still open fine with the key and internal button, BUT the GM5 needs a good stable voltage, so yet again make sure the battery is good.
GM5 https://z4-forum.com/forum/viewtopic.php?t=102586

Good luck and let us know how it goes.



............... did I mention making sure your battery is good :lol:
 
Black Friday deals on at Tanya batteries for a Bosch S4 008 £75 delivered. I know the battery is tired and have just been putting this off but from what you say it could be the cause of this issue.
No point in putting it off any longer.
 
Gollom122 said:
Black Friday deals on at Tanya batteries for a Bosch S4 008 £75 delivered. I know the battery is tired and have just been putting this off but from what you say it could be the cause of this issue.
No point in putting it off any longer.
Click to expand...

It may or may not be the problem but it's pointless looking at anything else unless you know you have stable voltage. I'm guessing that with the things you have tried you might have to re-sync everything, then if you end up where you started I'd then suspect GM5. Good luck :thumbsup:
 
colb said:
These instructions are for programming a new key when you do not have a working key fob.

Insert the key into the ignition and turn it to position 1 and back rapidly 5 times.

Remove the key

Hold the unlock button and press the BMW logo 3 times, then release the unlock button.
Click to expand...
In the E46 there's another procedure depending on your car - step 1: turn ignition to position one and then off within 5 seconds instead of rapidly 5 times (this worked in my E46 - the 5 times didn't)

Dunno if that also applies to the Zed
 
I think I tried every combination.
Central locking locked and unlocked. 1 turn, 5 turns, 8 turns on/off same result.

Does anyone know what would happen if your boot or bonnet wasn’t closed when doing this procedure? Perhaps the car thinks it’s not locked?
Anyone know if my e90 3’r keys use the same frequency? I could try pairing my Z key to that or the e90 key to the Z.
 
Think you need all doors closed bonnet down and locked boot closed before you try syncing the fobs, if one method dosn't work try the next and the last one. Hold the fob at ear height in the centre of the car near the rear view mirror when you perform the finger dqance with the buttons. Sync the first key, if it takes the doors will lock on their own to signal its programmed. All other keys you have must be synced straight after the first one, one by one till all keys are synced.
 
Here are the options for key reprogramming https://www.programyourkeys.com/BMW_Z4_Key_Remote_Control_Fob_Programming.html That worked on mine for a while, sometimes just the driver's door, but kept needing redoing.

Then I replaced my main battery which improved it for a while but I still needed to have the G5M refurbished eventually.
 
Does anyone on here know a G5M specialist repair. I am leaning that way. The only thing holding me back is the fact I only have one key so I might buy a £20 rf signal detector to see if the key is actually transmitting anything. See this on eBay.
https://www.ebay.co.uk/itm/Xhorse-Remote-Tester-Radio-Frequency-RF-Infrared-IR-300Mhz-320hz-434Mhz-UK-/275032094278?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l6249&mkrid=710-127635-2958-0
 
This is the one I've seen referred to most often and, iirc, offers a lifetime guarantee. Not used by the indy I had to do it though.
https://www.ecutesting.com/
Don't forget to add cost of secure postage.
 
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