Key fob won’t unlock car anymore

[Gee-Lanty]

Why is it when you sort one issue out something else breaks apart?! :thumbsdown:

My key fob no longer unlocks my car. Lock and boot buttons work fine, when I press unlock the interior lights come on however the doors do not unlock. If I press unlock while the car is unlocked it now locks the door!

Central locking is working fine. Noticed the unlock button is a little harder to press than usual.

Just wondered if anyone has experienced anything similar?

 

[enuff_zed]

I have to say that sounds like the GM5 starting to mess about.
Do you have a second key to try?

 

[Dr. Zed]

Definitely sounds like the GM5 module, as Martin said. Has it started recently in the freak warmer weather we're having at the moment? Central locking issues in warmer weather is usually a tell-tale sign of the module going.

 

[Gee-Lanty]

No I very much doubt it’s the weather, the car has seen 40+ degree Mediterranean summers for 20 years! It’s slightly cooler now than it was a month ago.

I suspected the car battery may have been the culprit as it’s been giving me hints that it’s on its way out.

If it is the GM5 module is it something I can remove to send for repair whilst still being able to drive the car?

Sure hope so.

 

[Gee-Lanty]

Do you have a second key to try?

Unfortunately not a fob key, I do have another key but it’s just a bare key without a fob attached to it.

 

[enuff_zed]

No I very much doubt it’s the weather, the car has seen 40+ degree Mediterranean summers for 20 years! It’s slightly cooler now than it was a month ago.

I suspected the car battery may have been the culprit as it’s been giving me hints that it’s on its way out.

If it is the GM5 module is it something I can remove to send for repair whilst still being able to drive the car?

Sure hope so.

Two types. A ‘5RD’ or a ‘Star 12 Low’. They cannot replace each other.
Either can be repaired by companies in the UK.
Get it out and tell us what sort and we can advise where to send it.
Or you can get a secondhand one and code your key to it but I doubt it’ll cost much less than a repair and you don’t know how long it will last.
If you remove it you cannot lock the car and the wipers won’t work. There are other things but I can’t remember them, but you can still run the car.

 

[Dr. Zed]

You won't be able to out the roof down and the AC won't work either if I remember correctly, a really bad combination when it's warm.

 

[DashingDaryl]

Could it be that the battery in the FOB is no longer taking a charge and therefore is not sending a signal? Another FOB would be an easy way to check. You can buy one for less than $20 USD on amazon or ebay. Possibly, you could try your current fob while you sit inside the car (or as close to the module as you can get) That would also indicate a weak battery

You could also try cutting open the fob to test the battery, but I think getting a new fob would be easier.

 

[colb]

If its the board inside the key at fault, could be just one of the micro switches gone bad might be worth getting an uncut unprogrammed replacement from ebay. They can be synced to the car uncut and not prgrammed to test the locing/unlocking function as that will still work without a programmed transponder.
https://www.ebay.co.uk/itm/204297524662?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20201210111314%26meid%3Dd771f1a8908e40869cfa6629bacbe79e%26pid%3D101195%26rk%3D1%26rkt%3D12%26sd%3D204408739912%26itm%3D204297524662%26pmt%3D1%26noa%3D0%26pg%3D4429486%26algv%3DSimplAMLv11WebTrimmedV3MskuWithLambda85KnnRecallV1V2V4ItemNrtInQueryAndCassiniVisualRankerAndBertRecallWithVMEV3CPCAuto%26brand%3DUnbranded&_trksid=p4429486.c101195.m1851&amdata=cksum%3A204297524662d771f1a8908e40869cfa6629bacbe79e%7Cenc%3AAQAIAAABYObhgc4Nk8%252BdtAwOww4FKLaj%252FQ5qqgDlQCuqZA43WcPFUWDERCUugbbOk7XQv0JXlBfqCg2xKF3WcPghxGMFw2oSlXvfExEaMYr7I7LmrHcP6czY1wIMt0ORyKiCWt95xldincyyBx3g%252BNDW%252B%252FhWUgTaBhK6xAm%252BJIbCOMehu%252BdwfCQd0893iPi9rN1hDhi04hLizYg3mw1UDRGcUo1mVIyqMwPj%252FSs7vGMW6enme2RBtnMUEpslszK0fywVQ4W84rEE9ZSdAl8gFZPXUPAKu%252FwOUbHZKPNnDdaRzRuxAKZ8VpmipuLksXfUojz9jjt%252FmTbLVMs3WKQ%252B8ofJ0LS0%252FWxsBsjwR7pIjyToKgnamd66KJoIaWwzE0rfaS2tAdkTpt3kFZJK7GnivE8O%252B7opzdih8VftwyurGvYvKrBuBeJ7cEUIxnSQG5zCGLBNhX8q722VBYMu1aBu3p23Cu4Fwrk%253D%7Campid%3APL_CLK%7Cclp%3A4429486

There are also repair kits for keys that include a new battery and micro switches to put in your own key.
https://www.ebay.co.uk/itm/403937168395?fits=Car+Make%3ABMW%7CModel%3AZ4&hash=item5e0c880c0b:g:CSoAAOSwdeVjR8Ym&amdata=enc%3AAQAIAAAA4EYKg9cqhF5KSsgWcsWdoMAPL73hLZKIM37cfmLYOzHUn3SPhbQCXF2%2FIbDfuTvwa8X1KJvR1Vrmj4yX7sI3NU0W3MLZTBL9%2B8QvsZJH%2F4khkDuQQPaFFDQiwuQkLL8TPiSZIbm%2FOZjyi29SLxVrRfGxSAnZf8WbTeUR6f67C01XKEl%2FepwwB2E2CHgRB4LKgwNFGVEj%2FV8K77UeYpGoguzzv%2BsR76%2BKXWI8D9OI%2FFh7NAjLfatjJi72VFu6u3K0%2F5iDejHV6HwCNIPoueJIou7jUB%2BXF6GgAs2CTLyKhCKt%7Ctkp%3ABk9SR5Thha_jYg

With the uncut replacement you have to find a key cutter who will cut the key, some refuse to do it, if you find someone then you need to get the transponder programmed or use the one from the duff original key.

 

[enuff_zed]

[ref]colb[/ref], given that the OP is (I believe) in Cyprus (?) it could prove a right faff to try all these things.
If someone sent him an old key from another Z4, could it simply be paired to his car to test the locking function?

 

[colb]

Didn't notice he was in Cyprus, old key if the pcb and battery are still ok should sync to his car for the remote locking if the main module is fault free.

 

[Sticks]

I suspected the car battery may have been the culprit as it’s been giving me hints that it’s on its way out.

If you think it's past its best, replace it before wasting time/money on anything else.

 

[Sticks]

I forgot to say, have you tried this? https://programyourkeys.com/program-your-car-keys/bmw/bmw-z4/

 

[Gee-Lanty]

I think it’s the button on the fob itself which is broken.

I removed the circuit the other day and it worked fine, put it back together and it stopped working again.

I noticed there’s no clicking taking place when I press unlock, when I press it hard enough it activates the lock button hence my symptoms.

Thanks for the responses.