Z4-forum.com

When I bought my Z4 12 months ago it came with 2 keys, both started car fine, but one wouldn't operate remote locking. I assumed dead battery and didn't really bother too much just kept it as a spare.

Last Friday, my main key, for the first time din't unlock the car remotely. Drove to work (40 mins) and later that day, locked an unlocked fine. Drove home, still fine. Saturday morning didn't work.

Suspecting battery has lost charge I googled the subject and come across someone who suggested putting key in car and switching to AUX or IGN causes it to charge. So I connected a battery charger to the car battery, put the key in, switched to AUX and locked the car up manually with my spare key (and parked wifes car in front of it on the drive for good measure). Came back to it 6 hours later hoping it would be charged. But the key is still dead!

Should this have worked? If not how can I bring it back to life (assuming it is a the key!). I don't fancy a toothbrush charger that some recommend as I have no control of the energy of the electromagnetic field and may cause harm.

Battery is probably dead. It's rechargeable but with most pre facelift e85's over a decade old (and some facelift e85 and e86 starting to cross that threshold too). New battery for both I'd say. You can cut and shut yourself but bit of a pain. There's a guy on here that does it. I'll try find his post

Bit of a read, but here it is viewtopic.php?f=2&t=99849

And this one too, think he offers standard key as well as flip viewtopic.php?f=2&t=100603

Toothbrush charger worked for me.

kis wrote: ↑Mon Nov 13, 2017 2:13 pm Battery is probably dead. It's rechargeable but with most pre facelift e85's over a decade old (and some facelift e85 and e86 starting to cross that threshold too). New battery for both I'd say. You can cut and shut yourself but bit of a pain. There's a guy on here that does it. I'll try find his post

Sorry but I disagree, its quite simple really to change the rechargeable battery. Providing you have soldering iron of course.
The battery's themselves are cheap as chips, circa £5 on ebay etc.
See this thread concurrently running in the e85/6 problem section, nice video how to in one post
viewtopic.php?f=3&t=101619

Alot seem to glue the battery in situ, I'm sure I just used a small blob of solder

Battery? Okay that's straightforward. Soldering too if you do it.

But the cutting is tedious in my opinion. Also then shutting the key again without it looking battered (you've just cut it open) is also a challenge. And I've never been able to tidy it up sufficiently for it to look acceptable...

kis wrote: ↑Mon Nov 13, 2017 7:50 pm Battery? Okay that's straightforward. Soldering too if you do it.

But the cutting is tedious in my opinion. Also then shutting the key again without it looking battered (you've just cut it open) is also a challenge. And I've never been able to tidy it up sufficiently for it to look acceptable...

I see what your saying but surely a new battery and one of the better quality replacement cases from the likes of eBay is a much cheaper option than a new key etc.

Looking at the various posts on utube, replacing the battery looks easy enough. One question though, if I replace the battery in my old key (that has never worked in the 12 months I have had the car) will the key need to be recoded to the car?

Magicarcher wrote: ↑Tue Nov 14, 2017 8:07 pm Looking at the various posts on utube, replacing the battery looks easy enough. One question though, if I replace the battery in my old key (that has never worked in the 12 months I have had the car) will the key need to be recoded to the car?

I can't say for certain but when I did one for a friend that was his spare key for his e46 it worked straight away. He said he had never used it during his ownership which was well over a year at that point.

OK UPDATE on this, I split open the key that has previously always worked, aiming to desolder the battery. Before doing so I decided to measure the voltage across the cell with a DVM. To my surprise it read 3.34V! Given it is a 3V battery I would have expected if the battery is not holding charge that it would have been less than 3V.

So I decided to hook the car up to ISTA-D to see if I can find a problem with the central locking. The only codes I get are:

000040 RLS:Optical Initialisation
00000D GM: Anti trap protection (I assume because I disconnected the battery?)
00000E GM: Anti trap protection (I assume because I disconnected the battery?)
000081 GM: Anti theft alarm memory, door contact front drivers side.
002742 DME: Misfire, cylinder 1
002892 DME: Misfiring

The first 4 all have mileage -1.

I am AT bit of a loss where to go from here!

Try re-pairing the key to the car, there’s a procedure somewhere, I’ll try and find it.

Here you go.

Z4 - Key Remote Programming

Three methods to try:

Method 1:

1. Working from within the vehicle and with the doors shut

2. Turn ignition to position 1 and back to off within 5 seconds.

3. Remove the key from ignition and press and hold the unlock button for 15 seconds during this time press the key lock button 3 times within 5 seconds.

4. Release both buttons.

5. Doors will lock and unlock to show correct programming has occurred.



Method 2:

To do this procedure you need to have one working key and one key that needs to be programmed.

1) Get in and close all doors.

2) Turn on the ignition and turn off quickly. (No more than 5 seconds) to start the process. Next action must take place within 30 seconds.

3) Remove the 1st key.

4) Hold the key up near your left shoulder (this is so it is closer to the remote receiver antenna.

5) Hold down the unlock button and press the lock button 3 times. Release the unlock button and the doors lock which confirms the operation.

6) Quickly repeat steps 4 & 5 for key #2 etc.

If it does not work, try doing the keys in opposite order. Key 2 then key 1, vs 1 then 2.



Method 3:

Alternate if you do not have a working remote

1. Turn key to position 1 five times very quickly 2. Remove key 3. Hold unlock button then press lock button 3 times, release unlock button.

4. If you have another key do the same button pressing within 30 seconds 5. Turn on ignition to finalise.

PLEASE NOTE: This programming procedure programs the remote control part of the key. Any transponder chip for the immobiliser (starting of car) will not be programmed and must be done by a specialist.

Thanks for that MJJamieson. I have one question when you say turn ignition key to position 1 is that what I normally consider the be aux position?

It's just the first notch, so one before where it sits when the engine is running.