Seeking Advice from an Electronics Wizard

[Kees 594]

So I have about as much knowledge about electronics as the Americans have about building a car that can go round a corner. 

Just wondering if anyone is familiar with the classic style of BMW key found on E32s, E34s, E36s etc. 

Unfortunately the previous owners had used their nails when pressing the lock and unlock buttons, breaking through the rubber buttons. This has caused some damage to my key. 

When I press a button the little red light still flashes but I can't connect the key to my car, and when testing it with a radio, the key does not appear to transmit any IR signal as I cannot hear any interference.  

When I pulled the key apart I found that the membrane containing the button clickers is not actually attached to the circuit board. This leaves me with three conclusions:

1. The IR transmitter in the key is not receiving a signal when pushing the button on the membrane as a result of the membrane only lying on top of the circuit board and not physically being attached (but somehow the red light still flashes)

2. The second and more likely conclusion is the transmitter is toast and that is why no signal is being sent to the car. As a result of the broken buttons I wouldn't be surprised if water has got into the key and killed the transmitter as the LED light doesn't work either, as there was what seemed to be sand sitting on the membrane. 

3. The third and least likely of conclusions is that the key has been working the whole time and the last time someone paired it to the car they did so with the door open which then means the next time you pair the key to the car you have to take it to BMW (according to the owner's manual). 

 

Therefore,

Just seeking some advice as to what I could potentially do to get the key going. Could an electronics specialist solder in a new transmitter and reattach the membrane easily? Or is the key a bit of a lost cause? Would be nice to have a fully functioning key, with a working LED even. 

[Eagle 1662]

The membrane just sits loose under the rubber buttons and the board. Its not suppose to be physically attached if that's what you are meaning?

Not sure what you can do with the board myself beside clean it up and  re flow the solder joints if you believe its not working. You can get new key rubbers and membranes and probably a replacement board off an old key from wreckers. I bought some spare aftermarket fobs off aliexpress with membranes, chip, board but you can't screw them shut without buttons jamming on. Maybe others selling ones that work but these things are getting pretty old so less support.

Dealer will probably sell you one for $300-400 if all else fails

 

 

[Gaz 1060]

Have you tried pairing the key to the car?

[Kees 594]

10 minutes ago, Gaz said:

Have you tried pairing the key to the car?

Yeah, I have tried it many times to no avail unfortunately. 

[Kees 594]

17 minutes ago, Eagle said:

The membrane just sits loose under the rubber buttons and the board. Its not suppose to be physically attached if that's what you are meaning?

Not sure what you can do with the board myself beside clean it up and  re flow the solder joints if you believe its not working. You can get new key rubbers and membranes and probably a replacement board off an old key from wreckers. I bought some spare aftermarket fobs off aliexpress with membranes, chip, board but you can't screw them shut without buttons jamming on. Maybe others selling ones that work but these things are getting pretty old so less support.

Dealer will probably sell you one for $300-400 if all else fails

 

 

Yeah I have got some shells coming from AliExpress which I ordered last night so I can at least have new key rubbers. I'll get some contact cleaner and see if that makes a difference otherwise I'll get a quote from BMW although it won't be cheap. Good to know the membrane is just meant to sit on the board. Thanks so much for the words of wisdom!

[Michael. 2313]

I'd say looking at that it's been wet and been submerged. Otherside of the PCB will likely have more corrosion. 

Possibly could work being resoldered, but could be dead, damaged beyond repair. 

[NZ00Z3 187]

Arh the Infra Red remote key.  Here are some tips:

• The radio test works for the RF keys but not the IR keys.  IR keys do not transmit any RF signal for the radio to detect. To see if the IR key is transmitting, grab a digital camera, turn it on and point it at the diode as you press a button.  The IR diode will flash white if it is transmitting.
• See the attached on how to pair the key with your car.  It's a little different to the RF key pairing instructions.  It took me ages to find these instructions.  They work and fixed my problem.
• With INPA you can look in the General module or ZKE and see if the key is paired to the car and working.  There is a place where you can see a digital input (black dot) change colour when you push either button 1 or button 2.  INPA also lets you fault find further into the system if the central locking is not working.
• You have to point the IR diode at the clown nose on the inside rear view mirror for the system to work.  It needs line of sight.  Not like the RF keys which work on radio waves.

Infra-red key reprogamming instructions.pdf

Edited September 9, 2021 by NZ00Z3

[Kees 594]

11 hours ago, Michael. said:

I'd say looking at that it's been wet and been submerged. Otherside of the PCB will likely have more corrosion. 

Possibly could work being resoldered, but could be dead, damaged beyond repair. 

Yeah thought that might be the case, it's a shame when people don't look after the key seeing as its a very essential part of the car. Thanks for your help! 

[Kees 594]

3 hours ago, NZ00Z3 said:

Arh the Infra Red remote key.  Here are some tips:

• The radio test works for the RF keys but not the IR keys.  IR keys do not transmit any RF signal for the radio to detect. To see if the IR key is transmitting, grab a digital camera, turn it on and point it at the diode as you press a button.  The IR diode will flash white if it is transmitting.
• See the attached on how to pair the key with your car.  It's a little different to the RF key pairing instructions.  It took me ages to find these instructions.  They work and fixed my problem.
• With INPA you can look in the General module or ZKE and see if the key is paired to the car and working.  There is a place where you can see a digital input (black dot) change colour when you push either button 1 or button 2.  INPA also lets you fault find further into the system if the central locking is not working.
• You have to point the IR diode at the clown nose on the inside rear view mirror for the system to work.  It needs line of sight.  Not like the RF keys which work on radio waves.

Infra-red key reprogamming instructions.pdf 253.25 kB · 1 download

I had previously tried the camera trick and only saw a dull light coming out of the diode, and ended up concluding it was just reflections on the diode. However, last night I pulled the key apart again while I was bored, and I think whatever I did may have helped because I just tried it again and now I can see a clearly purple light coming from the diode. 

I will have another try pairing it to the car today as maybe its transmitting a stronger signal now? Seeing as the light is like 10x brighter than it was when I tried it before. Hoping that whoever paired it to the car last time had the door shut so it will actually work! 

When you say point it at the clown nose is that half spherical switch under the mirror that controls when Auto-Dim is on or off? I suspect maybe last time it didn't work as I was pointing the red light at it but not the diode.

Hopefully it works this time!

Thanks for your help! 

 

 

[Kees 594]

@NZ00Z3 Had another try with the key today. Tried a bunch of times and got an interesting result. Two of the times I tried, when performing the final step when pushing a button while the diode is pointed at the clown nose, the car locked itself but did not unlock which is strange, indicating the key is sending a signal, however overall the sync was un-successful. 

I think this may have to do with my central locking. Some E34s I have seen (including mine), when unlocked go [Unlock], [Lock], [Unlock] and I think that is what is probably upsetting the final part of the procedure. 

Any further ideas by any chance? 

[NZ00Z3 187]

Well that is a step in the right direction.  Well done.

Does your central locking work?  If not, then that is the next place to work.

I have not had the pleasure to work on an E34, my experience is with E36, E36/7 and E46's. So, some of the below may not apply to your car.

The E34 was made from 1987 to 1996, so the ZKE is likely to be ADS/OBD1.  If so, you'll need a scanner that can read the old ADS/OBD1 modules.  This thread may be helpful.  https://zroadster.org/threads/how-to-scan-early-model-z3s-pre-build-date-03-98.39937/

Lets break the system down to help fault finding.

• Key
• Mirror
• General Module/ZKE
• Car door switches and actuators
• Wiring

 

Keys and Mirror

You have covered most of this and got the key paired.

Use INPA to talk to the ZKE

• Confirm the pairing with INPA.  In the ZKE, there is a spot where you car see the digital input change when you press button 1 and button 2.  If this is working, then the problem is not with the Key to mirror pairing.
• Use INPA in the ZKE to "Activate" the lock and unlock signal.  This tests the ZKE Un/Lock input.  If the central locking works fine with the Activation but not with the key, then you are looking back up towards the Mirror.

 

General Module/ZKE, Door Switches and Actuators

Pull out your E34 wiring diagrams and farmilarise yourself with the inputs and outputs of the ZKE.

Use INPA to talk to the ZKE

• See if all the required inputs are present and changing when the doors/boot lock.  Door switches, actuator position, that sort of thing.  The E36 and later have a door lock actuator position signal.  Not sure about the E34?
• With INPA in the ZKE, watch the operation of the central locking to make sure that all doors/boot lock and unlock correctly.  Lots of digital signals change.  Look for the same pattern.  For example, the E46's have problems with tiny relays that drive the Un/Lock signal failing.  Just like their window relays.  You are trying to identify a relay that is failing.  These relays can be replaced if you have the soldering skills.

 

Wiring

• Check the wiring hose that goes from the boot to the boot lid.  Broken wires in this hose can cause silly central lock responses.  Very common in the E36/7 and E46's.  They call it the "Loom of Doom"
• Use the tests results from above to direct you on the signals, and activations that are not working and go searching.

[Kees 594]

@NZ00Z3 Thank you so much that is extremely helpful! Will be looking into the loom of doom today. Was doing some thinking last night and I realised by car does not double unlock itself from the central locking if the boot has been unlocked and then relocked separately. My boot wires are a bit of a mess as the previous owner just taped them to the hinge, so I wouldn't be surprised if a couple wires are pinched, causing the central locking to be a bit weird. 

I will also check all the fuses today, hopefully its relatively straight forward. If all else fails I'll dust off my old laptop and have a go with INPA. 

Once again thank you so much for your help!

P.S: my grandfather had a 2001 NZ NEW 2.2 Manual Z3 in Topas-Blau that he got with ~20,000km in 2002, would love a Z3 one day! They are great cars and look superb. 

[NZ00Z3 187]

Topas-Blau looks good on a Z3.  Manual Z3's are not that common in N.Z.  That would have been one desirable Z3.

Good luck with the repairs.

[Kees 594]

6 hours ago, NZ00Z3 said:

Topas-Blau looks good on a Z3.  Manual Z3's are not that common in N.Z.  That would have been one desirable Z3.

Good luck with the repairs.

Yeah I think the spec may have been one of a kind in NZ (it was quite bizarre). It was Topas-Blau with a matching blue interior and woodgrain. It was registered as an "2.2 Z3 M Roadster" but I don't think it had M-Package as the steering wheel was just a regular E46 wheel. And then of course it was manual and was a facelift Z3 on top of that.

I would like to buy it back if it ever came to market, seems to have done about 200,000km according to carjam. Plate was AEY825

[Eagle 1662]

On 9/9/2021 at 10:46 PM, Kees said:

Yeah I have got some shells coming from AliExpress which I ordered last night so I can at least have new key rubbers. I'll get some contact cleaner and see if that makes a difference otherwise I'll get a quote from BMW although it won't be cheap. Good to know the membrane is just meant to sit on the board. Thanks so much for the words of wisdom!

The shells probably won't work as mentioned above. I spend too much buying from different Aliexpress sellers to find that out, lots of spare key blades for my car without functional remotes.  You can swap the rubber buttons from them over to your old key though.

[Kees 594]

3 hours ago, Eagle said:

The shells probably won't work as mentioned above. I spend too much buying from different Aliexpress sellers to find that out, lots of spare key blades for my car without functional remotes.  You can swap the rubber buttons from them over to your old key though.

Yeah I don't trust stuff from AliExpress, just bought them for the rubber inserts lol. Wouldn't even trust the key blade to not snap in my ignition barrel. They were only $2 each so I bought a few because I wouldn't be surprised if at least one of them is mis-shapen at that price, and then I have spares.