Spare key won't start car

O

oldgitdave

Senior member
 Derbyshire
Basically the starter motor won't operate using the spare key. All remote buttons work correctly & ignition lights come on but then nothing at all happens when turning the key to the engine start position.

This is what I've done:
Found the spare key battery was totally flat after buying my Zed a couple if months ago. Read up on the forum & charged it using toothbrush charger overnight & then paired both keys to the car. Tried all the remote buttons on the spare key, all working fine so I put it to one side for the last few weeks & continued using original key. So, I then thought as the keys are 13+ years old I'd buy 2 new rechargeable batteries from fleabay. Soldered a new battery into the spare key, which I found had been opened up before, & then re-paired both keys again. All went well with remote buttons all working. This time I thought I'd use the spare for a while but the engine will not turn over with this key.
Any ideas? Guess the key might just be knackered, hence why it's been opened up before?

Thanks,
Dave
 
Did it work before?

I recently purchased a BMW and the second key would not work, tried recharge, wouldn’t open the doors or anything else. Went to the dealership and questioned them, at this point I compared the two keys......the bastards at a different dealership mixed up the keys 8 years ago and gave the man I bought the car from one key that worked and two that didn’t, the ignition and the valet. He never tried the keys for all the time he had the car ! :rofl:
 
The battery in the key is not needed to start the car. The key contains an RFID transponder that is energised by the receiver coil around the ignition barrel. This causes it to communicate with the EWS module, and provided it has the right passcode, the EWS issues a random code to it, and the key responds with the correct code. All of this assumes that the key is registered in the EWS module, which has space for 10 keys.

The rechargeable batteries do fail with age, BUT they are only required for the remote lock/unlock functions. I would be initially reading the key and checking it contained the right date, it stores the EWS type, VIN, mileage and assigned key position amongst other things. Reading the key would tell me if it is corrupt (rare) second stage is to read the EWS and make sure said key data is stored in it.

The chips in the original BMW keys CANNOT be reprogrammed, regardless of what anyone tells you, the replacements I offer contain rewriteable immobiliser chips.

Where are you, I can help with all of the above.

Mike
 
jamie_z4 said:
Have you misplaced the immobiliser chip out of the key? Sounds most likely culprit
Click to expand...

Can that happen? I'd assumed it would be part of the circuit board. Here's a pic, is there anything missing?
20170927_220439.jpg
20170927_220454.jpg

mcbeee said:
Did it work before?

I recently purchased a BMW and the second key would not work, tried recharge, wouldn’t open the doors or anything else. Went to the dealership and questioned them, at this point I compared the two keys......the bastards at a different dealership mixed up the keys 8 years ago and gave the man I bought the car from one key that worked and two that didn’t, the ignition and the valet. He never tried the keys for all the time he had the car ! :rofl:
Click to expand...

Dont know.

The 'key' itself is identical to the one that works. It turns all the locks so I think that bit is correct. I only tried it in the ignition barrel yesterday when I found the problem after replacing the battery. Reluctant now to put a new battery in the original key now in case it's something I've done. It works fine so I'll leave well alone :) .
 
OEM keys don't have the "separate" immobiliser chips that the aftermarket one's do, as it's built into the circuitry on the board. The "antenna" for it is under that sticker, the other "coil" is the inductive charger for the battery.

Mike
 
Ducklakeview said:
The battery in the key is not needed to start the car. The key contains an RFID transponder that is energised by the receiver coil around the ignition barrel. This causes it to communicate with the EWS module, and provided it has the right passcode, the EWS issues a random code to it, and the key responds with the correct code. All of this assumes that the key is registered in the EWS module, which has space for 10 keys.

The rechargeable batteries do fail with age, BUT they are only required for the remote lock/unlock functions. I would be initially reading the key and checking it contained the right date, it stores the EWS type, VIN, mileage and assigned key position amongst other things. Reading the key would tell me if it is corrupt (rare) second stage is to read the EWS and make sure said key data is stored in it.

The chips in the original BMW keys CANNOT be reprogrammed, regardless of what anyone tells you, the replacements I offer contain rewriteable immobiliser chips.

Where are you, I can help with all of the above.

Mike
Click to expand...

Hi Mike,

You did my roof motor a few weeks ago. Pig of a job if you recall as someone had stapled the plastic casing bracket together which could have punctured the hydraulic lines.
I'm in Derby so it's a bit of a run for me to your place, especially the state the M6 is in at the moment. Reckon I might need to pop up sometime soon though, can't really be relying on just one key! Thanks for the info. I'll be in touch when I have some spare time.

Dave
 
oldgitdave said:
Ducklakeview said:
The battery in the key is not needed to start the car. The key contains an RFID transponder that is energised by the receiver coil around the ignition barrel. This causes it to communicate with the EWS module, and provided it has the right passcode, the EWS issues a random code to it, and the key responds with the correct code. All of this assumes that the key is registered in the EWS module, which has space for 10 keys.

The rechargeable batteries do fail with age, BUT they are only required for the remote lock/unlock functions. I would be initially reading the key and checking it contained the right date, it stores the EWS type, VIN, mileage and assigned key position amongst other things. Reading the key would tell me if it is corrupt (rare) second stage is to read the EWS and make sure said key data is stored in it.

The chips in the original BMW keys CANNOT be reprogrammed, regardless of what anyone tells you, the replacements I offer contain rewriteable immobiliser chips.

Where are you, I can help with all of the above.

Mike
Click to expand...

Hi Mike,

You did my roof motor a few weeks ago. Pig of a job if you recall as someone had stapled the plastic casing bracket together which could have punctured the hydraulic lines.
I'm in Derby so it's a bit of a run for me to your place, especially the state the M6 is in at the moment. Reckon I might need to pop up sometime soon though, can't really be relying on just one key! Thanks for the info. I'll be in touch when I have some spare time.

Dave
Click to expand...

Oh yes, I remember THAT one lol.

No probs Dave, you have my number.

Mike
 
Ducklakeview
Hi Would you be the chap advertising on ebay for roof motor repairs?. If so you have just received my motor.
 
Mike6 said:
Ducklakeview
Hi Would you be the chap advertising on ebay for roof motor repairs?. If so you have just received my motor.
Click to expand...

I am Mike, and yes it's arrived. Will get onto it tomorrow.

Mike
 
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