Is the immobilizer the heart of my problem?

[Mustillo]

Hi guys,


So I've had this 1996 VW Mk3 Golf VR6 for a few weeks now. I recently drove it to Tafe on a Monday, it drove fine getting there, it also drove fine on our morning break but started misfiring on lunch break/not firing on all cylinders.


I managed to get back into the car park and park it while it was running on a couple of cylinders where I performed some basic diagnostics and the cause of the problem was a cracked coilpack which has now been replaced.


After I plugged back in the ignition leads, the car would not start at all (cutting off after 1 second). Plugging in Vagcom I receive the following error:


2 Faults Found:
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-00 -
01249 - Fuel Injector for Cylinder 1 (N30)
31-10 - Open or Short to Ground - Intermittent
Readiness: N/A


Ignore the second fault as we had unplugged an injector and that is most likely why that error is there. Obviously this is a immobilizer fault? But how does this suddenly just happen?


I am aware that there are 4 components to starting the car:


1. Key
2. Key reader
3. Key Barrel
4. Immobilizer box


I've read that the key could be faulty or, the key reader, or rarely the immobilizer box it's self. So I purchased those 4 things from a scrapyard, fitted them today, cleared the previous faults, cleaned and tested the earth to the immobilizer box but the car would still get cut off from the immobilizer.


Now I did another scan with Vagcom and pulled the following faults:


2 Faults Found:
00668 - Supply Voltage Terminal 30
07-10 - Signal too Low - Intermittent
17978 - Engine Start Blocked by Immobilizer
P1570 - 35-00 -
Readiness: N/A


-------------------------------------------------------------------------------
Address 25: Immobilizer Labels: 1H0-953-257.lbl
Part No: 1H0 953 257 B
Component: IMMO VWZ3Z0V7369602 V00
Coding: 09600
Shop #: WSC 01115
VCID: 2A5099A0D65D156E0F-4B00


1 Fault Found:
01177 - Engine Control Unit
65-10 - Unauthorized - Intermittent


Yes for some reason I have gotten more information from the scan with a new immobilizer, key, key reader etc.


Maybe my old immobilizer was fine but the key or reader was faulty? What is the cause of this cutout?


There is a possibility that the scrapyard gave me back my OLD immobilizer which I gave as an example... So they will be around on Monday to give me that one back as well. So I could have the OLD immobilizer installed at the moment hence why I am getting the exact same fault.


Anyway this is just my weeks research, wondering if any of you guys now of a bypass as well?


Thanks,


Josh

[AALocksmiths]

It could be the key but unlikely as the transponder chips rarely fail. It could be the key reader which you can kinda check with a test light, you an make sure that it is getting power but this won't rule it out 100%. They are not coded to the car so you can swap it over to test.

I have had then with faulty immobiliser boxes but again it's rare. It is possible to clone your Immo box and write the data to another if needed.

From the fault codes it looks like there is no Immo fault in the Immo box, if so it is reading the key and is happy with it. The fault may be the wiring between the Immo box and ecu.

It is possible to deactivate the Immo in the ecu but this should be a last resort.

[Mustillo]

It could be the key but unlikely as the transponder chips rarely fail. It could be the key reader which you can kinda check with a test light, you an make sure that it is getting power but this won't rule it out 100%. They are not coded to the car so you can swap it over to test.

I have had then with faulty immobiliser boxes but again it's rare. It is possible to clone your Immo box and write the data to another if needed.

From the fault codes it looks like there is no Immo fault in the Immo box, if so it is reading the key and is happy with it. The fault may be the wiring between the Immo box and ecu.

Cheers, I'll back into the workshop over the weekend, where I'll try and wrap my head around a few things. I'll have a look and follow the wiring from the box to the ECU, I could have been handed back the old immobilizer from the yard but I'll see

[Mustillo]

UPDATE: Fixed now. Swapped the new immobilizer, key reader and key, paired it with VCDS car starts fine now. I'm on the hunt for a bypass in case this happens again.

[AALocksmiths]

Depending on the ECU it can normally be switched off there. Not that straight forward though.

[Mustillo]

Depending on the ECU it can normally be switched off there. Not that straight forward though.

Yes with hours of research the internet doesn't seem likely to have an answer either, it isn't something dealers want well known on the net, but maybe no bypass is simple enough

[AALocksmiths]

To disable the Immo you will need specialist tools and it's not something that the dealer can do, part of the ECU needs to be flashed to do it.