Thanks for the reply. I'm trying to narrow the failure down a bit. From what I've read, the same DAS system is used on the latter model Electronic Ignition Switch (EIS), the SKREEM and the EIS both use the same Motorola CPU chip to store the key information. BTW, the immobilizer in the EIS's also works with our Crossfire ECU (which is another solution if nothing else works). When the EIS's fail, it's usually because the file on this chip gets corrupted. It's only a small file and I've been trying to work out it's format. I have a decoder that can read these files and give me the information for the eight associated key files (so I can make the keys) but I want to try and work out where the serial number it shares with the ECU is kept. I expect it will take quite a while to understand the basics of these files.