[ian332isport]

Hi,


I'm helping some fellow MX5 owners fix or bypass faulty or intermittent immobiliser boxes. I'm initially looking at the Mk2 MX5 with Lucas 19AS immobiliser boxes. I've read the 93c56 EEPROM from the PCM/ECU. I've also managed to record the 5 HEX byte code the immobiliser sends back to the ECU/PCM with a logic analyser (it's intermittent, but I got lucky).

Given the EEPROM dump, is it possible to calculate the 5 HEX byte code the PCM/ECU is expecting?

I've built a small microcontroller circuit that can replace the immobiliser box, but where the box has failed completely, I cannot read the 5 byte HEX code that I need to send to the PCM/ECU. I assume the PCM/ECU does this calculation internally when it receives the HEX code, to confirm it's correct. I just need to calculate it manually, so I can program it into my microcontroller circuit.

I've attached the EEPROM dump, and the 5 byte HEX code returned by the immobiliser is C2 21 AE 8A E4.

I believe the PIN code from the EEPROM dump is 84 75 51 27.

Thanks in advance.

EEPROM read.zip
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