Just saying Hi for my first post

Hi to all,
Recently joined this forum to find info on the GM ECU 1228707 for my '89 Lotus Esprit Turbo. Turns out that the car stalled out a few weeks back after driving a short distance. Scan showed error code 42(EST circuit malfunction), after troubleshooting it found the ECU to be the fault. Replaced it with one from a '91 Chevy Beretta and all is well now. However, I would like to dig further into the ECU and diagnose the actual failure. Does anyone have an internal schematic for this 1228707 model ECU? I have the wiring diagram(pinout) for it but not the internal circuitry. Drop me a line and let me know if you're able to help and thanks in advance.
Tom S.
'89 Lotus Esprit Turbo