Figured out the '90 240 fault

I'd posted a while back about a '90 244 with the check engine light on.
I got 213 and 231. Checked the throttle switch and wiring, verified that
to be good. Problem turned out to be with the ECU itself, swapped in a
known good one from another car and all the problems went away.

Experience has shown it to be extremely rare for ECUs to fail, I'd only
ever had to fix one once, a Bosch in an old VW that had a shorted
capacitor in the power supply, but now I read that LH 2.4 boxes are
failing fairly often and the salvage yards are picked clean. The LH 2.4
uses one of those stupid ceramic thin film hybrid modules which is
effectively impossible to repair, and go figure that's where the issue
seems to be. I can trace the TPS signal into that and that's where it
ends. Don't suppose anyone has ever reverse engineered one? ECU info
seems to be very hard to come by. I may draw up a schematic of the dead
one, but the hybrid module is a tough one, two IC dies on it that
obviously would be very difficult to identify. I fixed a 2.2 ECU
recently that was my own fault for plugging the AIC valve connector into
the TPS of a 740, they are entirely standard off the shelf components,
so not likely to run into this sort of issue.