** The problem is the adapter harness he made was connected to the Stepper Outputs (which is only intended to drive the ICM.

Thanx KevinBlack for the clarifications.

If he otherwise has enough (4) power-IGBT outputs, it's definitely worths to try to remove stepper chip. (replacement chip not needed if he does not need the outputs). The other parts of the board survive in 80+ % of similar cases. If other parts also get damaged, it's very likely to show up anyway (eg. if cannot connect via RS232 port at all). With small chance it might not show up (even with thorough bench-testing), and cause insidious problems later. Although most drivers accept that small chance to live with, obviously it rules out any critical application (especially aircraft), needless to say.

Study [v3 retest-repair] for more options.

I would:

* remove the stepper chip

* start a paper log about the history (serialnr, date, short description of what happened, measurements, fixes)

* give it some test on bench, at least communications

** preferrably also test p259 outputs (eg EC36/4) with resistor + LED or "tacho lock"

** and power-IGBT ign outputs with resistor + LED (or with brakelight bulb)

** than clamp the TO220 drivers.

** after these I'd try on engine. Use 4A fuses for each ignition driver

*** after it passes basic tests, change to 5A for production - if it didn't blow 4A during tests, it might blow 4A during production (if it was near the edge), but it shouldn't blow 5A without a good reason.