Another Drive Controller dead

[JACIII1]

Have replaced 3 drive controllers for failure. Each time thinking I found the problem.

All failures come with no self check error light sequence and no error codes. ie not LED indication whatsoever. Tractor does not move or report errors.

1) failed - original. Attributed to age (wear) 2002 model tractor.
2) failed 13 months later - JD Dealer advised rebuild alternator and replace diode. Suspected some reverse polarity current flow.
3) failed 6 months later - no code light or self check light. Got some output with vom from light wires indicating a very weak "sensor supply voltage".

Am at my wit's end with this thing. Have done the usual searches here and other tractor sites.

Any help or suggested avenues (up to and including "trade it off!" are appreciated.

Thanks,
Jim