A few days late here, but…..did you get the problem figured out?
I’d suspect it’s not communicating with the SPU. What was the issue with the previous board? There is also a communication board check you can do too utilizing the Wizard program. “CMC” I think is the command (enter).
What faults are present when you run the Wizard program?
Double check all connections from the EPU Link and terminal strip on the cart top and associated wiring in MR.
Are there any pico type fuses on the EPU Link board? Voltages are good?
Will the car run on inspection from the machine room? Or on car top inspection?
