Thinking out loud -
Check the ground connections, especially at/near the TIPM
Check all the multipin connectors that plug into the TIPM for loose/floating pins, corrosion, bent pins, etc.
Check the wiring harnesses near the TIPM for signs of physical (mechanical) damage.
This is sounding like either of -
a) poor ground connection (emphasis on TIPM ground)
b) Can C bus problem (Open or shorted).