I have a Raymond 740DR32TT that is throwing either a 45 code or a 4D code during start up. The TPC is not energizing during the self test. So far the relay card and relays have been changed and the TPA has also been changed, I have also swapped the TPC. I can activate the TPC in service mode. I have checked the CAN wires, they have voltages of 2.1v and 2.9V. The CAN negative has also checked out. I dont know if the TPA is just not closing the contactor during start up or if its not getting the signal to tell it to. Any help would be greatly appreciated