|This programming extension harness is to be used with one of our switch assemblies to reprogram the T43 transmission control module. A CAN termination resistor is included with this harness so that an ECM is not required for programming. BE AWARE that GM may require the TCM to be programmed with the ECM if using TIS-SPS programming. If using our Professional Series solution, adapter harness EFI# 100-00733 is required for a direct connection into the switch assembly. No adapter harness is needed if using our Hobbyist Series solution.