Location of the TCM. Does a used one from another CTS need to be reprogrammed?
Does this this cause a engine reduce power message?
The engine reduce power message has to do with the TAC system. Throttle Actuator Control(TAC) is your electronically controlled throttle. In most cases the the throttle body(TAC System) will need to be replaced. In some cases a software update may cure the issue. And in rare occasions simply unplugging the battery for a few minutes works.
For whatever reason you want to swap out the TCM with a used one, you may need to reprogram it.
Transmission Control Module(TCM)
TCM(8) is located at the right front of engine compartment.
Transmission Control Module Programming and Setup
The transmission control module (TCM) must be programmed with the proper software/calibrations. Ensure that the following conditions exist in order to prepare for TCM programming:
– The battery is fully charged.
– The ignition switch is in the RUN position.
– The Techline equipment cable connection at the data link connector (DLC) is secure.
Program the TCM using the latest software matching the vehicle.
If the TCM fails to program, proceed as follows:
Ensure that the TCM connection is OK.
Inspect the Techline equipment for the latest software version.
Attempt to program the TCM. If the TCM still cannot be programmed properly, replace the TCM.