How to Change a TCM in a 2007 Impalaby Kyle Sanstrom
The transmission control module, or TCM, in a 2007 Chevrolet Impala is designed to control all of the electronic components that operate the transmission. The TCM also communicates with the powertrain control module, or PCM, in order to seamlessly coordinate the operation of the transmission with other vehicle systems. When the TCM fails, the transmission may shift erratically, harshly, or become unresponsive. Replacement TCMs are available from certified General Motors dealerships.
Turn off the engine and disconnect the negative battery cable, using a battery terminal wrench. Remove the engine oil fill cap, and place a clean rag inside the fill hole to prevent dirt and debris from entering the engine while the cap is removed.
Pull up on the intake manifold cover in order to separate the cover from the retaining studs, then set the cover aside. Disconnect the positive crankcase ventilation tube from the air intake tube.
Loosen the air cleaner intake tube clamp at the throttle body, using a flat-head screwdriver. Disconnect the air cleaner intake tube from the throttle body. Loosen the air cleaner intake tube clamp from the mass airflow sensor. Disconnect the air cleaner intake tube from the mass airflow sensor and set it aside.
Separate the engine control module from its bracket by depressing the plastic tabs holding the module to the bracket. Swing the ECM out of the way to make room to access the TCM. Do not disconnect the ECM’s electrical connectors.
Disconnect the TCM’s electrical connector and remove the TCM from its bracket by depressing the plastic retaining connectors. Install the new TCM into the retaining bracket and reconnect the electrical connector. Reinstall the ECM into its retaining bracket.
Reconnect the air cleaner intake tube at the throttle body and mass airflow sensor, then tighten the clamps to secure the tube. Reinstall the positive crankcase ventilation hose into the air intake cleaner tube. Reinstall the intake manifold cover and then replace the oil filler cap.
Connect a Tech 2 scan tool to the vehicle’s diagnostic data port. Power on the scan tool, and then select the vehicle’s year and body type (W). Navigate to the special functions menu and reset the transmission adaptive pressure, or TAP, information. Disconnect the scan tool once the procedure is complete and road test the vehicle.
- When the TCM is replaced, the TAP must be reset in order clear out any data from the old TCM. This allows the PCM to re-learn the transmission shift points and sync with the new TCM. Transmission performance can be affected during this time, but should return to normal within a few drive cycles.
- The Tech 2 is General Motors’ factory scan tool. Aftermarket scan tools are not capable of communicating with the PCM at the level necessary to reset the TAP. You must have access to a Tech 2 in order to complete this procedure properly.