6T40 Transmission Control Module TCM 24260820

This is the external transmission control module (TCM) for the GM 6T40 and 6T45 six-speed front-wheel-drive automatics, replacing GM part number 24260820. The module bolts to the top of the transmission case and plugs into the internal case connector, and it is what commands the shift solenoids, line pressure and torque converter clutch apply. The manufacturer lists it for Chevrolet Cruze, Buick Regal and GMC Terrain applications - match the number stamped on your existing module to 24260820 before ordering, because GM used several part numbers across this transmission family.

It ships unprogrammed. A replacement TCM has to be VIN-programmed with GM software before the car will start and shift, so plan on a dealer or a shop with a GM-capable scan tool doing the setup and, on most of these, a transmission adaptive relearn afterward. Budget for that step - the module is not plug-and-play.

The failure pattern on 6T40 and 6T45 units is usually a no-communication or intermittent-shift complaint rather than a mechanical one: P0700 with U0101 lost communication with the TCM, solenoid circuit codes, a hard 1-2 shift, converter clutch shudder that never clears, or the car dropping into limp with third gear only. Heat cycling on top of the case cracks the internal solder joints, so the fault often comes and goes and is worse once the transmission is hot. Before you replace it, pull the case connector and look for fluid wicking up the harness - a leaking case connector seal will fill the new module and kill it the same way, so fix that first.