Learn the top signs of a faulty Transmission Control Module (TCM) and its replacement cost. Keep your car running smoothly with our expert advice.

The transmission control module in my 2007 Mazda 3 is playing up, I was wondering if I can just replace it with another one from a Mazda the same year and make. I've been told it has to be coded ...

To convince the transmission control module that a working automatic was still installed and clear the fourteen-odd diagnostic codes, [Dean] put together a block of eight common automotive relays.

Comparing features of the latest stand-alone automatic transmission control modules. Which one will work best for your transmission? Jeff Smith breaks it down.

The power control module, aka PCM, manages the engine, transmission and other systems based on information it receives from various sensors around the vehicle.