Q: My car is jerking for an unknown reason

Hey there. This may be a sign of a failing transmission control module or low transmission fluid. The transmission control module (TCM) helps regulate fuel efficiency and power while storing information about the transmission system in its memory. A faulty transmission control module may cause the car not to increase its speed even when pressing the gas pedal and may respond poorly when you shift the gear into drive.

The transmission control module has various sensors such as vehicle speed sensors, wheel speed sensors, throttle position sensors, turbine speed sensor, and transmission fluid temperature sensors that all direct information to it in order for it to perform it’s function. Other components controlled by the the TCM include a kick down switch, traction control system, and cruise control module.

Any of these may also affect the way the transmission control module performs and controls the transmission and the shifting of your car. When this is not working properly, you may notice harsh shifting or delays in shifting. If you would like to have this scoped out, a certified professional from YourMechanic can come to your car’s location to diagnose the jerking problem and follow through with repairs.