Reasons why an automatic transmission may jerk when braking:
Transmission problems:
* Worn or damaged clutches or brake band.
* Faulty shift solenoid.
* Problems with the torque converter.
* Low or old gear oil level.
Engine problems:
* Unstable idle speed.
* Faulty engine sensors (such as MAF sensor or lambda probe).
* Problematic spark plugs or high voltage wires.
Electronics problems:
* Faulty throttle position sensor.
* Malfunction of the transmission control module (TCM).
* Poor electrical connections.
Other possible reasons:
* Clogged fuel filter.
* Poor battery contact.
* Worn engine or transmission mounts.
* Worn brake disc or pads.
* Faulty ABS sensor.
What to do if the automatic transmission jerks when braking:
* Check the level and condition of the transmission oil.
* Have your transmission diagnosed and repaired by an experienced mechanic.
* Check the motor and electronics for faults.
* Replace faulty components as needed.