Possible causes of automatic transmission jerking when switching from 1 to 2:
Problems with the valve body:
* Contamination or clogging of the valve body
* Wear of solenoids
* Malfunction of automatic transmission control module
Problems with torque converter:
* Wear of friction linings
*Low transmission fluid level
* Transmission fluid contamination
* Pump faults
Mechanical problems:
* Wear of clutches in gear shift package 1-2
* Worn drum or shift shaft
* Shift piston slippage 1-2
Electronic problems:
*Speed sensor malfunction
* Malfunction of the throttle position sensor
*Engine control unit malfunction
Other possible reasons:
* Incorrect adjustment of the automatic transmission selector cable
* Dirty or clogged transmission fluid filter
*Low transmission fluid pressure
* Worn gaskets or seals
* Air in the transmission system
Diagnosis and elimination:
It is recommended that you contact a qualified mechanic to diagnose and repair the problem. Diagnostics may include:
* Checking trouble codes (DTC) using a scanner
*Transmission fluid pressure measurement
* Testing solenoids and valve body
* Removal and inspection of the mechanical part of the automatic transmission
Troubleshooting may include replacing or repairing faulty components such as the valve body, solenoids, clutches, torque converter or electronic control unit.