Monitor Description
WARNING: This page is about a different car, the 2007 Toyota Land Cruiser. However, it is still accessible from the selected car via links, so may be relevant.
This DTC indicates that the 1-2 shift valve in the valve body is locked in the direction that the spring compresses.
The ECM commands gear shifts by turning the shift solenoid valves ON/OFF and controls the oil pressure applied to the valves in the valve body.
The ECM calculates the actual transmission gear by comparing the signals from the input speed sensor (NT) and the output speed sensor (SP2). The ECM can detect mechanical problems in the shift solenoids, valve body and automatic transmission (clutch, brake, gear etc.). If the ECM detects that the actual gear position and the commanded gear position are different, it will illuminate the MIL and store the DTC.