Celica GT Ltd Ed Convertible L4-2164cc 2.2L DOHC MFI (1997)
Shift Solenoid: Description and Operation
Shift Solenoids "A" and "B" (No. 1 and No. 2)
SYSTEM DESCRIPTION
The ECM uses signals from the vehicle speed sensor to detect the actual gear position (1st, 2nd, 3rd or O/D gear). The ECM then compares the
actual gear with the shift schedule in the ECM memory to detect mechanical trouble of the shift solenoid valves and valve body.
CIRCUIT DESCRIPTION
Shifting from 1st to O/D is done in combination with ON and OFF of the shift solenoid valves No.1 and No.2 controlled by ECM. If an open or
short circuit occurs in either of the shift solenoid valves, the ECM controls the remaining normal shift solenoid valve to allow the vehicle to be
operated smoothly (Fail safe function).
Fail Safe Function
If either of the shift solenoid valve circuits develops an open or a short, the ECM turns the other shift solenoid ON and OFF to shift to the gear
positions shown in the table below. The ECM also turns the shift solenoid valve SL OFF at the same time. If both solenoids are malfunction,
hydraulic control cannot be done electronically so it must be done manually.
Manual shifting as shown in the above table must be done. (In the case of a short circuit, the ECM stops sending current to the short circuit
solenoid).
