Shift Solenoid: Description and Operation

SHIFT SOLENOID A/B/C (No.1/No.2/No.3)

SYSTEM DESCRIPTION
The ECM uses signals from the vehicle speed sensor and input/turbine speed sensor to detect the actual gear position (1st 2nd, 3rd, 4th or 5th 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, valve body and automatic transmission assembly.

CIRCUIT DESCRIPTION
Shifting from 1st to 5th is performed in combination with ON and OFF of the shift solenoid valves No.1, No.2 and No.3 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 short, the ECM turns the other shift solenoid ON and OFF to shift to the gear positions shown in the table above. The ECM also turns the shift solenoid valve SLU OFF at the same time. If both solenoids are malfunctioning, hydraulic control cannot be performed electronically and must be done manually.
Manual shifting as shown in the following tables must be done (In the case of a short circuit, the ECM stops sending current to the short circuited solenoid).

SHIFT SOLENOID D (No.4)

CIRCUIT DESCRIPTION
Shift solenoid valve No.4 is controlled by ECM and it switches ON and OFF of the O/D direct switch.

SHIFT SOLENOID E (SL)





SYSTEM DESCRIPTION
The ECM uses the signals from the throttle position sensor and Air-flow meter to monitor the engagement condition of the lock-up clutch.
Then the ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect mechanical trouble of the shift solenoid valve SLU, valve body, torque converter clutch and automatic transmission assembly.