Functioning of the automatic transmission in emergency mode
While the vehicle is moving, if a malfunction occurs in the sensors and solenoids listed below, the emergency operation of the automatic transmission may turn on.
Vehicle speed sensor 1 (automatic transmission secondary shaft speed sensor)
In the event of a malfunction of this sensor, its signal is replaced by the vehicle speed sensor 2 signal for the instrument cluster.
Accelerator sensor
In the event of a malfunction of this sensor, the control unit uses the signals from the idle switch and from the switch for fully depressing the accelerator pedal and uses them to set the degree of depression on the accelerator pedal and line pressure, see table.
Range switch
If the automatic transmission control unit receives two or more signals from the range switch, the control unit selects one of the positions D, N, R, 2 and 1, depending on the priority determined within the unit. However, when returning to normal operation, shifting to 4th gear is blocked. In addition, depending on the state in the range switching valve circuit, the current driving state of the vehicle is determined as shown in the table.
Shift solenoids A and B
If the gearbox control unit receives an abnormal signal from the solenoid, gear shifting occurs as follows:
O: Solenoid ON.
X: Solenoid OFF
-: Abnormal signal
Line pressure control solenoid
If an abnormal signal is received from the solenoid to the automatic transmission control unit, the solenoid is turned off and the maximum pressure signal in the line is set.
Torque Converter Clutch Lockup Solenoid
If an abnormal signal is received from the solenoid to the automatic transmission control unit, the solenoid is turned off and the torque converter lockup is released.
Engine Brake Clutch Solenoid
If an abnormal signal is received from the solenoid to the automatic transmission control unit, the solenoid is turned off. During deceleration, engine braking will occur.