Fail-Safe Chart

FAIL-SAFE

This function minimizes the loss of the ECT functions when any malfunction occurs in each sensor or solenoid.

FUNCTION CHART

Malfunction Part

Function

DTC P0717:
Input Speed Sensor (NT)

During an input speed sensor malfunction, shift control is effected through the output speed sensor signal (SP2).
During an input speed sensor malfunction, up-shift to the 5th and 6th, AI-SHIFT ⁽¹⁾ and flex lock-up clutch control are prohibited.

DTC P0500:
Output Speed Sensor (SP2)

During an output speed sensor malfunction, shift control is effected through the input speed sensor signal (NT).
During an output speed sensor malfunction, up-shift to the 5th and 6th, AI-SHIFT ⁽¹⁾ and flex lock-up clutch control are prohibited.

DTC P0710, P0712, P0713:
ATF Temp. Sensor

During an ATF temperature sensor malfunction, up-shift to the 5th and 6th and flex lock-up clutch control are prohibited.
Shift Solenoid Valve S1, S2, S3, S4 and SR The current to the failed solenoid valve is cut off and control is effected by operating the other solenoid valves.
Shift control is effected depending on the failed solenoid as described in the table in Fig 1 and Fig 2.

DTC P0748, P0778:
Shift Solenoid Valve SL1 and SL2

During a solenoid valve SL1 or SL2 malfunction, up-shift to the 5th and 6th and flex lock-up clutch control are prohibited.

DTC P2757, P2759:
Shift Solenoid Valve SLU

During a solenoid valve SLU malfunction, the current to the solenoid valve is stopped. This stops lock-up control and flex lock-up control, fuel economy decreases.

DTC P2714, P2716:
Shift Solenoid Valve SLT

During a solenoid valve SLT malfunction, the current to the solenoid valve is stopped. This stops line pressure optimal control, the shift shock increases. However, shifting is effected through normal clutch pressure control.

⁽¹⁾	AI (Artificial Intelligence) -SHIFT control

In addition to the switching of the shift pattern through the pattern select switch, the AI-SHIFT control enables the ECM to estimate the road conditions and the driver's intention in order to automatically select the optimal shift pattern. As a result, a comfortable ride has been realized.

Fail-safe operation for electronically malfunctioning shift solenoid valve (S1, S2, S3, S4 and SR):
HINT:

Fail-safe operation in the event of an electric system malfunction.

Fail safe function:

If either of the shift solenoid valve circuits has an open or short failure, the ECM turns the other shift solenoid "ON" and "OFF" in order to shift into the gear positions shown in the table below.

In case of a short circuit, the ECM stops sending current to the short circuited solenoid.

Even if starting the engine again in the fail-safe mode, the gear position remains in the same position.

Fig 1: Fail Safe Chart - Electrical Malfunction (1 Of 2)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Fail Safe Chart - Electrical Malfunction (2 Of 2)
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fail-safe operation for mechanically malfunction:
HINT:

Fail-safe operation in the event of a mechanical system malfunction.

Fail safe function:

The ECM controls the gear position as shown in Fig 3 when malfunctions occur.

Fig 3: Fail Safe Chart - Mechanical Malfunction
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002