Fail-Safe Chart: Fail-Safe

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

1. ATF (Automatic Transmission Fluid) temperature sensor:

   When the ATF temperature sensor has a malfunction, 5th upshift is prohibited.

2. Counter gear speed sensor NC (Speed sensor NC):

   When the counter gear speed sensor has a malfunction, 5th upshift is prohibited.

3. Shift solenoid valve DSL:

   When the solenoid valve DSL has a malfunction, the current to the solenoid valve is stopped. This stops lock-up control, then fuel economy decreases.

4. Shift solenoid valve SL1, SL2, SL3 and S4:

   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" in order to shift into the gear positions shown in the figure Fig 1 below.

   Manual shifting as shown in the following table must be done (In case of a short circuit, the ECM stops sending the current to the short circuit solenoid).

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

   Circle: ON, Traingle: According to Flex Lock-up, X: OFF

   -->: Condition in the normal operation is shown on the left of "-->".

   Condition in the fail-safe mode is shown on the right of "-->".

   Fig 1: Fail-Safe Mode Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002