Automatic Transmission System (For 1Gr-Fe) Fail-Safe Chart

Drivetrain. Hilux. Tgn26, 36 Kun25, 26, 35, 36 Ggn25
A750F Automatic Transmission Transaxle. Hilux. Tgn26, 36 Kun25, 26, 35, 36 Ggn25

  1. FAIL-SAFE

  1. FAIL-SAFE FUNCTION

Automatic Transmission System (For 1Gr-Fe) -- Fail-Safe Chart



FAIL-SAFE
This function minimizes the loss of ECT functions when a malfunction occurs in a sensor or solenoid.

Malfunction Part
Function
No. 1 ATF temperature sensor
During a No. 1 ATF temperature sensor malfunction, up-shift to 5th gear and flex lock-up clutch control are prohibited.
Speed sensor SP2
During an output speed sensor malfunction, shift control is performed using the input speed sensor NT signal.
Shift solenoid valve S1, S2 and SR
The current to the malfunctioning solenoid valve is cut off and control is performed by operating the other normal solenoid valves.
Shift control is performed depending on the failed solenoid as described in the table below.
Shift solenoid valve SL1 and SL2
During a solenoid valve SL1 or SL2 malfunction, up-shift to 5th gear is prohibited.
Shift solenoid valve SLT
During a solenoid valve SLT malfunction, the current to the solenoid valve is stopped. This stops line pressure optimal control, and shift shock increases. However, shifting is performed using normal clutch pressure control.
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, and fuel economy decreases.

Shift Solenoid Valve Normal Operation Chart
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
ON
OFF
OFF
OFF
ON
D
1st
ON
OFF
OFF
OFF
ON
2nd
ON
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
5th
OFF
OFF
ON
ON
OFF
4
1st
ON
OFF
OFF
OFF
ON
2nd
ON
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
1st
ON
OFF
OFF
OFF
ON
2nd
ON
ON
OFF
OFF
ON
3rd E/B
OFF
ON
OFF
OFF
OFF
2
1st
ON
OFF
OFF
OFF
ON
2nd E/B
ON
ON
ON
OFF
OFF
L
1st E/B
ON
OFF
OFF
OFF
OFF

FAIL-SAFE FUNCTION
If any of the shift solenoid valve circuits has an open or short failure, the ECM turns the other shift solenoids 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 when starting the engine again in the fail-safe mode, the gear position remains in the same position.
HINT:
  1. Electrical malfunction: Condition is shown above the "↓".
  2. Fail-safe mode: Condition is shown below the "↓".
  3. E/B: Engine brake.

Fail-safe Operation when Shift Solenoid Valve S1 is Malfunctioning
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
OFF
OFF
OFF
OFF
ON
D
4th
↓
3rd
OFF
OFF
↓
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
5th
OFF
OFF
ON
ON
OFF
4
4th
↓
3rd
OFF
OFF
↓
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
3rd
↓
3rd E/B
OFF
OFF
↓
ON
OFF
OFF
ON
↓
OFF
3rd
↓
3rd E/B
OFF
ON
OFF
OFF
ON
↓
OFF
3rd E/B
OFF
ON
OFF
OFF
OFF
2
1st
OFF
OFF
OFF
OFF
ON
3rd E/B
OFF
ON
ON
OFF
OFF
L
1st E/B
OFF
OFF
OFF
OFF
OFF

Fail-safe Operation when Shift Solenoid Valve S2 is Malfunctioning
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
ON
OFF
OFF
OFF
ON
D
1st
ON
OFF
OFF
OFF
ON
1st
↓
4th
ON
↓
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
5th
OFF
OFF
ON
ON
OFF
4
1st
ON
OFF
OFF
OFF
ON
1st
↓
4th
ON
↓
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
1st
ON
OFF
OFF
OFF
ON
1st
↓
3rd E/B
ON
↓
OFF
OFF
OFF
OFF
ON
↓
OFF
3rd E/B
OFF
OFF
OFF
OFF
OFF
2
1st
ON
OFF
OFF
OFF
ON
2nd E/B
↓
4th
ON
↓
OFF
OFF
ON
OFF
OFF
↓
ON
L
1st E/B
ON
OFF
OFF
OFF
OFF

Fail-safe Operation when Shift Solenoid Valve SR is Malfunctioning
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
ON
OFF
OFF
OFF
ON
D
1st
ON
OFF
OFF
OFF
ON
2nd
ON
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
ON
OFF
4
1st
ON
OFF
OFF
OFF
ON
2nd
ON
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
1st
ON
OFF
OFF
OFF
ON
2nd
ON
ON
OFF
OFF
ON
3rd E/B
↓
3rd
OFF
ON
OFF
OFF
OFF
↓
ON
2
1st
ON
OFF
OFF
OFF
ON
2nd
ON
ON
OFF
OFF
OFF
L
1st E/B
ON
OFF
OFF
OFF
OFF

Fail-safe Operation when Shift Solenoid Valve S1 and S2 are Malfunctioning
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
OFF
OFF
OFF
OFF
ON
D
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
5th
OFF
OFF
ON
ON
OFF
4
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
3rd
↓
3rd E/B
OFF
OFF
OFF
OFF
ON
↓
OFF
3rd
↓
3rd E/B
OFF
OFF
OFF
OFF
ON
↓
OFF
3rd E/B
OFF
OFF
OFF
OFF
OFF
2
1st
OFF
OFF
OFF
OFF
ON
Fail 4th
OFF
OFF
ON
OFF
OFF
↓
ON
L
1st E/B
OFF
OFF
OFF
OFF
OFF

Fail-safe Operation when Shift Solenoid Valve S2 and SR are Malfunctioning
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
ON
OFF
OFF
OFF
ON
D
1st
ON
OFF
OFF
OFF
ON
1st
↓
4th
ON
↓
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
ON
↓
OFF
OFF
↓
ON
4
1st
ON
OFF
OFF
OFF
ON
1st
↓
4th
ON
↓
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
1st
ON
OFF
OFF
OFF
ON
1st
↓
3rd
ON
↓
OFF
OFF
OFF
OFF
ON
↓
ON
3rd E/B
↓
3rd
OFF
OFF
OFF
OFF
OFF
↓
ON
2
1st
ON
OFF
OFF
OFF
ON
1st E/B
↓
1st
ON
OFF
OFF
OFF
OFF
↓
ON
L
1st E/B
ON
OFF
OFF
OFF
OFF

Fail-safe Operation when Shift Solenoid Valve S1 and SR are Malfunctioning
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
OFF
OFF
OFF
OFF
ON
D
4th
↓
3rd
OFF
OFF
↓
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
ON
↓
OFF
OFF
↓
ON
4
4th
↓
3rd
OFF
OFF
↓
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
3rd
OFF
ON
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
3rd
OFF
OFF
↓
ON
OFF
OFF
ON
↓
ON
3rd
OFF
ON
OFF
OFF
ON
↓
ON
3rd E/B
↓
3rd
OFF
ON
OFF
OFF
OFF
↓
ON
2
1st
OFF
OFF
OFF
OFF
ON
2nd
OFF
ON
OFF
OFF
OFF
L
1st E/B
OFF
OFF
OFF
OFF
OFF

Fail-safe Operation when Shift Solenoid Valve S1, S2 and SR are Malfunctioning
Shift Lever Position
Gear
Shift Solenoid S1
Shift Solenoid S2
Shift Solenoid SR
Shift Solenoid SL1
Shift Solenoid SL2
R
R
OFF
OFF
OFF
OFF
ON
D
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
ON
↓
OFF
OFF
↓
ON
4
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
4th
OFF
OFF
OFF
OFF
ON
3
3rd
OFF
OFF
OFF
OFF
ON
↓
ON
3rd
OFF
OFF
OFF
OFF
ON
↓
ON
3rd E/B
↓
3rd
OFF
OFF
OFF
OFF
OFF
↓
ON
2
1st
OFF
OFF
OFF
OFF
ON
1st E/B
↓
1st
OFF
OFF
OFF
OFF
OFF
↓
ON
L
1st E/B
OFF
OFF
OFF
OFF
OFF