Toyota 4Runner: Fail-safe Chart

Toyota 4Runner Service Manual / Drivetrain / A750e Automatic Transmission / Transaxle / Automatic Transmission System / Fail-safe Chart

FAIL-SAFE CHART

1. 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
D S5	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
S4	1st	ON	OFF	OFF	OFF	ON
	2nd	ON	ON	OFF	OFF	ON
	3rd	OFF	ON	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
S3	1st	ON	OFF	OFF	OFF	ON
	2nd	ON	ON	OFF	OFF	ON
	3rd E/B	OFF	ON	OFF	OFF	OFF
S2	1st	ON	OFF	OFF	OFF	ON
S2	2nd E/B	ON	ON	ON	OFF	OFF
S1	1st E/B	ON	OFF	OFF	OFF	OFF

2. 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:

Electrical malfunction: Condition is shown above the "↓".
Fail-safe mode: Condition is shown below the "↓".
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
D S5	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
S4	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
S3	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
S2	1st	OFF	OFF	OFF	OFF	ON
S2	3rd E/B	OFF	ON	ON	OFF	OFF
S1	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
D S5	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
S4	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
S3	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
S2	1st	ON	OFF	OFF	OFF	ON
S2	2nd E/B ↓ 4th	ON ↓ OFF	OFF	ON	OFF	OFF ↓ ON
S1	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
D S5	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
S4	1st	ON	OFF	OFF	OFF	ON
	2nd	ON	ON	OFF	OFF	ON
	3rd	OFF	ON	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
S3	1st	ON	OFF	OFF	OFF	ON
	2nd	ON	ON	OFF	OFF	ON
	3rd E/B ↓ 3rd	OFF	ON	OFF	OFF	OFF ↓ ON
S2	1st	ON	OFF	OFF	OFF	ON
S2	2nd	ON	ON	OFF	OFF	OFF
S1	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
D S5	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
S4	4th	OFF	OFF	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
S3	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
S2	1st	OFF	OFF	OFF	OFF	ON
S2	Fail 4th	OFF	OFF	ON	OFF	OFF ↓ ON
S1	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
D S5	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
S4	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
S3	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
S2	1st	ON	OFF	OFF	OFF	ON
S2	1st E/B ↓ 1st	ON	OFF	OFF	OFF	OFF ↓ ON
S1	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
D S5	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
S4	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
S3	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
S2	1st	OFF	OFF	OFF	OFF	ON
S2	2nd	OFF	ON	OFF	OFF	OFF
S1	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
D S5	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
S4	4th	OFF	OFF	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
	4th	OFF	OFF	OFF	OFF	ON
S3	3rd	OFF	OFF	OFF	OFF	ON ↓ ON
	3rd	OFF	OFF	OFF	OFF	ON ↓ ON
	3rd E/B ↓ 3rd	OFF	OFF	OFF	OFF	OFF ↓ ON
S2	1st	OFF	OFF	OFF	OFF	ON
S2	1st E/B ↓ 1st	OFF	OFF	OFF	OFF	OFF ↓ ON
S1	1st E/B	OFF	OFF	OFF	OFF	OFF

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