Toyota 4Runner: 1-2 Shift (1-2 Shift Valve) (P0781)

Toyota 4Runner Service Manual / Drivetrain / A750e Automatic Transmission / Transaxle / Automatic Transmission System / 1-2 Shift (1-2 Shift Valve) (P0781)

DESCRIPTION

The 1-2 shift valve performs shifting to 1st gear and other gears.

DTC Code	DTC Detection Condition	Trouble Area
P0781	Gear required by the ECM does not match the actual gear when driving (2-trip detection logic).	Valve body is blocked or stuck (1-2 shift valve) Shift solenoid valve SLT remains open or closed Automatic transmission (clutch, brake, gear, etc.)

MONITOR DESCRIPTION

This DTC indicates that the 1-2 shift valve in the valve body is locked in the direction that the spring compresses.

The ECM commands gear shifts by turning the shift solenoid valves ON/OFF and controls the oil pressure applied to the valves in the valve body.

The ECM calculates the actual transmission gear by comparing the signals from the input speed sensor NT and output speed sensor SP2. The ECM can detect mechanical problems in the shift solenoids, valve body and automatic transmission (clutch, brake, gear, etc.). If the ECM detects that the actual gear position and commanded gear position are different, it will illuminate the MIL and store the DTC.

MONITOR STRATEGY

Related DTCs	P0781: Valve body/Functional check
Required sensors/Components	Valve body, Automatic transmission assembly, Speed sensor (NT), Speed sensor (NO), Vehicle speed sensor, Throttle position sensor
Frequency of operation	Continuous
Duration	Condition (A) and (B): 0.4 sec. Condition (C): 3 sec. Condition (D): 0.5 sec.
MIL operation	2 driving cycles
Sequence of operation	None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not stored	P0717 (Turbine speed sensor circuit) P0722 (Output speed sensor circuit) P0973, P0974 (Shift solenoid valve S1 circuit) P0976, P0977 (Shift solenoid valve S2 circuit) P0985, P0986 (Shift solenoid valve SR circuit) P0748 (Shift solenoid valve SL1 circuit) P0778 (Shift solenoid valve SL2 circuit) P0128 (ECT (Engine Coolant Temperature) sensor circuit) P0327, P0328, P0332, P0333 (KCS sensor circuit)
ETCS (Electric Throttle Control System)	Not system down
Transmission position	"D"
Duration time from shifting "N" to "D"	4 sec. or more
ECT	40°C (104°F) or higher
Spark advance from max. retard timing by KCS control	0° crankshaft angle or more
Engine	Starting

Condition (A)

ECM selected gear	2nd
Duration time from shift command of ECM	2 sec. or more
Vehicle speed	2 km/h (1.2 mph) or more
Output speed	2nd → 1st down shift point or more
Throttle valve opening angle	6.5% or more at 2000 rpm (Conditions vary with engine speed)
Calculated load value	7.75% or more
Following conditions is met: (a), (b), (c), (d) or (e)	-
(a) Turbine speed/Output speed (NT/NO)	3.30 or more, and 7.50 or less (This means actual gear is 1st)
(b) Turbine speed/Output speed (NT/NO)	1.91 or more, and 2.35 or less (This means actual gear is 2nd)
(c) Turbine speed/Output speed (NT/NO)	1.28 or more, and 1.53 or less (This means actual gear is 3rd)
(d) Turbine speed/Output speed (NT/NO)	0.93 or more, and 1.07 or less (This means actual gear is 4th)
(e) Turbine speed/Output speed (NT/NO)	0.65 or more, and 0.79 or less (This means actual gear is 5th)

Condition (B)

ECM selected gear	4th
Duration time from shift command of ECM	2 sec. or more
Vehicle speed	2 km/h (1.2 mph) or more
Throttle valve opening angle	6.5% or more at 2000 rpm (Conditions vary with engine speed)
Calculated load value	7.75% or more
Following conditions is met: (a), (b), (c), (d) or (e)	-
(a) Turbine speed/Output speed (NT/NO)	3.30 or more, and 7.50 or less (This means actual gear is 1st)
(b) Turbine speed/Output speed (NT/NO)	1.91 or more, and 2.35 or less (This means actual gear is 2nd)
(c) Turbine speed/Output speed (NT/NO)	1.28 or more, and 1.53 or less (This means actual gear is 3rd)
(d) Turbine speed/Output speed (NT/NO)	0.93 or more, and 1.07 or less (This means actual gear is 4th)
(e) Turbine speed/Output speed (NT/NO)	0.65 or more, and 0.79 or less (This means actual gear is 5th)

Condition (C)

Current ECM selected gear

5th

Last ECM selected gear

4th

Vehicle speed

(During transition from 4th to 5th gear)

Less than 100 km/h (62.2 mph)

Condition (D)

ECM selected gear

5th

Engine speed - Turbine speed (NE - NT)

(After transition from 4th to 5th gear)

150 rpm or less

Vehicle speed

(After transition from 4th to 5th gear)

Less than 100 km/h (62.2 mph)

TYPICAL MALFUNCTION THRESHOLDS

Both of the following conditions are met: Condition (A) and Condition (B), (C) or (D)

Condition (A)

Turbine speed/Output speed (NT/NO)

3.30 or more, and 7.50 or less

(This means actual gear is 1st)

Condition (B)

Turbine speed/Output speed (NT/NO)

1.28 or more, and 1.53 or less

(This means actual gear is 3rd)

Condition (C)

Turbine speed - Output speed x 4th gear ratio

(NT - NO x 4th gear ratio)

1000 rpm or more

Condition (D)

Turbine speed - Output speed x 5th gear ratio

(NT - NO x 5th gear ratio)

1000 rpm or more

CAUTION / NOTICE / HINT

NOTICE:

Perform the universal trip to clear permanent DTCs (See page ).

PROCEDURE

1.	CHECK DTC OUTPUT (IN ADDITION TO DTC P0781)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) Read the DTCs using the Techstream.

Result

Result	Proceed to
Only P0781 is output	A
P0781 and other DTCs are output	B

HINT:

If any other codes besides P0781 are output, perform troubleshooting for those DTCs first.

GO TO DTC CHART

2.	PERFORM ACTIVE TEST USING TECHSTREAM (RUNNING TEST)

CAUTION:

This test should always be performed with at least 2 people.

NOTICE:

Perform the test while the ATF temperature is 50 to 80°C (122 to 176°F).
Perform the test with the A/C turned off.

HINT:

Using the Techstream to perform Active Tests allows relays, VSVs, actuators and other items to be operated without removing any parts. This non-intrusive functional inspection can be very useful because intermittent operation may be discovered before parts or wiring is disturbed. Performing Active Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

(a) Connect the Techstream to the DLC3.

(b) Clear the DTCs (See page ).

(d) Enter the following menus: Powertrain / Engine and ECT / Active Test.

(e) According to the display on the Techstream, perform the Active Test.

HINT:

While driving, the shift position can be forcibly changed with the Techstream.

Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem (See page ).

Engine and ECT

Tester Display	Test Part	Control Range	Diagnostic Note
Control the Shift Position	Operate shift solenoid valve and set each shift position	Press "→" button: Shift up Press "←" button: Shift down	Possible to check operation of the shift solenoid valves. [Vehicle Condition] 50 km/h (31 mph) or less.

Tester Display

Test Part

Control Range

Diagnostic Note

Control the Shift Position

Operate shift solenoid valve and set each shift position

Press "→" button: Shift up
Press "←" button: Shift down

Possible to check operation of the shift solenoid valves.

[Vehicle Condition]

50 km/h (31 mph) or less.

HINT:

This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
The 4th to 5th up-shift must be performed with the accelerator pedal released.
The 5th to 4th down-shift must be performed with the accelerator pedal released.
Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
The shift position commanded by the ECM is shown in the Data List display on the Techstream.

OK:

Gear position changes in accordance with the Techstream command.

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

3.	PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT)

REPLACE SHIFT SOLENOID VALVE SLT

4.	CLEAR DTC AND PERFORM RUNNING TEST

(a) Clear the DTCs (See page ).

(b) Check for DTCs again after conducting the Monitor Drive Pattern (See page ).

OK:

No DTC output.

END

REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY

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