AUTOMATIC TRANSMISSION SYSTEM(for 1GR-FE), Diagnostic DTC:P0781

DTC Code	DTC Name
P0781	1-2 Shift (1-2 Shift Valve)

DESCRIPTION

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

DTC Code	DTC Detection Condition	Trouble Area
P0781	The gear required by the ECM does not match the actual gear when driving (2 trip detection logic1, 1 trip detection logic2).	Valve body is blocked up or stuck (1-2 shift valve) Shift solenoid valve SLT remains open or closed Automatic transmission (clutch, brake or gear, etc.)

*1: w/ OBD
*2: w/o OBD

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 the 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 the commanded gear position are different, it will illuminate the MIL and store the DTC.

PROCEDURE

CHECK DTC OUTPUT (IN ADDITION TO DTC P0781)

Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG).
Turn the intelligent tester on.
Enter the following menus: Powertrain / Engine and ECT / DTC.

Read the DTCs using the tester.

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

Tech Tips

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

GO TO DTC CHART Click here

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (RUNNING TEST)

CAUTION:

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

Note

Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).
Perform the test with the A/C turned off.

Tech Tips

Using the intelligent tester 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.

Connect the intelligent tester to the DLC3.
Clear the DTC Click here.
Warm up the engine.
Enter the following menus: Powertrain / Engine and ECT / Active Test.

According to the display on the tester, perform the Active Test.

Tech Tips

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

Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem Click here.

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	It is possible to check the operation of the shift solenoid valves. [Vehicle Condition] The vehicle speed is 50 km/h (31 mph) or less.

Tech Tips

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 tester.

OK
Gear position changes in accordance with the tester command.

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Click here

PERFORM ACTIVE TEST USING INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT)

Note

Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).
Be careful to prevent SST hose from interfering with the exhaust pipe.
Perform the test with the A/C turned off.

Tech Tips

*1 Test Plug

Remove the test plug on the transmission case center right side and connect SST.

SST

09992-00095 ( 09992-00231, 09992-00271 )
Connect the intelligent tester to the DLC3.
Start the engine and warm it up.
Measure the line pressure with SST.
Turn the intelligent tester on.
Enter the following menus: Powertrain / Engine and ECT / Active Test.
According to the display on the tester, perform the Active Test.

*1	Test Plug

Measure the line pressure.

Engine and ECT
Tester Display	Test Part	Control Range	Diagnostic Note
Activate the Solenoid (SLT)*	Operate shift solenoid valve SLT and raise line pressure	ON or OFF Tech Tips OFF: Line pressure up (when Active Test "Activate the Solenoid (SLT)" is performed, ECM commands shift solenoid valve SLT to turn OFF) ON: No action (normal operation)	[Vehicle Condition] The vehicle is stopped. The engine is idling.

Tech Tips

*: Activate the Solenoid (SLT) in the Active Test is performed to check the line pressure changes by connecting SST to the automatic transmission, which is used in the Hydraulic Test Click here as well. Note that the pressure values in the Active Test and hydraulic test are different.

OK
The line pressure changes as specified when performing the Active Test.

REPLACE SHIFT SOLENOID VALVE SLT Click here

CLEAR DTC AND PERFORM RUNNING TEST
1. Clear the DTC Click here.
2. Check for DTC again after conducting the Monitor Drive Pattern Click here.
  
  OK
  
  No DTC output
OK
END

NG
REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Click here