P0781
A750E AUTOMATIC TRANSMISSION SYSTEM (for 2UZ-FE): P0781: 1-2 Shift (1-2 Shift Valve)
DTC P0781 - 1-2 Shift (1-2 Shift Valve)
DESCRIPTION
The 1-2 shift valve performs shifting to 1st gear and other gears.
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.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All
Condition (A)
Condition (B)
Condition (C)
Condition (D)
TYPICAL MALFUNCTION THRESHOLDS
Both of the following conditions are met: Condition (A) and Condition (B), (C) or (D)
Condition (A)
Condition (B)
Condition (C)
Condition (D)
INSPECTION PROCEDURE
PROCEDURE
1. CHECK DTC OUTPUT (IN ADDITION TO DTC P0781)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON.
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / ECT / Trouble Codes.
(e) Read the DTCs using the Techstream.
Result
HINT: If any other codes besides P0781 are output, perform troubleshooting for those DTCs first.
B -- GO TO DTC CHART
A -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (RUNNING TEST)
CAUTION: This test should always be performed with at least 2 people.
NOTICE:
- 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.
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 DTC (DTC Check / Clear).
(c) Warm up the engine.
(d) Enter the following menus: Powertrain / 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 (Fail-Safe Chart).
ECT:
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.
NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY
OK -- Continue to next step.
3. PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT)
NOTICE:
- Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).
- Be careful to prevent SST's hose from interfering with the exhaust pipe.
- Perform the test with the A/C 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) Remove the test plug on the transmission case center right side and connect SST.
SST: 09992-00095
09992-00231
09992-00271
(b) Connect the Techstream to the DLC3.
(c) Start the engine and warm it up.
(d) Measure the line pressure with SST.
(e) Turn the Techstream on.
(f) Enter the following menus: Powertrain / ECT / Active Test.
(g) According to the display on the Techstream, perform the Active Test.
(h) Measure the line pressure.
ECT:
HINT: *: 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 (Hydraulic Test) 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.
NG -- REPLACE SHIFT SOLENOID VALVE SLT
OK -- Continue to next step.
4. CLEAR DTC AND PERFORM RUNNING TEST
(a) Clear the DTC (DTC Check / Clear).
(b) Check for DTC again after conducting the MONITOR DRIVE PATTERN (Monitors, Trips, Drive Cycles and Readiness Codes).
OK:
No DTC code output.
NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY
OK -- END