P0781
A750E AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM (for 1GR-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 the spring is compressed.
The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF" and switching oil pressure 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 many mechanical problems in the shift solenoids, valve body, and the transmission clutches, brakes, and gears. 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 OTHER DTCS OUTPUT (IN ADDITION TO DTC P0781)
(a) Connect Techstream to the DLC3.
(b) Turn the ignition switch ON, and turn the tester main switch ON.
(c) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(d) Read the DTCs using 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)
HINT: Performing Techstream's Active Test allows relays, VSVs, actuators and other items to be operated without removing any parts. Performing the Active Test early in troubleshooting is one way to save time.
The Data List can be displayed during the Active Test.
(a) Warm up the engine.
(b) Turn the ignition switch OFF.
(c) Connect Techstream to the DLC3.
(d) Turn the ignition switch ON, and turn the tester main switch ON.
(e) Enter the following menus: Powertrain / Engine and ECT / Active Test.
(f) Perform the Active Test using Techstream.
HINT:
While driving, the shift position can be forcibly changed with Techstream.
Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem Fail-Safe Chart.
Engine and 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 Techstream.
OK:
Gear position changes in accordance with the tester 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: Performing Techstream's Active Test allows relays, VSVs, actuators and other items to be operated without removing any parts. Performing the Active Test early in troubleshooting is one way to save time.
The Data List can be displayed during the Active Test.
(a) Remove the test plug on the transmission case center right side and connect SST.
SST: 09992-00095
09992-00231
09992-00271
(b) Connect Techstream to the DLC3.
(c) Start the engine and warm it up.
(d) Measure the line pressure with SST.
(e) Turn Techstream ON.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.
(g) Follow the instructions on the tester and perform the Active Test.
(h) Measure the line pressure with SST.
Engine and 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. Please 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 THE DTC AND RUNNING TEST
(a) Clear the DTC, and check for the DTC again after conducting the " MONITOR DRIVE PATTERN FOR ECT TEST" Monitors, Trips, Drive Cycles and Readiness Codes.
OK:
No DTC code
NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY
OK -- END