P0781
A760H AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM (for 2GR-FSE): P0781: 1-2 Shift (1-2 Shift Valve)
P0781 - 1-2 Shift (1-2 Shift Valve)
SYSTEM DESCRIPTION
The 1-2 shift valve performs shifting to 1st gear and other gears.
HINT
- Gear positions in the event of a solenoid valve mechanical problem:
N*: Neutral
- Gear position during fail-safe operation:
If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown in the table below.
*1: Under engine braking, downshifting to 1st or 2nd gear is prohibited.
MONITOR DESCRIPTION
This DTC indicates that the 1-2 shift valve in the valve body is locked in the direction the spring compresses.
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
The following items are common to all conditions below.
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)
Malfunction (A):
Malfunction (B):
Malfunction (C):
Malfunction (D):
INSPECTION PROCEDURE
NOTICE:
Perform the universal trip to clear permanent DTCs DTC Check / Clear.
PROCEDURE
1. CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0781)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) position and push the Techstream main switch ON.
(c) When you use Techstream:
Select the item "Powertrain / ECT / Trouble Codes".
(d) 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
HINT
Using the Techstream to perform Active Test 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 Test early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Test.
(a) Warm up the engine.
(b) Turn the engine switch off.
(c) Connect the Techstream to the DLC3.
(d) Turn the engine switch on (IG) position.
(e) Turn the Techstream on.
(f) Select the item "Powertrain / ECT / Active Test".
(g) According to the display on tester, 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.
HINT
- This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
- The 4th to 5th and 5th to 6th up-shiftings must be performed with the accelerator pedal released.
- The 6th to 5th and 5th to 4th down-shiftings 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 (Shift Status) display on the Techstream.
- Gear positions in the event of a solenoid valve mechanical problem:
N*: Neutral
OK:
Gear position changes in accordance with the tester command.
NG -- 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 (Automatic Transmission Fluid) temperature: 50 to 80°C (122 to 176°F)
- Be careful to prevent SST hose from interfering with the exhaust pipe.
- This check must be conducted after checking and adjusting engine.
- Perform under condition that A/C is OFF.
HINT
Using the Techstream to perform Active Test 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 Test early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Test.
(a) Turn the engine switch off.
(b) Lift the vehicle up.
(c) Remove the test plug on the transmission case center right side and connect SST.
SST : 09992-00095
09992-00231
09992-00271
(d) Lower the vehicle.
(e) Fully apply the parking brake and chock the 4 wheels.
(f) Connect the Techstream to the DLC3.
(g) Start the engine.
(h) Warm up the ATF (Automatic Transmission Fluid).
(i) Measure the line pressure when the engine is idling.
(j) Turn the Techstream on.
(k) Select the item "Powertrain / ECT / Active Test".
(l) According to the display on tester, perform the "Active Test".
(m) Measure the line pressure with SST.
*: "Activate the Solenoid (SLT)" in the Active Test is performed to check the line pressure changes by connecting the SST to the automatic transmission, which is used in the HYDRAULIC TEST Hydraulic Test as well.
HINT
The pressure values in Active Test and HYDRAULIC TEST are different from each other.
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 DTC again after conducting the "MONITOR DRIVE PATTERN FOR ECT TEST" Monitors, Trips, Drive Cycles and Readiness Codes.
OK:
No DTC code
NG -- REPLACE TRANSMISSION VALVE BODY ASSEMBLY
OK -- END