P0781
A750E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: P0781: 1-2 Shift (1-2 Shift Valve)
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 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
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
NOTICE:
Perform the universal trip to clear permanent DTCs Reading and Clearing Diagnostic Trouble Codes.
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 / Engine and 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 Automatic Transmission System - A750E
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 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 Reading and Clearing Diagnostic Trouble Codes.
(c) Warm up the engine.
(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 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 the Techstream.
OK:
Gear position changes in accordance with the Techstream command.
NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.
3. PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT) P0746
NG -- REPLACE SHIFT SOLENOID VALVE SLT Disassembly
OK -- Continue to next step.
4. CLEAR DTC AND PERFORM RUNNING TEST
(a) Clear the DTCs Reading and Clearing Diagnostic Trouble Codes.
(b) Check for DTCs again after conducting the Monitor Drive Pattern Monitors, Trips, Drive Cycles and Readiness Codes.
OK:
No DTC code output.
NG -- REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Removal
OK -- END