P0781

A750E AUTOMATIC TRANSMISSION: 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 of the spring compression. The ECM controls the gearshifts 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

Condition (A) and Conditions (B), (C) or (D) are met:

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 ANY OTHER DTCS 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 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 (CONTROL THE SHIFT POSITION)

HINT
Performing the Active Test using a Techstream allows components, such as the relay, VSV, and actuator, to be operated without removing any parts. Performing the Active Test as a first step of troubleshooting is one method of shortening labor time.

It is possible to display the Data List during the Active Test.

(a) Warm up the engine.
(b) Turn the ignition switch off.
(c) Connect the Techstream to the DLC3.
(d) Turn the ignition switch to ON.
(e) Turn the Techstream on.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.
(g) According to the display on the Techstream, perform the Active Test.

HINT
While driving, the shift position can be changed with the Techstream.

Comparing the shift position directed by the Active Test with the actual shift position enables the problem to be confirmed Fail-Safe Chart.

Engine and ECT





HINT
* This test can be conducted when the vehicle speed is 50 km/h (30 mph) or less.
* The 4th to 5th up-shifting must be performed with the accelerator pedal released.
* The 5th to 4th down-shifting 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 directed 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 operation.

NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.

3. PERFORM ACTIVE TEST USING TECHSTREAM (ACTIVE THE SOLENOID (SLT)) P0746

NG -- REPLACE SHIFT SOLENOID VALVE SLT Disassembly
OK -- Continue to next step.

4. CLEAR DTC AND PERFORM RUNNING TEST

(a) Clear the DTC Reading and Clearing Diagnostic Trouble Codes.

(b) Check for the DTC 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