AUTOMATIC TRANSMISSION SYSTEM(for 1VD-FTV with DPF), Diagnostic DTC:P0781

DESCRIPTION

• The 1-2 shift valve performs shifting to 1st gear and other gears. When shifting to 2nd and 4th gears is impossible, or when the ECM directs the transmission to switch to 5th and 6th gear and the engine overruns (clutch slips), this DTC is stored.

  DTC Code	DTC Detection Condition	Trouble Area
  P0781	When conditions (a) and (b), or (a) and (c) are met (2 trip detection logic). (a) When the ECM directs the transmission to switch to 2nd gear, the actual gear is shifted to 1st. (b) When the ECM directs the transmission to switch to 4th gear, the actual gear is shifted to 3rd. (c) When the ECM directs the transmission to switch to 5th gear, the engine overruns (clutch slips).	Valve body is blocked up or stuck (1-2 shift valve) Shift solenoid valve SLT remains open or closed Automatic transmission (clutch, brake or gear, etc.)

  Tech Tips

  
  

  • Gear positions in the event of a solenoid valve mechanical problem:

    ECM gear shift command	1st	2nd	3rd	4th	5th	6th
    Actual gear position under malfunction	1st	1st	3rd	3rd	N*	N*

    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.

  Gear position under normal conditions	1st	2nd	3rd	4th	5th	6th
  Actual gear position under fail-safe mode	1st*	1st*	3rd	3rd	3rd	3rd

  1st*: 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 with the shift solenoids, valve body, 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.

PROCEDURE

1. CHECK DTC OUTPUT (IN ADDITION TO DTC P0781)

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the ignition switch to ON.

   3. Turn the GTS on.

   4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

   5. Read the DTCs using the GTS.

      Result

      Result	Proceed to
      Only P0781 is output	A
      P0781 and other DTCs are output	B

      Tech Tips

      If any other codes besides P0781 are output, perform troubleshooting for those DTCs first.

   
   

   B

   GO TO DTC CHART Click here

   A

2. PERFORM ACTIVE TEST USING GTS (RUNNING TEST)

   CAUTION:

   This test should always be performed with at least 2 people.

   Note

   
   

   • 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.

   Tech Tips

   Using the GTS 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.

   
   

   1. Connect the GTS to the DLC3.

   2. Clear the DTC Click here.

   3. Warm up the engine.

   4. Enter the following menus: Powertrain / Engine and ECT / Active Test.

   5. According to the display on the GTS, perform the Active Test.

      Tech Tips

      While driving, the shift position can be forcibly changed with the GTS.

      Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem Click here.

      Engine and ECT

      Tester Display	Test Part	Control Range	Diagnostic Note
      Control the Shift Position	Operate shift solenoid valve and set each shift position	Press "→" button: Shift up Press "←" button: Shift down	It is possible to check the operation of the shift solenoid valves. [Vehicle Condition] The vehicle speed is 50 km/h (31 mph) or less.

      Tech Tips

      
      

      • 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-shifts must be performed with the accelerator pedal released.

      • The 6th to 5th and 5th to 4th down-shifts 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 GTS.

      • Gear positions in the event of a solenoid valve mechanical problem:

        Tester gear shift command	1st	2nd	3rd	4th	5th	6th
        Actual gear position under malfunction	1st	1st	3rd	3rd	N*	N*

        N*: Neutral

      OK
      Gear position changes in accordance with the GTS command.

   
   

   NG

   REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Click here

   OK

3. PERFORM ACTIVE TEST USING GTS (SHIFT SOLENOID VALVE SLT)

   Note

   
   

   • Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).

   • Be careful to prevent SST hose from interfering with the exhaust pipe.

   • Perform the test with the A/C turned off.

   Tech Tips

   Using the GTS 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.

   
   
   1. 

      *1

      Test Plug

      Remove the test plug on the transmission case center right side and connect SST.

      SST

      09993-19015   ( 09993-00010, 09993-00040 )

   2. Connect the GTS to the DLC3.

   3. Start the engine and warm it up.

   4. Measure the line pressure with SST.

   5. Turn the GTS on.

   6. Enter the following menus: Powertrain / Engine and ECT / Active Test.

   7. According to the display on the GTS, perform the Active Test.

   8. Measure the line pressure.

      Engine and ECT

      Tester Display	Test Part	Control Range	Diagnostic Note
      Activate the Solenoid (SLT)*	Operate shift solenoid valve SLT and raise line pressure	ON or OFF Tech Tips OFF: Line pressure up (when Active Test "Activate the Solenoid (SLT)" is performed, ECM commands shift solenoid valve SLT to turn OFF) ON: No action (normal operation)	[Vehicle Condition] The vehicle is stopped. The engine is idling.

      Tech Tips

      *: 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 Click here 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 Click here

   OK

4. CLEAR DTC AND PERFORM RUNNING TEST

   
   

   1. Clear the DTC Click here.

   2. Check for DTC again after conducting the Monitor Drive Pattern Click here.

      OK
      No DTC output

   
   

   OK

   END

   NG

   REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Click here