Dtc P0781 1-2 Shift (1-2 Shift Valve)

DESCRIPTION

MONITOR DESCRIPTION

INSPECTION PROCEDURE

CHECK DTC OUTPUT (IN ADDITION TO DTC P0781)

PERFORM ACTIVE TEST USING GTS (RUNNING TEST)

PERFORM ACTIVE TEST USING GTS (SHIFT SOLENOID VALVE SLT)

CLEAR DTC AND PERFORM RUNNING TEST

DESCRIPTION

1. 
   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 gearshift to switch to 5th and 6th gear and the engine overruns (clutch slips), this DTC is output.
   
   

   DTC Code	DTC Detection Condition	Trouble Area
   P0781	When conditions (a) and (b), or (a) and (c) are met. (2 trip detection logic*1, 1 trip detection logic*2) (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, gear, etc.)

   1. *1: w/ OBD
      
   2. *2: w/o OBD
      
   
   

   HINT:

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

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

      N*: Neutral
      
   2. 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

INSPECTION PROCEDURE

1. Connect the GTS to the DLC3.
   

2. Turn the engine switch on (IG).
   

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

   HINT:

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

CAUTION:

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

NOTICE:

1. Perform the test while the ATF temperature is between 50 and 80°C (122 and 176°F).
   
2. Perform the test with the A/C turned off.
   

HINT:

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 Test early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Test.

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.
   

   HINT:

   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 valves and set each shift position by yourself	Press "→" button: Shift up Press "←" button: Shift down	Possible to check operation of the shift solenoid valves. [Vehicle Condition] 50 km/h (30 mph) or less

   HINT:

   1. This test can be conducted when the vehicle speed is 50 km/h (30 mph) or less.
      
   2. The 4th to 5th and 5th to 6th up-shift must be performed with the accelerator pedal released.
      
   3. The 6th to 5th and 5th to 4th down-shift must be performed with the accelerator pedal released.
      
   4. Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
      
   5. The shift position commanded by the ECM is shown in the Data List display on the GTS.
      
   6. Gear positions in the event of a solenoid valve mechanical problem:
      
      

      Tester command gearshift	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.
      

NOTICE:

1. Perform the test while the ATF temperature is between 50 and 80°C (122 and 176°F).
   
2. Be careful to prevent the hose of SST from interfering with the exhaust pipe.
   
3. Perform the test with the A/C off.
   

HINT:

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. Remove the test plug on the transmission case and connect SST.
   

SST

09992-00095(09992-00231,09992-00271)

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 the shift solenoid SLT and raise line pressure	ON or OFF HINT: OFF: Line pressure up (when Active Test "Activate the Solenoid (SLT)" is performed, ECM commands SLT solenoid to turn OFF) ON: No action (normal operation)	[Vehicle Condition] Vehicle stopped Engine idling

   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 (Click here) 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.
   

1. Clear the DTC (Click here).
   

2. Check for DTCs again after conducting the Monitor Drive Pattern (Click here).
   

   OK:

   No DTC code output.