AUTOMATIC TRANSMISSION SYSTEM (for 1UR-FE), Diagnostic DTC:P0751

DESCRIPTION

The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).

Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake, gear, etc.).

• *3: w/ OBD

• *4: w/o OBD

MONITOR DESCRIPTION

This DTC indicates a stuck ON malfunction or stuck OFF malfunction of shift solenoid valve S1.

The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF". When the gear position commanded by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and stores the DTC.

INSPECTION PROCEDURE

1. ACTIVE TEST

   Tip:

   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. Warm up the engine.

   2. Turn the engine switch off.

   3. Connect the GTS to the DLC3.

   4. Turn the engine switch on (IG).

   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.

      Tip:

      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).

      Table 1. 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

      Tip:
      

      • This test can be conducted when the vehicle speed is 50 km/h (30 mph) or less.

      • The 4th to 5th and 5th to 6th up-shift must be performed with the accelerator pedal released.

      • The 6th to 5th and 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 GTS.

      • Shift solenoid valve S1 turns ON/OFF normally when the shift lever is in D.

        ECM command gearshift	1st	2nd	3rd	4th	5th	6th
        Shift solenoid valve S1	OFF	ON	ON	ON	ON	ON

PROCEDURE

1. Click here

   CHECK DTC OUTPUT (IN ADDITION TO DTC P0751)

   
   

   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.

      Table 2. Result

      Result	Proceed to
      Only P0751 is output	A
      P0751 and other DTCs are output	B

      Tip:

      If any other codes besides P0751 are output, perform troubleshooting for those DTCs first.

   
   
   • AClick here
   • BClick here
2. Click here

   PERFORM ACTIVE TEST USING GTS (SHIFT SOLENOID VALVE SLT)

   Note:
   

   • Perform the test while the ATF temperature is between 50 and 80°C (122 and 176°F).

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

   • Perform the test with the A/C off.

   Tip:

   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.

      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.

      Table 3. 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 Tip: 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

      Tip:

      *: 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.

   
   
   • OKClick here
   • NGClick here
3. Click here

   INSPECT SHIFT SOLENOID VALVE S1

   
   
   1. 

      Remove the shift solenoid valve S1.

   2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition Shift solenoid valve S1 connector terminal - Shift solenoid valve S1 body 20°C (68°F) 11 to 15 Ω

   3. Apply 12 V battery voltage to the shift solenoid valve and check that the valve moves and makes an operating noise.

      OK
      Measurement Condition Specified Condition Battery positive (+) → Shift solenoid valve S1 connector Battery negative (-) → Shift solenoid valve S1 body Valve moves and makes an operating noise

      Table 4. Text in Illustration

      *a	Component without harness connected (Shift Solenoid Valve S1)

   
   
   • OKClick here
   • NGClick here
4. Click here

   INSPECT TRANSMISSION VALVE BODY ASSEMBLY

   
   

   1. Check the transmission valve body assembly (Click here).

      OK
      There are no foreign objects on each valve.

   
   
   • OKClick here
   • NGClick here
5. Click here

   REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLYClick here

6. Click here

   GO TO DTC CHARTClick here

7. Click here

   REPLACE SHIFT SOLENOID VALVE SLTClick here

8. Click here

   REPLACE SHIFT SOLENOID VALVE S1Click here

9. Click here

   REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLYClick here