AUTOMATIC TRANSMISSION SYSTEM (for 1TR-FE), Diagnostic DTC:P2757

SYSTEM DESCRIPTION

The ECM uses the signals from the throttle position sensor, air-flow meter, input turbine speed sensor, output shaft speed sensor and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

The ECM compares the engagement condition of the lock-up clutch with the lock-up schedule in the ECM memory to detect shift solenoid valve SLU, transmission valve body assembly and torque converter assembly mechanical problems.

MONITOR DESCRIPTION

Torque converter lock-up is controlled by the ECM based on the transmission revolution sensor (NT), transmission revolution sensor (SP2), engine speed, engine load, engine temperature, vehicle speed, transmission fluid temperature and gear selection. The ECM determines the lock-up status of the torque converter by comparing the engine speed (NE) to the input turbine speed (NT). The ECM calculates the actual transmission gear by comparing the input turbine speed (NT) to the output shaft speed (SP2). When conditions are appropriate, the ECM requests "lock-up" by applying control voltage to shift solenoid valve SLU. When shift solenoid valve SLU is turned on, it applies pressure to the lock-up relay valve and locks the torque converter.

If the ECM detects no lock-up after lock-up has been requested or if it detects lock-up when it is not requested, the ECM interprets this as a fault in shift solenoid valve SLU or lock-up system performance.

The ECM will illuminate the MIL and store the DTC.

Example:

When any of the following is met, the system judges it as a malfunction.

• There is a difference in rotation speed between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up.

  (Engine speed is at least 70 rpm more than the input turbine speed.)

• There is no difference in rotation speed between the input side (engine speed) and output side (input turbine speed) of the torque converter when the ECM commands lock-up off.

  (The difference between engine speed and input turbine speed is less than 35 rpm.)

INSPECTION PROCEDURE

1. ACTIVE TEST

   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. Warm up the engine.

   2. Turn the ignition switch off.

   3. Connect the GTS to the DLC3.

   4. Turn the ignition switch to ON.

   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.

      Engine and ECT

      Tester Display	Test Part	Control Range	Diagnostic Note
      Activate the Lock Up	Controls the shift solenoid valves SLU and SL to set the automatic transmission to the lock-up condition.	ON/OFF	Can be used to check shift solenoid valves SLU and SL operation. [Vehicle Condition] Throttle valve opening angle: Less than 30% Vehicle speed: 80 km/h (50 mph) or more

      Tech Tips

      
      

      • This test can be conducted when the vehicle speed is 80 km/h (50 mph) or more.

   8. Lightly depress the accelerator pedal and check that the engine speed does not change abruptly.

      Tech Tips

      
      

      • When changing the accelerator pedal opening angle while driving, if the engine speed does not change, lock-up is on.

      • Slowly release the accelerator pedal in order to decelerate, but do not fully release the pedal. (Fully releasing the pedal will close the throttle valve and lock-up may be turned off.)

      

PROCEDURE

1. CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P2757)

   
   

   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 DTC P2757 is output	A
      P2757 and other DTCs are output	B

      Tech Tips

      If any DTCs other than P2757 are output, perform troubleshooting for those DTCs first.

   
   

   B

   GO TO DTC CHART Click here

   A

2. INSPECT SHIFT SOLENOID VALVE SLU

   
   
   1. 

      Text in Illustration

      *1	Shift Solenoid Valve SLU

      Remove shift solenoid valve SLU Click here.

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

      Standard Resistance
      Tester Connection Condition Specified Condition 1 - 2 20°C (68°F) 5.0 to 5.6 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 (+) with a 21 W bulb → Terminal 1 Battery negative (-) → Terminal 2 Valve moves and makes an operating noise

   
   

   NG

   REPLACE SHIFT SOLENOID VALVE SLU Click here

   OK

3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY

   
   

   1. Check the transmission valve body assembly Click here.

      OK
      There is no foreign matter on each valve and they operate smoothly.

   
   

   NG

   REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Click here

   OK

4. INSPECT TORQUE CONVERTER ASSEMBLY

   
   

   1. Check the torque converter assembly Click here.

      OK
      The torque converter assembly operates normally.

   
   

   NG

   REPLACE TORQUE CONVERTER ASSEMBLY Click here

   OK

   REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Click here