AUTOMATIC TRANSMISSION SYSTEM, Diagnostic DTC:P2757

DESCRIPTION

The TCM uses the signals from the throttle position sensor, air-flow meter, transmission revolution sensor (NT), transmission revolution sensor (SP2) and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

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

MONITOR DESCRIPTION

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

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

The TCM will store the DTC.

CAUTION / NOTICE / HINT

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 / ECT / Active Test.

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

      
      Powertrain > ECT > Active Test

      Tester Display	Measurement Item	Control Range	Diagnostic Note
      Activate the Lock Up	Control shift solenoid valve SLU to set automatic transmission to lock-up	ON or OFF	Possible to check shift solenoid valve SLU operation. [Vehicle Condition] Throttle valve opening angle: Less than 35% Vehicle speed: 80 km/h (50 mph) or more

      
      Powertrain > ECT > Active Test

      Tester Display
      Activate the Lock Up

      Tech Tips

      
      

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

      • This test can be conducted with the 5th gear.

   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 automatically.)

PROCEDURE

1. CHECK DTC 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 / ECT / Trouble Codes.

      
      Powertrain > ECT > Trouble Codes

   5. Read the DTCs using the GTS.

      Result
      Result Proceed to Only P2757 is output A P2757 and other DTCs are output B

      Tech Tips

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

   
   

   B

   GO TO DTC CHART Click here

   A

2. INSPECT SOLENOID(SLU) VALVE

   
   
   1. 

      *a	Component without harness connected (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 2 Battery negative (-) → Terminal 1 Valve moves and makes an operating noise

      Result
      Proceed to OK NG

   
   

   NG

   REPLACE SOLENOID(SLU) VALVE Click here

   OK

3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY

   
   

   1. Check the transmission valve body assembly.

      Click here

      OK
      There are no foreign objects on any valve.

      Result
      Proceed to OK NG

   
   

   NG

   REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Click here

   OK

4. INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY

   
   

   1. Check the torque converter assembly.

      Click here

      OK
      The torque converter assembly operates normally.

      Result
      Proceed to OK NG

   
   

   OK

   REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Click here

   NG

   REPLACE TORQUE CONVERTER ASSEMBLY Click here