AUTOMATIC TRANSMISSION SYSTEM, Diagnostic DTC:P2757

SYSTEM DESCRIPTION

The ECM 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.

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

MONITOR DESCRIPTION

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

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 malfunction of in the shift solenoid valve SLU or lock-up system performance.

The ECM will illuminate the MIL and store this DTC.

Example:

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

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

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

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

  (The difference between engine speed and input turbine speed is less than 20 rpm.)

CAUTION / NOTICE / HINT

1. ACTIVE TEST

   Tech Tips

   Using the GTS to perform Active Test 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. 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 / Activate the Lock Up.

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

      
      Powertrain > Engine > 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] Vehicle speed: 60 km/h (36 mph) or more

      
      Powertrain > Engine > Active Test

      Tester Display
      Activate the Lock Up

      Tech Tips

      
      

      • This test can be conducted when the vehicle speed is 58 km/h (36 mph) or more.

      • This test can be conducted with the 5th or 6th 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, but not fully, the accelerator pedal in order to decelerate. (Fully releasing the pedal will close the throttle valve and lock-up may be turned off automatically.)

PROCEDURE

1. CHECK OTHER DTCS OUTPUT

   
   

   1. Connect the GTS to the DLC3.

   2. Turn the engine switch on (IG).

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

      
      Powertrain > Engine > Trouble Codes

   4. 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. 

      *a	Shift Solenoid Valve SLU

      Remove the shift solenoid valve SLU.

   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. Connect the positive (+) lead with a 21 W bulb to terminal 2 and the negative (-) lead to terminal 1 of the solenoid valve connector, then check the movement of the valve.

      OK
      The solenoid makes an operating sound.

      Result
      Proceed to OK NG

   
   

   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.

      Result
      Proceed to OK NG

   
   

   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.

      Result
      Proceed to OK NG

   
   

   OK

   REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Click here

   NG

   REPLACE TORQUE CONVERTER ASSEMBLY Click here