AUTOMATIC TRANSAXLE SYSTEM, Diagnostic DTC:P2757

SYSTEM DESCRIPTION

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

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

MONITOR DESCRIPTION

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

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 lock-up system performance.

The TCM will turn on 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 TCM commands lock-up.

  (Engine speed is at least 70 rpm greater than 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 TCM commands lock-up off.

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

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

COMPONENT OPERATING RANGE

INSPECTION PROCEDURE

1. ACTIVE TEST

   1. Warm up the engine.

   2. Turn the engine switch off.

   3. Connect the Techstream to the DLC3.

   4. Turn the engine switch on (IG).

   5. Turn the Techstream on.

   6. Enter the following menus: Powertrain / ECT / Active Test.

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

      Tester Display	Test Part	Control Range	Diagnostic Note
      Activate the Lock Up	Control the shift solenoid SLU and SL to set the automatic transaxle to the lock-up condition.	ON/OFF	Can be used to check SLU and SL solenoid operation. [Vehicle Condition] Throttle valve opening angle: Less than 20% Vehicle speed:60 km/h (37 mph) or more, and 6th gear

      Tech Tips

      • This test can be conducted when the vehicle speed is 60 km/h (37 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, 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.)

      

PROCEDURE

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

   1. Connect the Techstream to the DLC3.

   2. Turn the engine switch on (IG).

   3. Turn the Techstream on.

   4. Enter the following menus: Powertrain / ECT / Trouble Codes.

   5. Read the DTCs using the Techstream.

      Result
      Display (DTC output) 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 SHIFT SOLENOID VALVE SLU

   1. Remove 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

      Text in Illustration

      *1	Shift Solenoid Valve SLU

   3. Connect a battery positive (+) lead with a 21 W bulb to terminal 2 and a negative (-) lead to terminal 1 of the solenoid valve connector. Then check that the valve moves and makes an operating sound.

      OK
      Valve moves and makes an operating sound.

   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 are no foreign objects on each valve and they operate smoothly.

   NG

   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 clutch operates normally.

   NG

   REPLACE TORQUE CONVERTER ASSEMBLY Click here

   OK

   REPLACE AUTOMATIC TRANSAXLE ASSEMBLY Click here