DTC    P2757    Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU)


DESCRIPTION

The ECM uses the signals from the throttle position sensor, turbine (input) speed sensor, vehicle speed sensor and crankshaft position sensor to monitor the engagement condition of the lock-up clutch.

C233511E01

Then 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 shift solenoid valve SLU, valve body and torque converter clutch.

DTC No.
DTC Detection Condition
Trouble Area
P2757
Lock-up does not occur when driving in lock-up range or lock-up remains ON in lock-up OFF range (2 trip detection logic).
  1. Shift solenoid valve SLU remains open or closed
  2. Valve body is blocked
  3. Shift solenoid valve SLU
  4. Torque converter assembly
  5. Automatic transaxle (clutch, brake or gear etc.)
  6. Line pressure is too low

MONITOR DESCRIPTION

Torque converter lock-up is controlled by the ECM based on the input turbine speed (NT), engine speed (NE), engine load, engine coolant 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 rpm (NT). The ECM calculates the actual transmission gear by comparing input turbine speed (NT) to output shaft speed. When conditions are appropriate, the ECM requests lock-up by applying the control voltage to shift solenoid valve SLU. When 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 turns on the MIL and stores the DTC.
Example:
When either of the following is met, the system judges it as a malfunction.
  1. There is a difference in the rotations of 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 100 rpm greater than input turbine speed.)
  2. There is no difference in the rotations of 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.)

MONITOR STRATEGY


Related DTCs
P2757:
Shift solenoid valve SLU/OFF malfunction
Shift solenoid valve SLU/ON malfunction
Required sensors/Components
Shift solenoid valve SLU, Speed sensor (NT), Crankshaft position sensor (NE)
Frequency of operation
Continuous
Duration
OFF malfunction: 3.5 seconds
ON malfunction: 1.8 seconds
MIL operation
2 driving cycles
Sequence of operation
None

TYPICAL ENABLING CONDITIONS

The following conditions are common to OFF malfunction and ON malfunction.

Time after shifting N to D
4.5 seconds or more
ECT (Engine Coolant Temperature)
60°C (140°F) or more
Transmission shift position
D
ECM selected gear
3rd or 4th
Vehicle speed
25 km/h (15.5 mph) or more
Shift Solenoid "A" (S1) circuit
No circuit malfunction
(P0973, P0974)
Shift Solenoid "B" (S2) circuit
No circuit malfunction
(P0976, P0977)
Torque Converter Clutch Pressure Control Solenoid (SLU) circuit
No circuit malfunction
(P2759)
ECT sensor circuit
No circuit malfunction
(P0115, P0117, P0118)
Turbine Speed Sensor circuit
No circuit malfunction
(P0717)
Vehicle Speed Sensor "A" circuit
No circuit malfunction
(P0500)
Electronic Throttle Control System
No circuit malfunction
(P0120, P0121, P0122, P0123, P0220, P0222, P0223, P0604, P0606, P0607, P060A, P060B, P060D, P060E, P0657, P1607, P2102, P2103, P2111, P2112, P2118, P2119, P2135)

OFF malfunction: 
ECM lock-up command
ON (SLU: 100%)
Input speed/Output speed (NT/NO)
NT: Input (Turbine) speed
NO: Output speed
0.64 to 0.78
or
0.95 to 1.09
Input speed/Output speed (NT/NO) at ECM selected 2nd gear
0.64 to 0.78
or
0.95 to 1.09
or
1.50 to 1.80
Duration time from lock-up on command
3 seconds or more

ON malfunction: 
ECM lock-up command
OFF (SLU: 10%)
Input speed/Output speed (NT/NO)
0.95 to 1.09
Throttle valve opening angle
8% or more
Vehicle speed
Less than 60 km/h (37.3 mph)
Calculated load value
22% or more

TYPICAL MALFUNCTION THRESHOLDS


OFF malfunction: 
Engine speed - Input (turbine) speed (NE - NT)
100 rpm or more
[ON malfunction]
  1. 2 detections are necessary per driving cycle.
    1st detection: Temporary flag ON
    2nd detection: Pending fault code ON
    Vehicle speed must be under 10 km/h (6.2 mph) once before 2nd detection.

ON malfunction: 
Difference between engine speed and Input (turbine) speed
Less than 35 rpm

INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs (Click here).

ACTIVE TEST

HINT:
Using the Techstream 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.
It is possible to display the Data List during the Active Test.
  1. Warm up the engine.

  2. Turn the ignition switch off.

  3. Connect the Techstream to the DLC3.

  4. Turn the ignition switch to ON.

  5. Turn the Techstream on.

  6. Enter the following menus: Powertrain / Engine and 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
    [Test Details]
    Control shift solenoid SLU to set automatic transaxle to lock-up condition.
    ON/OFF
    Possible to check Lock-up operation.
    [Vehicle Condition]
    Vehicle speed: 60 km/h (36 mph) or more, and 4th gear

    HINT:
    1. This test can be conducted when the vehicle speed is 60 km/h (36 mph) or less.
    2. This test can be conducted in 4th gear.


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


    G029214E05

    HINT:
    1. When changing the accelerator pedal opening angle while driving, if the engine speed does not change, lock-up is on.
    2. Slowly, but not fully, release the accelerator pedal in order to decelerate. (Fully releasing the pedal will close the throttle valve and lock-up may be turned off.)
1.CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P2757)
  1. Connect the Techstream to the DLC3.

  1. Turn the ignition switch to ON.

  1. Turn the Techstream on.

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

  1. Read the DTCs using the Techstream.

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

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


B
GO TO DTC CHART (Click here)
A


2.INSPECT SHIFT SOLENOID VALVE SLU
C204845E05
  1. Remove shift solenoid valve SLU.

  1. 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
  1. 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 operating sounds.
    Text in Illustration 
    *a
    Component without harness connected
    (Shift Solenoid Valve SLU)


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 any valves 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 operates normally.


NG
REPLACE TORQUE CONVERTER ASSEMBLY (Click here)
OK

REPLACE AUTOMATIC TRANSAXLE ASSEMBLY (Click here)