P2757

U760E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSAXLE SYSTEM: P2757: Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU)
P2757 - Torque Converter Clutch Pressure Control Solenoid Performance (Shift Solenoid Valve SLU)

DESCRIPTION

The TCM uses the signals from the throttle position sensor, air flow meter, input turbine 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 mechanical problems.









MONITOR DESCRIPTION

Torque converter lock-up is controlled by the TCM based on the input turbine speed sensor (speed sensor NT), output speed sensor (speed sensor NC), engine speed, engine load, engine temperature, vehicle speed, ATF 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 the input turbine speed (NT) to the output shaft speed (NC). When conditions are appropriate, the TCM 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 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 either of the following is met, the system judges it to be a malfunction.

- There is a difference in 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 more than input turbine speed.)

- There is no difference in 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 20 rpm.)

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

The following items are common to all conditions below.





OFF malfunction





TYPICAL MALFUNCTION THRESHOLDS

OFF malfunction





COMPONENT OPERATING RANGE





INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

1. 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.

(a) Warm up the engine.

(b) Turn the ignition switch off.

(c) Connect the Techstream to the DLC3.

(d) Turn the ignition switch to ON.

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / ECT / Active Test.

(g) According to the display on the Techstream, perform the Active Test.

ECT





(h) Lightly depress the accelerator pedal and check that the engine speed does not change abruptly.

HINT
- When depressing the accelerator pedal while driving, if the engine speed does not change abruptly, lock-up is on.
- When decelerating, slowly release the accelerator pedal, but do not fully release it (fully releasing the pedal will close the throttle valve and lock-up may be turned off).





PROCEDURE

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

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / ECT / Trouble Codes.

(e) Read the DTCs using the Techstream.

Result





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

B -- GO TO DTC CHART Automatic Transaxle System - U760E
A -- Continue to next step.

2. INSPECT SHIFT SOLENOID VALVE SLU

(a) Remove shift solenoid valve SLU.





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

Standard Resistance:





(c) Apply 12 V battery voltage to the shift solenoid valve and check that the valve moves and makes an operating noise.

OK:





Text in Illustration





NG -- REPLACE SHIFT SOLENOID VALVE SLU Disassembly
OK -- Continue to next step.

3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY P0741

NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.

4. INSPECT TORQUE CONVERTER ASSEMBLY P0741

NG -- REPLACE TORQUE CONVERTER ASSEMBLY Removal

OK -- REPAIR OR REPLACE AUTOMATIC TRANSAXLE ASSEMBLY Removal