P2757
U341E 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)
SYSTEM 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.
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.
MONITOR DESCRIPTION
Torque converter lock-up is controlled by the ECM based on the speed sensor (NT), engine rpm (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 rpm (NE) to the input turbine rpm (NT). The ECM calculates the actual transmission gear by comparing input turbine rpm (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 clutch.
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.
* 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.)
* 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
TYPICAL ENABLING CONDITIONS
The following conditions are common to OFF malfunction and ON malfunction.
OFF malfunction:
OFF malfunction::
ON malfunction:
ON malfunction::
TYPICAL MALFUNCTION THRESHOLDS
OFF malfunction:
OFF malfunction::
[ON malfunction]
* 2 detections are necessary per driving cycle.
* 1st detection: Temporary flag ON
* 2nd detection: Pending fault code ON
* Vehicle speed must be under 6.2 mph (10 km/h) once before 2nd detection.
ON malfunction:
ON malfunction::
INSPECTION PROCEDURE
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.
1. PERFORM ACTIVE TEST
(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 on the Techstream.
(f) Select the item: "Powertrain / Engine and ECT / Active Test".
(g) According to the display on the Techstream, perform the Active Test.
HINT
- This test can be conducted when the vehicle speed is 60 km/h (36 mph) or more.
- This test can be conducted in the 4th gear.
(h) Lightly depress the accelerator pedal and check that the engine speed does not change abruptly.
HINT
- 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)
(a) Connect the Techstream to the DLC3.
(b) Turn the ignition switch to ON and the Techstream main switch on.
(c) Select the item: "Powertrain / Engine and ECT / Trouble Codes".
(d) Read the DTCs using the Techstream.
Result:
HINT
If any other codes besides "P2757" are output, perform the troubleshooting for those DTCs first.
B -- GO TO DTC CHART Diagnostic Trouble Code Descriptions
A -- Continue to next step.
2. INSPECT SHIFT SOLENOID VALVE SLU
(a) Remove the shift solenoid valve SLU.
(b) Measure the resistance according to the value(s) in the table below.
Standard resistance:
(c) Connect the positive (+) lead with a 21 W bulb to terminal 2 and negative (-) lead to terminal 1 of the solenoid valve connector, then check the movement of the valve.
OK:
The solenoid makes an operating sound.
NG -- REPLACE SHIFT SOLENOID VALVE SLU Disassembly
OK -- Continue to next step.
3. INSPECT TRANSMISSION VALVE BODY ASSEMBLY
OK:
There are no foreign objects on each valve and they operate smoothly.
NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.
4. INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY
OK:
The torque converter clutch operates normally.
NG -- REPLACE TORQUE CONVERTER CLUTCH ASSEMBLY Removal
OK -- REPAIR OR REPLACE AUTOMATIC TRANSAXLE ASSEMBLY Removal