A760E Automatic Transmission
A760E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION 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, Air-flow meter, turbine (input) speed sensor, output 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 a mechanical problems of the shift solenoid valve SLU, valve body and torque converter clutch.
MONITOR DESCRIPTION
Torque converter lock-up is controlled by the ECM based on the turbine (input) speed sensor NT, output speed 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 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 rpm (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 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 the shift solenoid valve SLU or lock-up system performance.
The ECM 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 between 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 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 when the ECM 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 (A)
OFF malfunction (B)
ON malfunction
TYPICAL MALFUNCTION THRESHOLDS
Both of the following condition are met: OFF malfunction (A) and (B)
OFF malfunction (A)
OFF malfunction (B)
ON malfunction (A)
2 detections are necessary per driving cycle:
1st detection; temporary flag ON
2nd detection; pending fault code ON
Vehicle speed must be under 6.2mph (10 km/h) once before 2nd detection.
COMPONENT OPERATING RANGE
INSPECTION PROCEDURE
NOTICE:
Perform the universal trip to clear permanent DTCs A760E Automatic Transmission System.
1. ACTIVE TEST
HINT
Using the Techstream 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.
(a) Warm up the engine.
(b) Turn the engine switch off.
(c) Connect the Techstream to the DLC3.
(d) Turn the engine switch on (IG) position.
(e) Turn the Techstream on.
(f) Select the item "Powertrain / ECT / Active Test".
(g) According to the display on tester, perform the "Active Test".
HINT
- 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.
(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 automatically.)
PROCEDURE
1. CHECK OTHER DTCs OUTPUT (IN ADDITION TO DTC P2757)
(a) Connect the Techstream to the DLC3.
(b) Turn the engine switch on (IG) position and push the Techstream main switch ON.
(c) When you use Techstream:
Select the item "Powertrain / ECT / Trouble Codes".
(d) 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 Transmission System - A760E
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:
Text in Illustration
(c) 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.
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.
NG -- REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.
4. INSPECT TORQUE CONVERTER CLUTCH ASSEMBLY
(a) Check the torque converter clutch assembly A760E Automatic Transmission.
OK:
The torque converter clutch operates normally.
NG -- REPLACE TORQUE CONVERTER CLUTCH ASSEMBLY Removal
OK -- REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Removal