P0746
A750E AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: P0746, P0771: Pressure Control Solenoid "A" Performance (Shift Solenoid Valve SL1)
DESCRIPTION
The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th or 5th gear).
Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake, gear, etc.).
MONITOR DESCRIPTION
These DTCs indicate a stuck ON malfunction or stuck OFF malfunction of the shift solenoid valves SR and SL1.
The ECM commands gear shifts by turning the shift solenoid valves ON/OFF. When the gear position commanded by the ECM and the actual gear position are not the same, the ECM illuminates the MIL and stores the DTC.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
All
P0746 and P0771: OFF Malfunction (A)
P0746 and P0771: OFF Malfunction (B)
P0746 and P0771: OFF Malfunction (C)
P0771: ON Malfunction
TYPICAL MALFUNCTION THRESHOLDS
[P0746 and P0771: OFF malfunction]
- All of the following conditions are met: OFF malfunction (A), (B) and (C)
- 2 detections are necessary per driving cycle
- 1st detection: temporary flag ON
- 2nd detection: pending fault code ON
OFF Malfunction (A)
OFF Malfunction (B)
OFF Malfunction (C)
[P0771: ON malfunction]
- 2 detections are necessary per driving cycle
- 1st detection: temporary flag ON
- 2nd detection: pending fault code ON
ON Malfunction
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 / Engine and ECT / Active Test.
(g) According to the display on the Techstream, perform the Active Test.
HINT
While driving, the shift position can be forcibly changed with the Techstream.
Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem Fail-Safe Chart.
Engine and ECT
HINT
* This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
* The 4th to 5th up-shift must be performed with the accelerator pedal released.
* The 5th to 4th down-shift must be performed with the accelerator pedal released.
* Do not operate the accelerator pedal for at least 2 seconds after shifting and do not shift successively.
* The shift position commanded by the ECM is shown in the Data List display on the Techstream.
* The shift solenoid valves SL1 and SR turn ON/OFF normally when the shift lever is in D.
PROCEDURE
1. CHECK DTC OUTPUT (IN ADDITION TO DTCS P0746 AND P0771)
(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 / Engine and ECT / Trouble Codes.
(e) Read the DTCs using the Techstream.
Result
HINT
If any other codes besides P0746 and P0771 are output, perform troubleshooting for those DTCs first.
B -- GO TO DTC CHART Automatic Transmission System - A750E
A -- Continue to next step.
2. PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT)
NOTICE:
* Perform the test while the ATF temperature is 50 to 80°C (122 to 176°F).
* Be careful to prevent SST's hose from interfering with the exhaust pipe.
* Perform the test with the A/C off.
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) Remove the test plug from the transmission case and connect SST.
SST : 09992-00095
09992-00231
09992-00271
(b) Connect the Techstream to the DLC3.
(c) Start the engine and warm it up.
(d) Measure the line pressure with SST.
(e) Turn the Techstream on.
(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.
(g) According to the display on the Techstream, perform the Active Test.
(h) Measure the line pressure.
Engine and ECT
HINT
*: Activate the Solenoid (SLT) in the Active Test is performed to check the line pressure changes by connecting SST to the automatic transmission, which is used in the Hydraulic Test Hydraulic Test as well. Note that the pressure values in the Active Test and Hydraulic Test are different.
OK:
The line pressure changes as specified when performing the Active Test.
NG -- REPLACE SHIFT SOLENOID VALVE SLT Disassembly
OK -- Continue to next step.
3. INSPECT SHIFT SOLENOID VALVE SL1
(a) Remove shift solenoid valve SL1.
(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 SL1 Disassembly
OK -- Continue to next step.
4. INSPECT SHIFT SOLENOID VALVE SR
(a) Remove shift solenoid valve SR.
(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 SR Disassembly
OK -- Continue to next step.
5. INSPECT TRANSMISSION VALVE BODY ASSEMBLY
(a) Check the transmission valve body assembly Disassembly.
OK:
There are no foreign objects on any valve.
NG -- REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Removal