DESCRIPTION
The TCM uses signals from the transmission revolution sensor (NT) and transmission revolution sensor (SP2) to detect the actual gear position (1st, 2nd, 3rd, 4th or 5th gear).
Then the TCM compares the actual gear with the shift schedule in the TCM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake, gear, etc.).
| DTC No. | Detection Item | DTC Detection Condition | Trouble Area | MIL | Memory |
|---|---|---|---|---|---|
| P0756 | Shift Solenoid "B" Performance (Shift Solenoid Valve S2) | Gear required by the TCM does not match the actual gear when driving (1-trip detection logic). |
|
- | DTC stored |
MONITOR DESCRIPTION
This DTC indicates a stuck ON malfunction or stuck OFF malfunction of shift solenoid valve S2.
The TCM commands gear shifts by turning the shift solenoid valves ON/OFF. When the gear position commanded by the TCM and the actual gear position are not the same, the TCM stores the DTC.
CAUTION / NOTICE / HINT
Note
Perform registration and/or initialization when parts related to the automatic transmission are replaced.
Tech Tips
After the repair, clear the DTCs and perform the following procedure to check that DTCs are not output.
Perform the D Position Shift Test in Road Test.
Check for DTCs again.
ACTIVE TEST
Tech Tips
Using the GTS 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.
Warm up the engine.
Turn the ignition switch off.
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / ECT / Active Test.
According to the display on the GTS, perform the Active Test.
Tech Tips
While driving, the shift position can be forcibly changed with the GTS.
Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem.
| Tester Display | Measurement Item | Control Range | Diagnostic Note |
|---|---|---|---|
| Control the Shift Position | Operate shift solenoid valves and set each shift position |
|
Possible to check operation of the shift solenoid valves. [Vehicle Condition] 50 km/h (31 mph) or less |
| Active Test Display |
|---|
| Control the Shift Position |
| Data List Display |
|---|
| Shift Status |
Tech Tips
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 TCM is shown in the Data List display on the GTS.
Shift solenoid valve S2 is turned ON/OFF normally when the shift lever is in D.
| TCM gear shift command | 1st | 2nd | 3rd | 4th | 5th |
| Shift solenoid valve S2 | OFF | ON | ON | OFF | OFF |
PROCEDURE
CHECK DTC OUTPUT (IN ADDITION TO DTC P0756)
Connect the GTS to the DLC3.
Turn the ignition switch to ON.
Turn the GTS on.
Enter the following menus: Powertrain / ECT / Trouble Codes.
Read the DTCs using the GTS.
| Result | ||||||
|---|---|---|---|---|---|---|
|
Tech Tips
If any other codes besides P0756 are output, perform troubleshooting for those DTCs first.
| B |
|
GO TO DTC CHART Click here |
| A |
|
PERFORM ACTIVE TEST USING GTS (SHIFT SOLENOID VALVE SLT)
Note
Perform the test while the ATF temperature is between 50 and 80°C (122 and 176°F).
Be careful to prevent the hose of SST from interfering with the exhaust pipe.
Perform the test with the air conditioning off.
Tech Tips
Using the GTS 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.
Remove the test plug from the transmission case and connect SST.
Connect the GTS to the DLC3.
Start the engine and warm it up.
Measure the line pressure with SST.
Turn the GTS on.
Enter the following menus: Powertrain / ECT / Active Test.
According to the display on the GTS, perform the Active Test.
Measure the line pressure.
| Tester Display | Measurement Item | Control Range | Diagnostic Note |
|---|---|---|---|
| Activate the Solenoid (SLT) | Operate shift solenoid valve SLT and raise line pressure | ON or OFF Tech Tips
|
[Vehicle Condition]
|
| Tester Display |
|---|
| Activate the Solenoid (SLT) |
The "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 as well.
Tech Tips
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. |
| Result | |||
|---|---|---|---|
|
| NG |
|
REPLACE SHIFT SOLENOID VALVE S2 Click here |
| OK |
|
INSPECT SHIFT SOLENOID VALVE S2
| *a | Component without harness connected (Shift Solenoid Valve S2) |
Remove shift solenoid valve S2.
Measure the resistance according to the value(s) in the table below.
| Standard Resistance | ||||||
|---|---|---|---|---|---|---|
|
Apply 12 V battery voltage to the shift solenoid valve and check that the valve moves and makes an operating noise.
| OK | ||||
|---|---|---|---|---|
|
| Result | |||
|---|---|---|---|
|
| NG |
|
REPLACE SHIFT SOLENOID VALVE S2 Click here |
| OK |
|
INSPECT TRANSMISSION VALVE BODY ASSEMBLY
Check the transmission valve body assembly.
| OK |
|---|
| There are no foreign objects on any valve. |
| Result | |||
|---|---|---|---|
|
| OK |
|
REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY Click here |
| NG |
|
REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY Click here |