Lexus IS250 IS220d GSE20 ALE20 - A960E AUTOMATIC TRANSMISSION
CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0766)
PERFORM ACTIVE TEST BY INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT)
INSPECT SHIFT SOLENOID VALVE S4
INSPECT SHIFT SOLENOID VALVE SL2
INSPECT TRANSMISSION VALVE BODY ASSEMBLY
DTC P0766 Shift Solenoid "D" Performance (Shift Solenoid Valve S4)
SYSTEM 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, 5th or 6th 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 or gear, etc.).
| DTC No. | DTC Detection Condition | Trouble Area |
| P0766 | "S4 stuck OFF malfunction", "SL2 stuck ON malfunction" or "Brake control valve malfunction"*1: Shifting to 5th and 6th gears is impossible. The ECM determines there is a malfunction when the following conditions are both met.(2-trip detection logic) When the ECM directs the gearshift to switch to 5th gear, the actual gear is shifted to 4th. When the ECM directs the gearshift to switch to 6th gear, the actual gear is shifted to 4th. |
Shift solenoid valve S4 remains closed Shift solenoid valve SL2 remains open Shift solenoid valve SLT remains open or closed Valve body is blocked (Brake control valve) Automatic transmission (clutch, brake or gear, etc.) |
- HINT:
| ECM command gearshift | 1st | 2nd | 3rd | 4th | 5th | 6th |
| *1: Actual gear position under malfunction | ↑ | ↑ | ↑ | ↑ | 4th | 4th |
If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown in the table below.
| Gear position under normal conditions | 1st | 2nd | 3rd | 4th | 5th | 6th |
| *1: Actual gear position under fail-safe mode | ↑ | ↑ | ↑ | 3rd | 3rd | 3rd |
MONITOR DESCRIPTION
This DTC indicates "stuck OFF malfunction" of the shift solenoid valve S4, "stuck ON malfunction" of the shift solenoid valve SL2, or brake control valve malfunction. 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 same, the ECM illuminates the MIL and stores the DTC.
INSPECTION PROCEDURE
| ACTIVE TEST |
- HINT:
- Performing the intelligent tester Active Test allows relay, Vacuum Switching Valve (VSV), actuator and other items to be operated without removing any parts. Performing the Active Test early in troubleshooting is one way to shorten labor time.
- The Data List can be displayed during the Active Test.
Warm up the engine.
Turn the engine switch off.
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) position.
Turn on the tester.
Select the item "Enter / Powertrain / ECT / Active Test".
Follow the instructions on the tester and read the Active Test.
- HINT:
- While driving, the shift position can be forcibly changed with the intelligent tester.
- Comparing the shift position commanded by the ACTIVE TEST with the actual shift position enables you to confirm the problem .
| Item | Test Details | Diagnostic Note |
| Control Shift Position | [Test Details] Operate the shift solenoid valve and set each shift position by yourself. [Vehicle Condition] IDL: ON (4th, 5th and 6th) Less than 50 km/h (31 mph) Press "→" button: Shift up Press "←" button: Shift down |
Possible to check the operation of the shift solenoid valves. |
- HINT:
| ECM command gearshift | 1st | 2nd | 3rd | 4th | 5th | 6th |
| Shift solenoid valve S4 | OFF | ON | ON | ON | ON | ON |
| Shift solenoid valve SL2 | ON | ON | ON | ON | OFF | OFF |
| 1.CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0766) |
Connect the intelligent tester to the DLC3.
Turn the engine switch on (IG) position.
Turn on the tester
Select the item "Powertrain / ECT / DTC / Current or Pending".
Read the DTCs using the intelligent tester.
- Result:
Display (DTC output) Proceed to Only "P0766" is output A "P0766" and other DTCs B
- HINT:
- If any other codes besides "P0766" are output, perform troubleshooting for those DTCs first.
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| A | |
| 2.PERFORM ACTIVE TEST BY INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT) |
- NOTICE:
- HINT:
- Performing the intelligent tester Active Test allows relay, Vacuum Switching Valve (VSV), actuator and other items to be operated without removing any parts. Performing the Active Test early in troubleshooting is one way to shorten labor time.
- The Data List can be displayed during the Active Test.
Turn the engine switch off.
Lift the vehicle up.
Remove the test plug on the transmission case center right side and connect SST.
- SST
- 09992-00095(09992-00231,09992-00271)
Lower the vehicle.
Fully apply the parking brake and chock the 4 wheels.
Connect the intelligent tester to the DLC3.
Start the engine.
Warm up the ATF (Automatic Transmission Fluid).
Measure the line pressure when the engine is idling.
Turn on the intelligent tester.
Select the item "Enter / Powertrain / ECT / Active Test".
Follow the instructions on the tester and perform the Active Test.
Measure the line pressure with SST.
| Item | Test Details |
| Activate the Solenoid (SLT)* | [Test Details] Operate the shift solenoid SLT and raise the line pressure. [Vehicle Condition] Vehicle Stopped. IDL: ON
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*: "Activate the Solenoid (SLT)" in the ACTIVE TEST is performed to check the line pressure changes by connecting the SST to the automatic transmission, which is used in the HYDRAULIC TEST as well.
- HINT:
- The pressure values in ACTIVE TEST and HYDRAULIC TEST are different from each other.
- OK:
- The line pressure changes as specified when performing the ACTIVE TEST.
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| OK | |
| 3.INSPECT SHIFT SOLENOID VALVE S4 |
Remove the shift solenoid valve S4.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Specified Condition
20°C (68°F)Solenoid Connector (S4) - Solenoid Body (S4) 11 to 15 Ω
Connect the positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.
- OK:
- The solenoid makes an operating sound.
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| OK | |
| 4.INSPECT SHIFT SOLENOID VALVE SL2 |
Remove the shift solenoid valve SL2.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Specified Condition
20°C (68°F)1 - 2 5.0 to 5.6 Ω
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.
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| OK | |
| 5.INSPECT TRANSMISSION VALVE BODY ASSEMBLY |
- OK:
- There are no foreign objects on each valve.
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| OK | ||
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