Lexus IS250 IS220d GSE20 ALE20 - A960E AUTOMATIC TRANSMISSION
CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0729)
PERFORM ACTIVE TEST BY INTELLIGENT TESTER
PERFORM ACTIVE TEST BY INTELLIGENT TESTER (SHIFT SOLENOID VALVE SLT)
CLEAR THE DTC AND RUNNING TEST
DTC P0729 Gear 6 Incorrect Ratio
SYSTEM DESCRIPTION
The ECM uses signals from the output speed sensor SP2 and input speed sensor NT 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 Detecting Condition | Trouble Area |
| P0729 | 6th gearshift malfunction: The ECM determines there is a malfunction when both of the following conditions are met. (2-trip detection logic) When the ECM directs the gearshift to switch to 5th gear, the actual gear is also shifted to 5th. When the ECM directs the gearshift to switch to 6th gear, the actual gear is shifted to 4th. |
Valve body is blocked up or stuck (sequence valve) Shift solenoid valve SLT remains open or closed Automatic transmission (clutch, brake or gear, etc.) |
- HINT:
| ECM command gearshift | 1st | 2nd | 3rd | 4th | 5th | 6th |
| Actual gear position under malfunction | ↑ | ↑ | ↑ | ↑ | ↑ | 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 |
| Actual gear position under fail-safe mode | ↑ | ↑ | ↑ | 3rd | 3rd | 3rd |
MONITOR DESCRIPTION
The ECM commands gear shifts by turning the shift solenoid valves "ON/OFF" and switching oil pressure to the valves in the valve body.
The DTC indicates that the sequence valve is locked in the direction the spring stretches and that shifting to the 6th gear is impossible.
INSPECTION PROCEDURE
| 1.CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0729) |
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 "P0729" is output A "P0729" and other DTCs B
- HINT:
- If any other codes besides "P0729" are output, perform troubleshooting for those DTCs first.
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| A | |
| 2.PERFORM ACTIVE TEST BY INTELLIGENT TESTER |
- 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 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 the Shift Position | [Test Details] Operate the shift solenoid valve and set each shift position by yourself. [Vehicle Condition] 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:
| Tester command gearshift | 1st | 2nd | 3rd | 4th | 5th | 6th |
| Actual gear position under malfunction | ↑ | ↑ | ↑ | ↑ | ↑ | 4th |
- OK:
- Gear position changes in accordance with the tester command.
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| OK | |
| 3.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.
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 | |
| 4.CLEAR THE DTC AND RUNNING TEST |
Clear the DTC, and check DTC again after conducting the "MONITOR DRIVE PATTERN FOR ECT TEST" .
- OK:
- No DTC code
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| OK | ||
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