DTC P0729: Gear 6 Incorrect Ratio [04/2013 - 08/2015]: Procedure

WARNING: This page is about a different car, the 2015 Lexus IS 250 and 2014 Lexus IS 250. However, it is still accessible from the selected car via links, so may be relevant.

CHECK OTHER DTCS OUTPUT

Connect the Techstream to the DLC3.
Turn the engine switch on (IG).
Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
Powertrain > Engine > Trouble Codes

Read the DTCs using the Techstream.

Result

Result	Proceed to
Only P0729 is output	A
P0729 and other DTCs are output	B

HINT:

If any DTCs other than P0729 are output, perform troubleshooting for those DTCs first.

Result:

GO TO DTC CHART. Refer to DIAGNOSTIC TROUBLE CODE CHART [04/2013 - 06/2014] , or refer to DIAGNOSTIC TROUBLE CODE CHART [06/2014 - 08/2015]

Result:

See step 2

PERFORM ACTIVE TEST USING TECHSTREAM

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.

Warm up the engine.
Turn the engine switch off.
Connect the Techstream to the DLC3.
Turn the engine switch on (IG).
Turn the Techstream on.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Shift Position.
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.

Refer to FAIL-SAFE CHART [04/2013 - 08/2015]

According to the display on the Techstream, perform the "Active Test".

Powertrain > Engine > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Control the Shift Position	Operate the shift solenoid valve and set the each shift position.	Press "→" button: Shift up Press "←" button: Shift down	Possible to check the operation of the shift solenoid valves. [Vehicle Condition] Less than 50 km/h (31 mph)

Powertrain > Engine > Active Test

Tester Display
Control the Shift Position

HINT:

This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
The 4th to 5th and 5th to 6th up-shifts must be performed with the accelerator pedal released.
The 6th to 5th and 5th to 4th down-shifts 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 (Shift Status) display on the Techstream.

Gear positions in the event of a solenoid valve mechanical problem:

Tester commanded gear	1st	2nd	3rd	4th	5th	6th
Actual gear under malfunction	1st	2nd	3rd	4th	5th	4th

Gear position changes in accordance with the tester command.

Result

Proceed to
OK
NG

Result:

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY. Refer to COMPONENTS [04/2013 - 08/2015]

Result:

See step 3

PERFORM ACTIVE TEST USING TECHSTREAM

NOTE:

Perform this test with the ATF (Automatic Transmission Fluid) at the normal operating temperature: 50 to 80°C (122 to 176°F)
Be careful to prevent the SST hose from contacting the exhaust pipe.
This check must be conducted after checking confirming that the engine is normal.
Perform this 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 Test early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing 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.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Lower the vehicle.
Fully apply the parking brake and chock the 4 wheels.
Connect the Techstream to the DLC3.
Start the engine.
Warm up the ATF (Automatic Transmission Fluid).
Measure the line pressure with the engine idling.
Turn the Techstream on.
Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the Solenoid(SLT).
According to the display on the Techstream, perform the "Active Test".

Measure the line pressure with SST.

Powertrain > Engine > Active Test

Tester Display	Measurement Item	Control Range	Diagnostic Note
Activate the Solenoid (SLT)	Operate the shift solenoid SLT and raise the line pressure.	ON or OFF HINT: OFF: Line pressure up (when Active Test "Activate the Solenoid (SLT)" performed, ECM commands shift solenoid valve SLT to turn off) ON: No action (normal operation)	[Vehicle Condition] IG ON Engine idling

Powertrain > Engine > Active Test

Tester Display
Activate the Solenoid (SLT)

"Activate the Solenoid (SLT)" in the Active Test is performed to check the line pressure changes with SST connected to the automatic transmission, which is used in the HYDRAULIC TEST as well.

Refer to HYDRAULIC TEST [04/2013 - 08/2015]

HINT:

The pressure values in Active Test and HYDRAULIC TEST are different from each other.

The line pressure changes as specified when performing the Active Test.

Result

Proceed to
OK
NG

Result:

REPLACE SHIFT SOLENOID VALVE SLT. Refer to COMPONENTS [04/2013 - 08/2015]

Result:

See step 4

CHECK IF DTC OUTPUT RECURS

Clear the DTCs, and check for DTCs again after conducting the "MONITOR DRIVE PATTERN FOR ECT TEST".

Refer to MONITOR DRIVE PATTERN [04/2013 - 08/2015]

Result

Result	Proceed to
DTC P0729 is not output	A
DTC P0729 is output	B

Result:

END

Result:

REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY. Refer to COMPONENTS [04/2013 - 08/2015]