P0729

TX6A AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: P0729; Gear 6 Incorrect Ratio; 2013 MY FR-S [03/2012 -]
P0729 - Gear 6 Incorrect Ratio

SYSTEM DESCRIPTION

The TCM uses signals from the transmission revolution sensor (SP2) and transmission revolution sensor (NT) to detect the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th 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 or gear, etc.).





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






* Gear position during fail-safe operation:
If any malfunction is detected, the TCM changes into the fail-safe mode to shift into the gear positions as shown in the table below.






MONITOR DESCRIPTION

The TCM 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.

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

The following items are common to all conditions below.





TYPICAL MALFUNCTION THRESHOLDS

Compare target gear instructed from TCM and gear ratio calculated from turbine shaft speed and vehicle speed.

* Both of the following condition are met: Condition (A) and (B)

Condition (A)





*
Condition (B)





* Both of the following condition are met: Condition (C) and (D)

Condition (C)





*
Condition (D)





INSPECTION PROCEDURE

NOTICE:
Perform the universal trip to clear permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

PROCEDURE

1. CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0729)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON and push the Techstream main switch on.

(c) Read the DTCs using the Techstream Reading and Clearing Diagnostic Trouble Codes.

Result:





B -- GO TO DTC CHART TX6A Automatic Transmission
A -- Continue to next step.

2. CHECK THE GEAR POSITION

(a) Drive the vehicle with shift lever in the M.

(b) Check the shift position.





HINT
* Perform the test at the normal operating ATF (Automatic Transmission Fluid) temperature: 60 to 90°C (140 to 194°F)
* Perform under condition that A/C is off.

OK:

Gear position changes.

NG -- REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.

3. HYDRAULIC TEST









NOTICE:
* Perform the test at the normal operating ATF (Automatic Transmission Fluid) temperature: 60 to 90°C (140 to 194°F)
* The line pressure test should always be carried out in pairs. One technician should observe the conditions of wheels or wheel stoppers outside the vehicle while the other is performing the test.
* Be careful to prevent SST hose from interfering with the exhaust pipe.
* This Check must be conducted after checking and adjusting engine.
* Perform under condition that A/C is OFF.
* When conducting stall test, do not continue more than 5 seconds.

(a) Warm up the ATF (Automatic Transmission Fluid).

(b) Lift the vehicle up.

(c) Remove the test plug on the transmission case center right side and connect SST.

SST : 09992-00095

09992-00231

09992-00271

(d) Lower the vehicle.

(e) Fully apply the parking brake and check the 4 wheels.

(f) Connect the Techstream to the DLC3.

(g) Turn the ignition switch to ON and turn the Techstream on.

(h) Enter the following menus: Powertrain / ECT / Data List / Engine Speed.

(i) Start the engine and check idling speed.

(j) Keep your left foot pressing firmly on the brake pedal and shift into D position.

(k) Measure the line pressure when the engine is idling.

(l) Depress the accelerator pedal all the way down. Quickly read the highest line pressure when engine speed reaches stall speed.

(m) In the same manner, do the test in R position.

Specified line pressure:





NG -- REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal
OK -- Continue to next step.

4. CLEAR THE DTC AND RUNNING TEST

(a) Clear the DTC, and check DTC again after conducting the "MONITOR DRIVE PATTERN FOR ECT TEST" Monitors, Trips, Drive Cycles and Readiness Codes.

OK:

No DTC code

NG -- REPLACE TRANSMISSION VALVE BODY ASSEMBLY Removal

OK -- END