Last Modified: 11-29-2007 1.6 C
Service Category: Drivetrain Section: Automatic Transmission/Transaxle
Model Year: 2008 Model: Sequoia Doc ID: RM000000W8I01UX
Title: AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 Sequoia)

DTC

P0729

Gear 6 Incorrect Ratio

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 Detection 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)

(a) When the ECM directs the transmission to switch to 5th gear, the actual gear is also shifted to 5th.

(b) When the ECM directs the transmission 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:

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

    ECM command gearshift

    1st

    2nd

    3rd

    4th

    5th

    6th

    Actual gear position under malfunction

    1st

    2nd

    3rd

    4th

    5th

    4th
  • Gear position during fail-safe operation:

    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

    1st

    2nd

    3rd

    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 6th gear is impossible.

MONITOR STRATEGY

Related DTCs

P0729: Gear 6 incorrect ratio (Sequence valve) / Rationality check

Required sensors/Components

Sequence valve

Frequency of operation

Continuous

Duration

0.4 seconds

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not present

P0500: VSS

P0748 - P0799: Trans solenoid (range)

Turbine speed sensor circuit

Not circuit malfunction

Output speed sensor circuit

Not circuit malfunction

Shift solenoid valve S1 circuit

Not circuit malfunction

Shift solenoid valve S2 circuit

Not circuit malfunction

Shift solenoid valve S3 circuit

Not circuit malfunction

Shift solenoid valve S4 circuit

Not circuit malfunction

Shift solenoid valve SR circuit

Not circuit malfunction

Shift solenoid valve SL1 circuit

Not circuit malfunction

Shift solenoid valve SL2 circuit

Not circuit malfunction

ECT (Engine coolant temperature) sensor circuit

Not circuit malfunction

KCS sensor circuit

Not circuit malfunction

ETCS (Electric Throttle Control System)

Not system down

Transmission position

"D"

Duration time from shifting "N" to "D"

4 seconds or more

ECT

40°C (104°F) or more

Spark advance from max. retard timing by KCS control

0° crankshaft angle or more

Engine

Starting

Transfer position

HIGH*

HINT:

*: Following conditions met

Vehicle speed sensor circuit

Not circuit malfunction

Output shaft speed sensor circuit

Not circuit malfunction

Transfer output speed

143 rpm or more

Transfer input speed/Transfer output speed (NO/NOtf)

0.9 or more, and less than 1.1

Condition (A)

ECM selected gear

5th

Vehicle speed

2 km/h (1.3 mph) or more

Throttle valve opening angle

9% or more at 2000 rpm

(Conditions vary with engine speed)

Condition (B)

ECM selected gear

6th

Vehicle speed

2 km/h (1.3 mph) or more

Throttle valve opening angle

9% or more at 2000 rpm

(Conditions vary with engine speed)

TYPICAL MALFUNCTION THRESHOLDS

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

Condition (A)

Turbine speed/Output speed (NT/NO)

0.66 or more, and 0.80 or less

(This means actual gear is 5th)

Condition (B)

Turbine speed/Output speed (NT/NO)

0.93 or more, and 1.07 or less

(This means actual gear is 4th)

INSPECTION PROCEDURE

PROCEDURE

1.

CHECK DTC OUTPUT (IN ADDITION TO DTC P0729)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

(e) 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 other codes besides P0729 are output, perform troubleshooting for those DTCs first.

A

2.

PERFORM ACTIVE TEST USING TECHSTREAM (RUNNING TEST)

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 Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

(a) Warm up the engine.

(b) Turn the ignition switch off.

(c) Connect the Techstream to the DLC3.

(d) Turn the ignition switch to ON.

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.

(g) According to the display on the Techstream, perform the Active Test.

HINT:

While driving, the shift position can be forcibly changed with the Techstream.

Engine and ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Control the Shift Position

Operate shift solenoid valve and set each shift position by yourself
  • Press "→" button: Shift up
  • Press "←" button: Shift down

Possible to check operation of shift solenoid valves

[Vehicle Condition]

50 km/h (30 mph) or less

HINT:

  • This test can be conducted when the vehicle speed is 50 km/h (30 mph) or less.
  • The 4th to 5th and 5th to 6th up-shift must be performed with the accelerator pedal released.
  • The 6th to 5th and 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 ECM is shown in the Data List display on the Techstream.
  • Gear positions in the event of a solenoid valve mechanical problem:

    Tester command gearshift

    1st

    2nd

    3rd

    4th

    5th

    6th

    Actual gear position under malfunction

    1st

    2nd

    3rd

    4th

    5th

    4th

OK:

Gear position changes in accordance with the tester command.

OK

3.

PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT)

NOTICE:

  • Perform the test at the normal operating ATF temperature: 50 to 80°C (122 to 176°F).
  • Be careful to prevent SST hose from interfering with the exhaust pipe.
  • Perform the 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 Tests early in troubleshooting is one way to save diagnostic time. Data List information can be displayed while performing Active Tests.

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

SST: 09992-00095

09992-00231

09992-00271

(b) Connect the Techstream to the DLC3.

(c) Start the engine and warm it up.

(d) Measure the line pressure with SST.

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine and ECT / Active Test.

(g) According to the display on the Techstream, perform the Active Test.

(h) Measure the line pressure.

Engine and ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Activate the Solenoid (SLT)*

Operate the shift solenoid SLT and raise line pressure

ON or OFF

HINT:

  • OFF: Line pressure up (when Active Test "Activate the Solenoid (SLT)" is performed, ECM commands SLT solenoid to turn OFF)
  • ON: No action (normal operation)

[Vehicle Condition]

  • Vehicle stopped
  • Engine idling

HINT:

*: 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 AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: HYDRAULIC TEST (2008 Sequoia) as well. Please 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.

OK

4.

CLEAR DTC AND PERFORM RUNNING TEST

(a) Clear the DTC AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DTC CHECK / CLEAR (2008 Sequoia) .

(b) Check the DTC again after conducting the Monitor Drive Pattern AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: MONITOR DRIVE PATTERN (2008 Sequoia) .

OK:

No DTC code output.

OK