Home › Drivetrain › Automatic Transmission/Transaxle › AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM
Last Modified: 11-27-2007 1.6 C
Service Category: Drivetrain Section: Automatic Transmission/Transaxle
Model Year: 2008 Model: LX570 Doc ID: RM000000W8J03VX
Title: AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: DESCRIPTION (2008 LX570)

DTC

P0751

Shift Solenoid "A" Performance (Shift Solenoid Valve S1)

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 with the shift solenoid valves, valve body or automatic transmission (clutch, brake, gear, etc.).

DTC Code

DTC Detection Condition

Trouble Area

P0751

A shift solenoid valve S1 stuck ON malfunction*1:

The ECM determines there is a malfunction when the following conditions are both met (2-trip detection logic).

(a) When the ECM directs the transmission to switch to 1st gear, the actual gear is shifted to 2nd.

(b) When the ECM directs the transmission to switch to 5th gear, the actual gear is also shifted to 5th.
  • Shift solenoid valve S1 remains open
  • Valve body is blocked
  • Automatic transmission (clutch, brake, gear, etc.)

P0751

A shift solenoid valve S1 stuck OFF malfunction*2:

The ECM determines there is a malfunction when conditions (a) and (b), or (a) and (c) are met (2-trip detection logic).

(a) When the ECM directs the transmission to switch to 2nd gear, the actual gear is shifted to 1st.

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

(c) When the ECM directs the transmission to switch to 6th gear, the engine overruns (clutch slips).
  • Shift solenoid valve S1 remains closed
  • Shift solenoid valve SLT remains open or closed
  • Valve body is blocked
  • No. 2 brake malfunction (Driving is difficult.)
  • Automatic transmission (clutch, brake, gear, etc.)

HINT:

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

    ECM gear shift command

    1st

    2nd

    3rd

    4th

    5th

    6th

    *1: Actual gear position under shift solenoid valve S1 stuck ON malfunction

    2nd

    2nd

    3rd

    4th

    5th

    6th

    *2: Actual gear position under shift solenoid valve S1 stuck OFF malfunction

    1st

    1st

    3rd

    4th

    5th

    N*

    N*: Neutral

  • 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

    *1: Actual gear position under fail-safe mode when shift solenoid valve S1 stuck ON malfunction

    2nd

    2nd

    3rd

    4th

    5th

    6th

    *2: Actual gear position under fail-safe mode when shift solenoid valve S1 stuck OFF malfunction

    1st*3

    1st*3

    3rd

    3rd

    3rd

    3rd

    *3: Under engine braking, downshifting to 1st or 2nd gear is prohibited.

MONITOR DESCRIPTION

This DTC indicates a "stuck ON malfunction" or "stuck OFF malfunction" of shift solenoid valve S1.

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 the same, the ECM illuminates the MIL and stores the DTC.

MONITOR STRATEGY

Related DTCs

P0751:

Shift solenoid valve S1/OFF malfunction

Shift solenoid valve S1/ON malfunction

Required sensors/Components

Shift solenoid valve S1, Speed sensor (NT), Speed sensor (NC), Crankshaft position sensor (NE), Throttle position sensor MAF

Frequency of operation

Continuous

Duration

OFF malfunction (A), (B) and ON malfunction (A), (B)

0.4 sec.

OFF malfunction (C)

3 sec.

OFF malfunction (D)

1 sec.

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

ALL

The monitor will run whenever the following DTCs are not stored

P0115 - P0118 (ECT sensor)

P0125 (Insufficient ECT for Closed Loop)

P0500 (VSS)

P0748 - P0798 (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 sec. or more

ECT

40°C (104°F) or higher

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

OFF malfunction (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)

OFF malfunction (B)

ECM selected gear

2nd

Vehicle speed

2 km/h (1.3 mph) or more

Output speed

2nd → 1st down-shift point or more

Throttle valve opening angle

9% or more at 2000 rpm

(Conditions vary with engine speed)

OFF malfunction (C)

Current ECM selected gear

6th

Last ECM selected gear

5th

Vehicle speed

(During transition from 5th to 6th gear)

Less than 100 km/h (62.1 mph)

OFF malfunction (D)

ECM selected gear

6th

Engine speed-Turbine speed (NE-NT)

(After transition from 5th to 6th gear)

150 rpm or less

Vehicle speed

(After transition from 5th to 6th gear)

Less than 100 km/h (62.1 mph)

ON malfunction (A)

ECM selected gear

1st

Vehicle speed

2 km/h (1.3 mph) or more, and less than 40 km/h (24.8 mph)

Engine speed-Turbine speed (NE-NT)

50 rpm or more

ON malfunction (B)

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)

TYPICAL MALFUNCTION THRESHOLDS

[OFF malfunction]

When both of the following conditions are met: OFF malfunction (A) and OFF malfunction (B), (C) or (D)

OFF malfunction (A)

Turbine speed/Output speed (NT/NO)

0.66 or more, and 0.80 or less

(This means actual gear is 5th)

OFF malfunction (B)

Turbine speed/Output speed (NT/NO)

3.11 or more, and 7.58 or less

(This means actual gear is 1st)

OFF malfunction (C)

Turbine speed-Output speed x 5th gear ratio

(NT-NO x 5th gear ratio)

1000 rpm or more

OFF malfunction (D)

Turbine speed-Output speed x 6th gear ratio

(NT-NO x 6th gear ratio)

1000 rpm or more

[ON malfunction]

When both conditions below are met: ON malfunction (A) and (B)

2 detections are necessary per driving cycle:

1st detection: temporary flag ON

2nd detection: pending fault code ON

ON malfunction (A)

Turbine speed/Output speed (NT/NO)

1.83 or more, and 2.27 or less

(This means actual gear is 2nd)

ON malfunction (B)

Turbine speed/Output speed (NT/NO)

0.66 or more, and 0.80 or less

(This means actual gear is 5th)

INSPECTION PROCEDURE

1. ACTIVE 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 engine switch off.

(c) Connect the Techstream to the DLC3.

(d) Turn the engine switch on (IG).

(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.

Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: AUTOMATIC TRANSMISSION SYSTEM: FAIL-SAFE CHART (2008 LX570) .

Engine and ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Control the Shift Position

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

It is possible to check the operation of the shift solenoid valves.

[Vehicle Condition]

The vehicle speed is 50 km/h (31 mph) or less.

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 display on the Techstream.
  • Shift solenoid valve S1 turns ON/OFF normally when the shift lever is in D.

    ECM gear shift command

    1st

    2nd

    3rd

    4th

    5th

    6th

    Shift solenoid valve S1

    OFF

    ON

    ON

    ON

    ON

    ON

PROCEDURE

1.

CHECK DTC OUTPUT (IN ADDITION TO DTC P0751)

(a) Connect the Techstream to the DLC3.

(b) Turn the engine switch on (IG).

(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 P0751 is output

A

P0751 and other DTCs are output

B

HINT:

If any other codes besides P0751 are output, perform troubleshooting for those DTCs first.

A

2.

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 turned 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 shift solenoid valve SLT and raise line pressure

ON or OFF

HINT:

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

[Vehicle Condition]

  • The vehicle is stopped.
  • The engine is 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 LX570) as well. 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

3.

INSPECT SHIFT SOLENOID VALVE S1

(a) Remove shift solenoid valve S1.

(b) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

Shift solenoid valve S1 connector terminal - Shift solenoid valve S1 body

20°C (68°F)

11 to 15 Ω

(c) Apply battery voltage (12 V) to the shift solenoid valve and check that the valve moves and makes an operating noise.

OK:

Measurement Condition

Specified Condition
  • Battery positive (+) → Shift solenoid valve S1 connector
  • Battery negative (-) → Shift solenoid valve S1 body

Valve moves and makes an operating noise
OK

4.

INSPECT TRANSMISSION VALVE BODY ASSEMBLY

(a) Check the transmission valve body assembly AB60F AUTOMATIC TRANSMISSION / TRANSAXLE: VALVE BODY ASSEMBLY: DISASSEMBLY (2008 LX570) .

OK:

There are no foreign objects on any valve.

OK