Last Modified: 4-30-2014 6.6 C Doc ID: RM000000W8J00HX
Model Year: 2006 Model: LX470 Prod Date Range: [05/2005 -           ]
Title: A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: P0751; Shift Solenoid "A" Performance (Shift Solenoid Valve S1); 2006 MY LX470 [05/2005 -        ]

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 or 5th 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

P0751

Gear required by the ECM does not match the actual gear when driving (2 trip detection logic)
  • Shift solenoid valve S1 remains open or closed
  • Valve body is blocked
  • Automatic transmission (clutch, brake or gear, etc.)

MONITOR DESCRIPTION

This DTC indicates a stuck ON malfunction or stuck OFF malfunction of the 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, Vehicle sensor, Throttle position sensor, Speed sensor (NT), Speed sensor (NO)

Frequency of operation

Continuous

Duration

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

0.4 sec.

OFF malfunction (C)

Immediate

ON malfunction (D)

3 sec.

ON malfunction (E)

0.5 sec.

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

The following conditions are common to all conditions below.

The monitor will run whenever this DTC is not present.

P0115 - P0118: ECT sensor

P0125: Insufficient ECT for Closed Loop

P0500: VSS

P0748 - P0798: Trans solenoid (range)

Turbine speed sensor (NT) circuit

Not circuit malfunction

Output speed sensor (NO) circuit

Not circuit malfunction

Shift solenoid valve S1 circuit

Not circuit malfunction

Shift solenoid valve S2 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 range

"D"

ECT

40°C (104°F) or more

Spark advance from Max. retard timing by KCS control

0°crankshaft angle or more

Engine

Starting

Transfer range

"HIGH" *

Transfer range "HIGH" * (This condition is applied only 4WD)

* Following conditions met

Vehicle speed sensor "A" circuit

Not circuit malfunction

Output shaft speed sensor circuit

Not circuit malfunction

Transfer output speed

143 rpm or more

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

0.9 to 1.1

OFF malfunction (A)

ECM selected gear

1st

Vehicle speed

2 to 40 km/h (1.2 to 24.9 mph)

Throttle valve opening angle

8% or more and

7% or more at 2,000 rpm

(Conditions vary with engine speed)

Calculated load value

7.75% or more

OFF malfunction (B)

Current ECM selected gear

5th

Last ECM selected gear

4th

Continuous time for ECM selecting 4th gear

2 sec. or more

Actual gear when ECM selected 4th gear

4th

OFF malfunction (C)

Current ECM selected gear

5th

Last ECM selected gear

4th

ON malfunction (A)

ECM selected gear

1st

Vehicle speed

2 to 40 km/h (1.2 to 24.9 mph)

Throttle valve opening angle

7% or more at 2,000 rpm

(Conditions vary with engine speed)

ON malfunction (B)

ECM selected gear

4th

Vehicle speed

2 km/h (1.2 mph) or more

Throttle valve opening angle

7% or more at 2,000 rpm

(Conditions vary with engine speed)

ON malfunction (C)

ECM selected gear

3rd

Vehicle speed

2 km/h (1.2 mph) or more

Throttle valve opening angle

7% or more at 2,000 rpm

(Conditions vary with engine speed)

Calculated load value

7.75% or more

ON malfunction (D)

Current ECM selected gear

5th

Last ECM selected gear

4th

Vehicle speed

(During transition from 4th to 5th gear)

Less than 100 km/h (62.2 mph)

ON malfunction (E)

ECM selected gear

5th

Engine speed - Turbine speed (NE - NT)

(After transition from 4th to 5th gear)

Less than 150 rpm

Vehicle speed

(After transition from 4th to 5th gear)

Less than 100 km/h (62.2 mph)

TYPICAL MALFUNCTION THRESHOLDS

OFF malfunction:

All of the following are met: Conditions (A), (B) and (C)

2 detections are necessary per driving cycle:

1st detection; temporary flag ON

2nd detection; pending fault code ON

OFF malfunction (A)

Turbine speed/Output speed (NT/NO)

0.93 to 1.07

OFF malfunction (B)

Turbine speed/Output speed (NT/NO)

0.65 to 0.79

OFF malfunction (C)

Output record from ECM for 4th → 5th upshifting

Recorded

ON malfunction:

Either of the following conditions is met:

- ON malfunction (A) and (B)

- ON malfunction (B) or (C), and ON malfunction (D) or (E)

ON malfunction (A) and (B)

Turbine speed/Output speed (NT/NO)

3.30 to 7.50

ON malfunction (C)

Turbine speed/Output speed (NT/NO)

1.91 to 2.35

ON malfunction (D)

Turbine speed - Output speed x 4th gear ratio

(NT - NO x 4th gear ratio)

1,000 rpm or more

ON malfunction (E)

Turbine speed - Output speed x 5th gear ratio

(NT - NO x 5th gear ratio)

1,000 rpm or more

INSPECTION PROCEDURE

HINT:

Performing the intelligent tester's ACTIVE TEST allows relay, VSV, actuator and other items to be operated without removing any parts. Performing the ACTIVE TEST early in troubleshooting is one way to save time.

The DATA LIST can be displayed during the ACTIVE TEST.

  1. Warm up the engine.
  2. Turn the ignition switch OFF.
  3. Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.
  4. Turn the ignition switch ON.
  5. Turn the intelligent tester ON.
  6. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST.
  7. 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 2006 MY LX470 [05/2005 -        ]; A750F AUTOMATIC TRANSMISSION: AUTOMATIC TRANSMISSION SYSTEM: FAIL-SAFE CHART .

Item

Test Details

Diagnostic Note

SHIFT

[Test Details]

Operate the shift solenoid valve and set each shift position by yourself

[Vehicle Condition]

  • IDL: ON
  • Less than 50 km/h (31 mph)

[Other information]

  • Press "→" button: Shift up
  • Press "←" button: Shift down

Possible to check the operation of the shift solenoid valves

HINT:

  • This test can be conducted when the vehicle speed is 50 km/h (31 mph) or less.
  • The 4th to 5th up-shift must be performed with the accelerator pedal released.
  • The 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 (shift status) display on the intelligent tester.
  • The shift solenoid valve S1 turns ON/OFF normally when the shift lever is on D:

    ECM gear shift command

    1st

    2nd

    3rd

    4th

    5th

    Shift solenoid valve S1

    ON

    ON

    OFF

    OFF

    OFF

PROCEDURE

1.

CHECK OTHER DTCS OUTPUT (IN ADDITION TO DTC P0751)

(a) Connect the intelligent tester to the CAN VIM. Then connect the CAN VIM to the DLC3.

(b) Turn the ignition switch ON and push the intelligent tester main switch ON.

(c) Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.

(d) Read the DTCs using the intelligent tester.

Display (DTC output)

Proceed to

Only P0751 is output

A

P0751 and other DTCs

B

HINT:

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

B

GO TO DTC CHART

A

2.

INSPECT SHIFT SOLENOID S1

(a) Remove the shift solenoid valve S1.

(b) Measure the resistance between the solenoid valve terminal and solenoid valve body.

Standard resistance:

11 to 15 Ω at 20°C (68°F)

(c) Connect the battery's positive (+) lead to the terminal of the solenoid connector, and the negative (-) lead to the solenoid body.

OK:

Solenoid makes an operating noise.

NG

REPLACE SHIFT SOLENOID S1

OK

3.

INSPECT TRANSMISSION VALVE BODY ASSEMBLY

OK:

There are no foreign objects on each valve.

NG

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

OK

REPLACE AUTOMATIC TRANSMISSION ASSEMBLY