Toyota Tundra Service Manual: Shift Solenoid "A" Performance (Shift Solenoid Valve S1) (P0751)

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

DTC Code

DTC Detection Condition

Trouble Area

P0751

  • 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 shifted to 5th.

  • Shift solenoid valve S1 remains closed
  • Valve body is blocked
  • Automatic transmission (clutch, brake, gear, etc.)

P0751

  • S1 stuck OFF malfunction*2:
  • The ECM determines there is a malfunction when conditions (a) and (b) are met (2-trip detection logic):

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

(b) When the ECM directs the transmission to switch to 6th gear, the engine overruns (clutch slips).

  • Shift solenoid valve S1 remains open
  • 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 solenoid valve mechanical problem:

    ECM gear shift command

    1st

    2nd

    3rd

    4th

    5th

    6th

    *1: Actual gear position under S1 stuck ON malfunction

    2nd

    2nd

    3rd

    4th

    5th

    6th

    *2: Actual gear position under 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 during S1 stuck ON malfunction

    2nd

    2nd

    3rd

    4th

    5th

    6th

    *2: Actual gear position under fail-safe mode during 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 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/Functional check

Required sensors/Components

Shift solenoid valve S1, Speed sensor (NT), Speed sensor (SP2), Crankshaft position sensor (NE), Throttle position sensor, MAF

Frequency of operation

Continuous

Duration

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

0.4 seconds

OFF malfunction (B)

3 seconds

OFF malfunction (C)

1 second

MIL operation

2 driving cycles

Sequence of operation

None

TYPICAL ENABLING CONDITIONS

All

The monitor will run whenever the following DTCs are not present

P0717 (Turbine speed sensor circuit)

P0722 (Output Speed Sensor circuit)

P0710, P0712, P0713, P2740, P2742, P2743 (ATF temperature sensor circuit)

P0973, P0974 (Shift solenoid valve S1 circuit)

P0976, P0977 (Shift solenoid valve S2 circuit)

P0979, P0980 (Shift solenoid valve S3 circuit)

P0982, P0983 (Shift solenoid valve S4 circuit)

P0985, P0986 (Shift solenoid valve SR circuit)

P0748 (Shift solenoid valve SL1 circuit)

P0778 (Shift solenoid valve SL2 circuit)

P0115, P0116, P0117, P0118, P011B (ECT (Engine coolant temperature) sensor circuit)

P0327, P0328, P032C, P032D (KCS sensor circuit)

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 higher

Spark advance from max. retard timing by KCS control

0° crankshaft angle or more

Engine

Starting

OFF Malfunction (A)

ECM selected gear

5th

Vehicle speed

2 km/h (1.2 mph) or more

Throttle valve opening angle

5% or more at 2000 rpm

(Conditions vary with engine speed)

Calculated load value

7.75% or more (A/C off)

7.75% or more (A/C on)

Input speed/output speed (NT/NO)

NT: Input (Turbine) speed

NO: Internal counter shaft speed

3.30 to 7.50

or

1.91 to 2.35

or

1.28 to 1.53

or

0.93 to 1.07

or

0.65 to 0.79

or

0.51 to 0.65

OFF Malfunction (B)

Current ECM selected gear

6th

Last ECM selected gear

5th

Vehicle speed (During transition from 5th to 6th gear)

Less than 100 km/h (62.2 mph)

OFF Malfunction (C)

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 (62.2 mph)

ON Malfunction (A)

ECM selected gear

1st

Vehicle speed

2 km/h (1.2 mph) or more and less than 40 km/h (24.9 mph)

Engine speed - Turbine speed (NE - NT)

50 rpm or more

Calculated load value

7.75% or more (A/C off)

7.75% or more (A/C on)

Input speed/output speed (NT/NO)

NT: Input (Turbine) speed

NO: Internal counter shaft speed

3.30 to 7.50

or

1.91 to 2.35

or

1.28 to 1.53

or

0.93 to 1.07

or

0.65 to 0.79

or

0.51 to 0.65

ON Malfunction (B)

ECM selected gear

5th

Vehicle speed

2 km/h (1.2 mph) or more

Throttle valve opening angle

5% or more at 2000 rpm

(Conditions vary with engine speed)

Calculated load value

7.75% or more (A/C off)

7.75% or more (A/C on)

Input speed/output speed (NT/NO)

NT: Input (Turbine) speed

NO: Internal counter shaft speed

3.30 to 7.50

or

1.91 to 2.35

or

1.28 to 1.53

or

0.93 to 1.07

or

0.65 to 0.79

or

0.51 to 0.65

TYPICAL MALFUNCTION THRESHOLDS

[OFF malfunction]
  • Both of the following conditions are met: OFF malfunction (A) and OFF malfunction (B) or (C)
OFF Malfunction (A)

Turbine speed / Output speed (NT / NO)

0.65 or more, and 0.79 or less

(This means actual gear is 5th)

OFF Malfunction (B)

Turbine speed - Output speed x 5th gear ratio

(NT - NO x 5th gear ratio)

1000 rpm or more

OFF Malfunction (C)

Turbine speed - Output speed x 6th gear ratio

(NT - NO x 6th gear ratio)

1000 rpm or more

[ON malfunction]
  • Both of the following conditions 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)

1.91 or more, and 2.35 or less

(This means actual gear is 2nd)

ON Malfunction (B)

Turbine speed / Output speed (NT / NO)

0.65 or more, and 0.79 or less

(This means actual gear is 5th)

CAUTION / NOTICE / HINT

NOTICE:

Perform the universal trip to clear permanent DTCs (See page ).

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 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.

Comparing the shift position commanded by the Active Test with the actual shift position enables you to confirm the problem (See page ).

Engine and ECT

Tester Display

Test Part

Control Range

Diagnostic Note

Control the Shift Position

Operate shift solenoid valves and set each shift position

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

Possible to check operation of the 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-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.
  • The 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 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 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.

B

GO TO DTC CHART

A

2.

PERFORM ACTIVE TEST USING TECHSTREAM (SHIFT SOLENOID VALVE SLT)

NG

REPLACE SHIFT SOLENOID VALVE SLT

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 12 V battery voltage 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

Text in Illustration

*a

Component without harness connected

(Shift Solenoid Valve S1)

NG

REPLACE SHIFT SOLENOID VALVE S1

OK

4.

INSPECT TRANSMISSION VALVE BODY ASSEMBLY

(a) Check the transmission valve body assembly.

OK:

There are no foreign objects on each valve.

OK

REPAIR OR REPLACE AUTOMATIC TRANSMISSION ASSEMBLY

NG

REPAIR OR REPLACE TRANSMISSION VALVE BODY ASSEMBLY

    Pressure Control Solenoid "A" Electrical (Shift Solenoid Valve SL1) (P0748)

    Shift Solenoid "B" Performance (Shift Solenoid Valve S2) (P0756)

    See More:

    Toyota Tundra Service Manual > Vehicle Stability Control System: Open in ABS Motor Relay Circuit (C146C)
    DESCRIPTION The ABS motor relay supplies power to the pump motor. While the ABS is activated, the skid control ECU (brake actuator assembly) turns the ABS motor relay on to operate the pump motor. If the voltage supplied to the ABS motor relay (+BM) is too low due to low voltage from the battery or ...

    Toyota Tundra Owners Manual

    Toyota Tundra Service Manual

    © 2021 Copyright www.ttundra.com
    0.0187