AUTOMATIC TRANSAXLE SYSTEM, Diagnostic DTC:P0791 and P0793

DTC Code DTC Name
P0791 Intermediate Shaft Speed Sensor "A" Circuit
P0793 Intermediate Shaft Speed Sensor "A"

DESCRIPTION

This sensor detects the rotation speed of the counter gear which indicates the output speed of the transaxle. By comparing the input turbine speed (speed sensor NT) signal with the counter gear speed (speed sensor NC) signal, the ECM detects the shift timing of the gears and appropriately controls the engine torque and hydraulic pressure according to various conditions. As a result, the gears shift smoothly.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0791

Intermediate Shaft Speed Sensor "A" Circuit

The speed sensor input voltage is either higher than 1.9 V or below 0.1 V for 2 sec. or more (1-trip detection logic).

  • Speed sensor NC (transmission revolution sensor)

  • Transmission wire

  • Wiring harness connector

  • ECM

Comes on

DTC stored

P0793

Intermediate Shaft Speed Sensor "A"

When the vehicle speed is 25 km/h (15.54 mph) or more, the counter gear speed is less than 300 rpm for 2 sec. or more (1-trip detection logic).

  • Speed sensor NC (transmission revolution sensor)

  • Transmission wire

  • Wiring harness connector

  • ECM

Comes on

DTC stored

MONITOR DESCRIPTION

The NT terminal of the ECM detects a pulse signal from speed sensor NT (input RPM). The ECM calculates gear shifts by comparing the signal from speed sensor NT with the signal from speed sensor NC.

While the vehicle is operating in 2nd, 3rd, 4th or 5th gear with the shift lever in D, if the input shaft speed is less than 300 rpm*1 although the output shaft speed is more than 1000 rpm*2, the ECM interprets this as a fault, illuminates the MIL and stores the DTC.

Tip:

  • *1: A pulse is not output or is irregularly output.

  • *2: The vehicle speed is 50 km/h (31 mph) or more.

WIRING DIAGRAM

Refer to DTC P0715.

Click here

CAUTION / NOTICE / HINT

Note:

Perform registration and/or initialization when parts related to the automatic transaxle are replaced.

Click here

  1. DATA LIST

    Tip:

    Using the GTS to read the Data List allows the values or states of switches, sensors, actuators and other items to be read without removing any parts. This non-intrusive inspection can be very useful because intermittent conditions or signals may be discovered before parts or wiring is disturbed. Reading the Data List information early in troubleshooting is one way to save diagnostic time.

    Note:

    In the table below, the values listed under "Normal Condition" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

    1. Warm up the engine.

    2. Turn the ignition switch off.

    3. Connect the GTS to the DLC3.

    4. Turn the ignition switch to ON.

    5. Turn the GTS on.

    6. Enter the following menus: Powertrain / Engine and ECT / Data List.

    7. According to the display on the GTS, read the Data List.

      Powertrain > Engine and ECT > Data List

      Tester Display

      Measurement Item

      Range

      Normal Condition

      Diagnostic Note

      SPD (NC)

      Counter gear speed (speed sensor NC)

      Min.: 0 rpm

      Max.: 12750 rpm

      0 rpm: Vehicle stopped

      The data is displayed in increments of 50 rpm.

      NC Sensor Voltage

      Speed sensor NC output voltage

      Min.: 0 V

      Max.: 5 V

      0.1 to 1.9 V: Engine idling

      -

      Powertrain > Engine and ECT > Data List

      Tester Display

      SPD (NC)

      NC Sensor Voltage
      Tip:

      • SPD (NC) is always 0 while driving: Open or short in the sensor or circuit.

      • SPD (NC) is always more than 0 and less than 300 rpm while driving the vehicle at 50 km/h (31 mph) or more: Sensor trouble, improper installation, or intermittent connection trouble of the circuit.

PROCEDURE

  1. INSPECT TRANSMISSION REVOLUTION SENSOR INSTALLATION

    1. Remove the transmission valve body assembly.

      Click hereClick here

    2. C133219

      Make sure that the connector is properly connected, and check the transmission revolution sensor installation.

      OK

      The installation bolts are tightened properly and there is no clearance between the sensor and transaxle case.

    Result

    Proceed to

    OK

    NG
    NG

    SECURELY INSTALL OR REPLACE TRANSMISSION REVOLUTION SENSOR

    Click here

    OK

  2. INSPECT TRANSMISSION WIRE

    1. C206824C05

      *1

      Transmission Wire

      *a

      Transmission Revolution Sensor Side

      *b

      Wiring Harness Connector Side

      Disconnect the transmission revolution sensor connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      NCB transmission revolution sensor side - A-4 (NCB) wiring harness connector side

      Always

      Below 1 Ω

      NCO transmission revolution sensor side - A-3 (NCO) wiring harness connector side

      Always

      Below 1 Ω

      NCB transmission revolution sensor side or A-4 (NCB) wiring harness connector side - Body ground and other terminals

      Always

      10 kΩ or higher

      NCO transmission revolution sensor side or A-3 (NCO) wiring harness connector side - Body ground and other terminals

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE TRANSMISSION WIRE

    Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (WIRING HARNESS CONNECTOR - ECM)

    1. Disconnect the B78 wiring harness connector.

    2. Disconnect the B77 ECM connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      B78-4 (NCB) - B77-118 (NCB)

      Always

      Below 1 Ω

      B78-3 (NCO) - B77-117 (NCO)

      Always

      Below 1 Ω

      B78-4 (NCB) or B77-118 (NCB) - Body ground and other terminals

      Always

      10 kΩ or higher

      B78-3 (NCO) or B77-117 (NCO) - Body ground and other terminals

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT WIRING HARNESS CONNECTOR

    1. Remove the wiring harness connector.

      C267935C02

      *1

      Wiring Harness Connector

      -

      -

      *a

      Transmission Wire Side

      *b

      ECM Side

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      A-4 (NCB) - B78-4 (NCB)

      Always

      Below 1 Ω

      A-3 (NCO) - B78-3 (NCO)

      Always

      Below 1 Ω

      A-4 (NCB) - All other terminals except B78-4 (NCB)

      Always

      10 kΩ or higher

      A-3 (NCO) - All other terminals except B78-3 (NCO)

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE WIRING HARNESS CONNECTOR

    Click hereClick here

    OK

  5. REPLACE TRANSMISSION REVOLUTION SENSOR

    1. Replace the transmission revolution sensor.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  6. CHECK IF DTC OUTPUT RECURS (DTC P0791 OR P0793)

    1. Connect the GTS to the DLC3.

    2. Start the engine and turn the GTS on.

    3. Clear the DTCs.

      Click here

      Tip:

      Write down the currently output DTCs before clearing them.

      Powertrain > Engine and ECT > Clear DTCs

    4. Perform the monitor drive pattern.

      Click here

    5. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

      Powertrain > Engine and ECT > Trouble Codes

    6. Read the DTCs using the GTS.

      Result

      Result

      Proceed to

      Only P0791 or P0793 is output

      A

      DTCs are not output

      B
    A

    REPLACE ECM

    Click here

    B

    END