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СИСТЕМА АВТОМАТИЧЕСКОЙ ТРАНСМИССИИ, Diagnostic DTC:P0791, P0793

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

Table 1. Text in Illustration
*1 Counter Gear *2 Clutch Drum
*3 Speed Sensor NC *4 Speed Sensor NT
DTC Code DTC Detection Condition Trouble Area
P0791 When the speed sensor input voltage is either higher than 1.9 V or below 0.1 V for 2 seconds or more (1-trip detection logic).

  • Speed sensor NC (speed sensor)

  • Transmission wire

  • TCM
P0793 When the vehicle speed is 25 km/h (15.5 mph) or more, the counter gear speed is less than 300 rpm for 2 seconds or more (1-trip detection logic).
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MONITOR DESCRIPTION

The NT terminal of the TCM detects a pulse signal from the speed sensor NT (input RPM). The TCM 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 TCM 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.

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WIRING DIAGRAM

Refer to DTC P0715 (Click here).

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INSPECTION PROCEDURE


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  1. DATA LIST

    Tip:

    Using the intelligent tester 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 intelligent tester to the DLC3.

    4. Turn the ignition switch to ON.

    5. Turn the intelligent tester on.

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

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

      Table 2. ECT
      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      SPD (NC)

      Counter gear speed (speed sensor NC)/

      Min.: 0 rpm

      Max.: 12750 rpm

      		 Vehicle stopped: 0 km/h (0 mph) The data is displayed in increments of 50 rpm.
      NC Sensor Voltage

      Counter gear speed sensor (speed sensor NC) output voltage/

      Min.: 0 V

      Max.: 5 V

      		 Engine idling: 0.1 to 1.9 V -
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PROCEDURE


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    INSPECT SPEED SENSOR NC INSTALLATION


    1. A01INDO

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

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

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    INSPECT TRANSMISSION WIRE


    1. A01ISH6E05

      Disconnect the speed sensor connector.

    2. Remove the TCM.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      NCB speed sensor side - 4 (NCB) TCM side Always Below 1 Ω
      NCO speed sensor side - 3 (NCO) TCM side Always Below 1 Ω
      NCB speed sensor side - Body ground Always 10 kΩ or higher
      NCO speed sensor side - Body ground Always 10 kΩ or higher
      NCB speed sensor side - All other terminals except 4 (NCB) TCM side Always 10 kΩ or higher
      NCO speed sensor side - All other terminals except 3 (NCO) TCM side Always 10 kΩ or higher
      Table 3. Text in Illustration
      *1 Transmission Wire
      *a Speed Sensor Side
      *b TCM Side

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    REPLACE SPEED SENSOR NC (SPEED SENSOR)


    1. Replace the speed sensor (Click here).


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    CHECK IF DTC OUTPUT RECURS (DTC P0791 OR P0793)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the intelligent tester on.

    4. Enter the following menus: Powertrain / ECT / DTC / Clear.

      Tip:

      Write down the currently output DTCs before clearing them.

    5. Perform the monitor drive pattern (Click here).

    6. Enter the following menus: Powertrain / ECT / DTC.

    7. Read the DTCs using the intelligent tester.

      Table 4. Result
      Result Proceed to
      Only P0791 or P0793 is output A
      DTCs are not output B

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    REPLACE TCMClick here

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    SECURELY INSTALL OR REPLACE SPEED SENSOR NCClick here

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    REPLACE TRANSMISSION WIREClick here

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    END