AUTOMATIC TRANSAXLE SYSTEM, Diagnostic DTC:P0791, P0793

DESCRIPTION

This sensor detects the rotation speed of the counter gear which shows the output speed of transaxle. By comparing the input turbine speed signal (NT) with the counter gear speed sensor signal (NC), the ECM detects the shift timing of the gears and appropriately controls the engine torque and hydraulic pressure according to various conditions, thus, providing smooth gear shifts.

MONITOR DESCRIPTION

The NT terminal of the ECM detects a revolution signal from the speed sensor (NT) (input RPM). The ECM calculates a gear shifts by comparing the speed sensor (NT) with the 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 revolution is less than 300 rpm*1 although the output shaft revolution is more than 1000 rpm*2, the ECM interprets this as a fault, illuminates the MIL and stores the DTC.

*1: Pulse is not output or is irregularly output.

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

WIRING DIAGRAM

INSPECTION PROCEDURE

1. DATA LIST

   Tech Tips

   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 / Engine and ECT / Data List.

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

      Engine and ECT

      Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
      SPD (NC)	Counter Gear Speed/ Min.: 0 rpm Max.: 12750 rpm	-	Data is displayed in increments of 50 rpm

      Tech Tips

      
      

      • 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 (SPEED SENSOR INSTALLATION)

   
   

   1. Remove the valve body assembly.

   2. 

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

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

   
   

   NG

   REPAIR OR REPLACE TRANSMISSION REVOLUTION SENSOR Click here

   OK

2. INSPECT TRANSMISSION WIRE

   
   
   1. 

      Text in Illustration

      *a	Component without harness connected (Transmission Wire)
      *b	Wiring Harness Connector Side
      *c	Sensor Side

      Disconnect the speed sensor connector from the transmission wire.

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

      Standard Resistance
      Tester Condition Condition Specified Condition 3 (NCO) sensor side - A-3 (NCO) wiring harness connector side Always Below 1 Ω 4 (NCB) sensor side - A-4 (NCB) wiring harness connector side Always Below 1 Ω 3 (NCO) sensor side - Body ground and other terminals Always 10 kΩ or higher 4 (NCB) sensor side - Body ground and other terminals Always 10 kΩ or higher

   
   

   NG

   REPLACE TRANSMISSION WIRE Click here

   OK

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

   
   

   1. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Condition Condition Specified Condition E26-118 (NCB) - E8-4 (NCB) Always Below 1 Ω E26-117 (NCO) - E8-3 (NCO) Always Below 1 Ω E26-118 (NCB) or E8-4 (NCB)- Body ground and other terminals Always 10 kΩ or higher E26-117 (NCO) or E8-3 (NCO) - Body ground and other terminals Always 10 kΩ or higher

   
   

   NG

   REPAIR OR REPLACE HARNESS OR CONNECTOR

   OK

4. INSPECT WIRING HARNESS CONNECTOR

   
   

   1. Remove the wiring harness connector.

   2. 

      Text in Illustration

      *a	Component without harness connected (Wiring Harness Connector)
      *b	ECM Side
      *c	Transmission Wire Side

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

      Standard Resistance
      Tester Condition Condition Specified Condition E8-3 (NCO) - A-3 (NCO) Always Below 1 Ω E8-4 (NCB) - A-4 (NCB) Always Below 1 Ω E8-3 (NCO) - All other terminals Always 10 kΩ or higher E8-4 (NCB) - All other terminals Always 10 kΩ or higher

   
   

   NG

   REPLACE WIRING HARNESS CONNECTOR Click here

   OK

5. REPLACE TRANSMISSION REVOLUTION SENSOR

   Click here.

   
   

   NEXT

6. CHECK IF DTC OUTPUT RECURS (SEE IF DTC P0791 AND/OR P0793 IS OUTPUT AGAIN)

   
   

   1. Connect the intelligent tester to the DLC3.

   2. Start the engine and turn the intelligent tester on.

   3. Clear the DTCs Click here.

      Tech Tips

      Write down the currently output DTCs before clearing them.

   4. Perform the monitor drive pattern Click here.

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

   6. Read the DTCs using the intelligent tester.

      Result
      Display (DTC Output) Proceed to Only "P0791 or P0793" is output A No output B

   
   

   B

   END

   A

   REPLACE ECM Click here