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Home >> Chrysler >> 2011 >> 300 C, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 431 (Powertrain Control Module (Pcm) - Electrical Diagnostics - 68RFE Automatic Transmission - 2500 Hd & 3500) >> Diagnosis And Testing >> P0721-Output Speed Sensor Circuit Performance >> Diagnostic Test

Diagnostic Test

WARNING: This page is about a different car, the 2013 RAM 3500 HD and 2013 RAM 2500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. CHECK TO SEE IF DTC P0721 IS CURRENT 
    1. Turn the ignition off.
      CAUTION:

      Properly support the vehicle and raise all drive wheels off the ground.

    2. Release the parking brake.
    3. Start the engine in park.
    4. Place the transmission gear selector in drive, release foot from brake.
      WARNING:

      Be sure to keep hands and feet clear of rotating wheels.

    5. With the scan tool, monitor the Output Speed Sensor rpm.

      Is the Output Speed Sensor rpm below 100 rpm?

      Yes 

      • Go To  2

      No 

      • Go To  9
  2. OUTPUT SPEED SENSOR 
    1. Turn the ignition off.
    2. Remove the Starter Relay from the PDC.
      CAUTION:

      Removal of the Starter Relay will prevent the vehicle from being started in gear.

      WARNING:

      The Starter Relay must be removed from the PDC. Failure to do so may result in possible serious or fatal injury.

    3. Install the Transmission Simulator (special tool #8333B, Simulator, Transmission).
    4. Ignition on, engine not running.
    5. With the Transmission Simulator, set the selector switch to 3000/1000 and the Input/Output switch to ON.
    6. With the scan tool, monitor the Input and Output Speed Sensor rpm

      Does the Input Speed read 3000 rpm and the Output Speed read 1000 rpm, ± 50 rpm?

      Yes 

      • Replace the Output Speed Sensor in accordance with the Service Information.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Go To  3
  3. CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR AN OPEN 
    1. Turn the ignition off.
    2. Disconnect the Transmission Simulator (special tool #8333B, Simulator, Transmission).
    3. Disconnect the PCM C2 harness connector.
    4. Measure the resistance of the (T14) Output Speed Sensor Signal circuit from the Output Speed Sensor harness connector to the appropriate terminal of the PCM C2 harness connector.

      Is the resistance above 5.0 Ohms?

      Yes 

      • Repair the (T14) Output Speed Sensor Signal circuit for an open.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Go To  4
  4. CHECK THE (T13) SPEED SENSOR GROUND CIRCUIT FOR AN OPEN 
    1. Measure the resistance of the (T13) Speed Sensor Ground circuit from the Output Speed Sensor harness connector to the appropriate terminal in the PCM C2 harness connector.

      Is the resistance above 5.0 Ohms?

      Yes 

      • Repair the (T13) Speed Sensor Ground circuit for an open.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Go To  5
  5. CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    1. Measure the resistance between ground and the (T14) Output Speed Sensor Signal circuit.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Repair the (T14) Output Speed Sensor Signal circuit for a short to ground.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Go To  6
  6. CHECK THE (T13) SPEED SENSOR GROUND CIRCUIT FOR A SHORT TO GROUND 
    1. Measure the resistance between ground and the (T13) Speed Sensor Ground circuit.

      Is the resistance below 5.0 Ohms?

      Yes 

      • Repair the (T13) Speed Sensor Ground circuit for a short to ground.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Go To  7
  7. CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE 
    1. Ignition on, engine not running.
    2. Measure the voltage of the (T14) Output Speed Sensor Signal circuit.

      Is the voltage above 0.5 of a volt?

      Yes 

      • Repair the (T14) Output Speed Sensor Signal circuit for a short to voltage.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Go To  8
  8. CHECK THE (T13) SPEED SENSOR GROUND CIRCUIT FOR A SHORT TO VOLTAGE 
    1. Measure the voltage of the (T13) Speed Sensor Ground circuit.

      Is the voltage above 0.5 of a volt?

      Yes 

      • Repair the (T13) Speed Sensor Ground circuit for a short to voltage.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Using the schematics as a guide, check the Powertrain Control Module (PCM) terminals for corrosion, damage, or terminal push out. Pay particular attention to all power and ground circuits. If no problems are found, replace and program the PCM in accordance with the Service Information. With the scan tool, perform Quick Learn.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .
  9. CHECK THE WIRING AND CONNECTORS 
    1. The conditions necessary to set this DTC are not present at this time.
    2. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
    3. Wiggle the wires while checking for shorted and open circuits.
    4. With the scan tool, check the Event Data to help identify the conditions in which the DTC was set.

      Were there any problems found?

      Yes 

      • Repair as necessary.
      • Perform the 68RFE TRANSMISSION VERIFICATION TEST. Refer to STANDARD PROCEDURE  .

      No 

      • Test Complete.
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