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Home >> Jeep >> 2009 >> Wrangler X, Automatic >> Repair and Diagnosis >> Transmission >> Automatic Trans >> (Transmission Control Module (TCM) - Electrical Diagnostics) >> DTC Troubleshooting >> P0721-Output Speed Sensor Circuit Performance >> Diagnostic Test
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Diagnostic Test

  1. CHECK TO SEE IF DTC P0721 IS CURRENT 
    1. Turn the ignition off to the lock position.
      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 step  2

      No 

      • Go to step  9
  2. OUTPUT SPEED SENSOR 
    1. Turn the ignition off to the lock position.
    2. Remove the Ignition Switch Feed fuse from the TIPM.
      CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.
      WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in possible serious or fatal injury.
    3. Install the Transmission Simulator 8333.
    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 

      No 

      • Go to step  3
  3. CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR AN OPEN 
    Fig 1: Checking Output Speed Sensor Signal Circuit
    GC0106901Courtesy of CHRYSLER LLC
    1. Turn the ignition off to the lock position.
    2. Disconnect the Transmission Simulator 8333.
    3. Disconnect the PCM harness connectors and connect the PCM Pinout Box 8815.
      CAUTION: Do not probe the PCM harness connectors. Probing the PCM harness connectors will damage the PCM terminals resulting in poor terminal to pin connection. Install the PCM Pinout Box 8815 to perform diagnosis.
    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 Pinout Box 8815.

      Is the resistance above 5.0 Ohms?

      Yes 

      No 

      • Go to step  4
  4. CHECK THE (T13) SPEED SENSOR GROUND CIRCUIT FOR AN OPEN 
    Fig 2: Checking Sensor Ground Circuit
    GC0106898Courtesy of CHRYSLER LLC
    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 Pinout Box 8815.

      Is the resistance above 5.0 Ohms?

      Yes 

      No 

      • Go to step  5
  5. CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT FOR A SHORT TO GROUND 
    Fig 3: Checking Output Speed Sensor Signal Circuit
    GC0106902Courtesy of CHRYSLER LLC
    1. Measure the resistance between ground and the (T14) Output Speed Sensor Signal circuit.

      Is the resistance below 5.0 Ohms?

      Yes 

      No 

      • Go to step  6
  6. CHECK THE (T13) SPEED SENSOR GROUND CIRCUIT FOR A SHORT TO GROUND 
    Fig 4: Checking Speed Sensor Ground Circuit
    GC0106900Courtesy of CHRYSLER LLC
    1. Measure the resistance between ground and the (T13) Speed Sensor Ground circuit.

      Is the resistance below 5.0 Ohms?

      Yes 

      No 

      • Go to step  7
  7. CHECK THE (T14) OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE 
    Fig 5: Checking Output Speed Sensor Signal Circuit
    GC0111713Courtesy of CHRYSLER LLC
    1. Ignition on, engine not running.
    2. With the scan tool in TIPM, actuate the TCM output.
    3. Measure the voltage of the (T14) Output Speed Sensor Signal circuit.

      Is the voltage above 0.5 of a volt?

      Yes 

      No 

      • Go to step  8
  8. CHECK THE (T13) SPEED SENSOR GROUND CIRCUIT FOR A SHORT TO VOLTAGE 
    Fig 6: Checking Speed Sensor Ground Circuit
    GC0111712Courtesy of CHRYSLER LLC
    1. With the scan tool in TIPM, actuate the TCM output.
    2. Measure the voltage of the (T13) Speed Sensor Ground circuit.

      Is the voltage above 0.5 of a volt?

      Yes 

      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 545RFE TRANSMISSION VERIFICATION TEST. See DTC-Based Diagnostics/MODULE, Transmission Control (TCM) - 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 

      No 

      • Test Complete.
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