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  • P0720 Output Speed Sensor Error

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    Mopar1973Man

    P0720 OUTPUT SPEED SENSOR ERROR

    When Monitored and Set Condition:

    When Monitored: The transmission gear ratio is monitored continuously while the transmission is in gear.
    Set Condition: If there is an excessive change in output RPM in any gear. This DTC can take up to five minutes of problem identification before illuminating the MIL.

    POSSIBLE CAUSES

    • OUTPUT SPEED SENSOR SIGNAL CIRCUIT OPEN
    • SPEED SENSOR GROUND CIRCUIT OPEN
    • OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO GROUND
    • SPEED SENSOR GROUND CIRCUIT SHORT TO GROUND
    • OUTPUT SPEED SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE
    • SPEED SENSOR GROUND CIRCUIT SHORT TO VOLTAGE
    • OUTPUT SPEED SENSOR
    • POWERTRAIN CONTROL MODULE
    • INTERMITTENT WIRING AND CONNECTORS

    DIAGNOSTIC PROCEDURE

    NOTE: Low fluid level can be the cause of many transmission problems. If the fluid level is low locate and repair the leak then check and adjust the fluid level. Refer to appropriate AUTOMATIC TRANSMISSION article.

    NOTE: Always perform diagnostics with a fully charged battery to avoid false symptoms.

    NOTE: Diagnose 1 Trip Failures as a fully matured DTC.

    NOTE: Verify flash level of Powertrain Controller. Some problems are corrected by software upgrades to the Transmission and Engine Systems.

    NOTE: Due to the integration of the Powertrain and Transmission control modules - if a controller flash is performed it is necessary to perform STANDARD PROCEDURE - TCM QUICK LEARN and the STANDARD PROCEDURE - DRIVE LEARN . Failure to do so may result in shift quality complaints.

    NOTE: Check for applicable TSB's that may apply.

    1. With the DRBIII(R), read the engine DTC's. Check and repair all Engine DTC's prior to performing Transmission symptom diagnostics. With the DRBIII(R), read Transmission DTC's. Record all DTC's and 1 Trip Failures. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors. Repair as necessary. Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test for SYMPTOM: P0706-CHECK SHIFTER SIGNAL For Gear Ratio DTC's, check and record all CVI's. Most DTC's set on start up but some must be set by driving the vehicle to ensure that all diagnostic monitors have run. Perform this procedure prior to Symptom diagnosis. Continue Go To 2
    2. Turn the ignition off to the lock position.
      CAUTION: Properly support the vehicle and raise all drive wheels off the ground.
      Start the engine in park. Place the transmission gear selector in drive, release foot from brake.
      WARNING: BE SURE TO KEEP HANDS AND FEET CLEAR OF ROTATING WHEELS.
      With the DRBIII(R), monitor the Output Speed Sensor RPM. Is the Output Speed Sensor RPM below 100 RPM?
      Yes --> Go To 3
      No --> Go To 12
    3. Turn the ignition off to the lock position. Remove the Starter Relay.
      NOTE: Removal of the Starter Relay is to prevent a Transmission, NO RESPONSE, condition and disable the starter.
      Install the Transmission Simulator, Miller tool #8333.
      NOTE: Check connectors - Clean/repair as necessary.
      Ignition on, engine not running.With the Transmission Simulator, set the selector switch to 3000/1000 and the Input/Output switch to ON. With the DRBIII(R), 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 --> Go To 4
      No --> Go To 5
    4. If there are no possible causes remaining, view repair.

    Repair

    Replace the Output Speed Sensor. Refer to appropriate AUTOMATIC TRANSMISSION article. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    1. Turn the ignition off to the lock position. Disconnect the PCM C4 harness connector. Disconnect the Output Speed Sensor harness connector.
      NOTE: Check connectors - Clean/repair as necessary.
      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 MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
      Measure the resistance of the Output Speed Sensor Signal circuit from the Output Speed Sensor harness connector to the appropriate terminal of special tool #8815. Is the resistance above 5.0 ohms?
      Yes --> Repair the Output Speed Sensor Signal circuit for an open. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
      No --> Go To 6
    2. Turn the ignition off to the lock position. Disconnect the PCM C4 harness connector. Disconnect the Output Speed Sensor harness connector.
      NOTE: Check connectors - Clean/repair as necessary.
      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 MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
      Measure the resistance between ground and the Output Speed Sensor Signal circuit. Is the resistance Below 5.0 ohms?
      Yes --> Repair the Output Speed Sensor Signal circuit for a short to ground. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
      No --> Go To 7
    3. Turn the ignition off to the lock position. Disconnect the PCM C4 harness connector. Remove the Transmission Control Relay.
      CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WELL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
      NOTE: Check connectors - Clean/repair as necessary.
      Place a jumper wire between the Fused B+ circuit and the Transmission Relay Output circuit in the Transmission Control Relay connector. Ignition on, engine not running. Measure the voltage of the Output Speed Sensor Signal circuit. Is the voltage above 0.5 volts?
      Yes --> Repair the Output Speed Sensor Signal circuit for a short to voltage. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
      No --> Go To 8
    4. Turn the ignition off to the lock position. Disconnect the PCM C4 harness connector. Disconnect the Output Speed Sensor harness connector.
      NOTE: Check connectors - Clean/repair as necessary.
      CAUTION: DO NOT PROBE THE PCM HARNESS CONNECTORS. PROBING THE PCM HARNESS CONNECTORS WELL DAMAGE THE PCM TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION. INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
      Measure the resistance of the Speed Sensor Ground circuit from the Output Speed Sensor harness connector to the appropriate terminal in the special tool #8815. Is the resistance above 5.0 ohms?
      Yes --> Repair the Speed Sensor Ground circuit for an open. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
      No --> Go To 9
    5. Turn the ignition off to the lock position. Disconnect the PCM C4 harness connector. Disconnect the Output Speed Sensor harness connector.
      NOTE: Check connectors - Clean/repair as necessary.
      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 MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
      Measure the resistance between ground and the Speed Sensor Ground circuit. Is the resistance below 5.0 ohms?
      Yes --> Repair the Speed Sensor Ground circuit for a short to ground. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
      No --> Go To 10
    6. Turn the ignition off to the lock position. Disconnect the PCM C4 harness connector. Remove the Transmission Control Relay from the PDC.
      NOTE: Check connectors - Clean/repair as necessary.
      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 MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
      Place a jumper wire between the Fused B+ circuit and Transmission Control Relay Output circuit in the Transmission Control Relay connector. Ignition on, engine not running. Measure the voltage of the Speed Sensor Ground circuit. Is the voltage above 0.5 volts?
      Yes --> Repair the Speed Sensor Ground circuit for a short to voltage. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
      No --> Go To 11
    7. Using the schematics as a guide, inspect the wiring and connectors. Repair as necessary. Pay particular attention to all power and ground circuits. If there are no possible causes remaining, view repair.

    Repair

    Replace the Powertrain Control Module and perform STANDARD PROCEDURE - TCM QUICK LEARN . Refer to ELECTRONIC CONTROL MODULES . Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .

    1. The conditions necessary to set this DTC are not present at this time. Using the schematics as a guide, inspect the wiring and connectors specific to this circuit. Wiggle the wires while checking for shorted and open circuits. With the DRBIII(R), check the EATX DTC EVENT DATA to help identify the conditions in which the DTC was set. Were there any problems found?
      Yes --> Repair as necessary. Perform (NGC) 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
      No --> Test Complete.


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