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Home › Chrysler › 2002 › Intrepid Base › Repair and Diagnosis › Transmission › Automatic Trans › Automatic Transmission Diagnosis › Diagnostic Tests › DTC P0720: Output Speed Sensor Error › Diagnostic Procedure

Diagnostic Procedure

  1. Place gearshift lever in "P" position and start engine. Raise and support drive wheels. Place gearshift lever in "D" position and release brake. Using scan tool, monitor output speed sensor value. If value is less than 100 RPM, go to next step. If value is 100 RPM or greater, go to step  9.
    2. NOTE: Failure to remove starter relay can cause a NO RESPONSE FROM TCM condition.
  2. Turn ignition switch to LOCK position. Remove starter relay from power distribution center. See Figure. This prevents vehicle from starting in gear. Install Transmission Simulator (8333). Turn ignition on. Using transmission simulator, turn rotary knob to middle (1250/3000) position. Turn INPUT/OUTPUT SPEED switch on. Using scan tool, monitor input and output speed sensor values. If input speed sensor value is 2950-3050 RPM and output speed sensor value is 1200-1300 RPM, replace output speed sensor. See REMOVAL & INSTALLATION in appropriate SERVICING article in AUTOMATIC TRANSMISSIONS. If speed sensor values are not as specified, disconnect transmission simulator and go to next step.
  3. Turn ignition switch to LOCK position. Disconnect PCM harness connector C4. See Figure. Disconnect output speed sensor harness connector. Measure resistance of output speed sensor signal circuit between output speed sensor connector terminal No. 2 and PCM harness connector C4 terminal No. 32 using Miller Special Tool (8815). If resistance is greater than 5 ohms, repair open circuit. If resistance is 5 ohms or less, go to next step.
  4. Measure resistance of output speed sensor ground circuit between output speed sensor connector terminal No. 1 and PCM harness connector C4 terminal No. 34 using Miller Special Tool (8815). If resistance is greater than 5 ohms, repair open circuit. If resistance is 5 ohms or less, go to next step.
  5. Measure resistance between ground and output speed sensor signal circuit (terminal No. 2). If resistance is less than 5 ohms, repair circuit for short to ground. If resistance is 5 ohms or greater, go to next step.
  6. Remove transmission control relay from power distribution center. See Figure. Using fused jumper wire, jumper fused B+ circuit and transmission relay output circuit together at transmission control relay connector. See WIRING DIAGRAMS . Turn ignition on. Measure voltage between ground and output speed sensor signal circuit at PCM harness connector C4 terminal No. 32 using Miller Special Tool (8815). If voltage is greater than .5 volt, repair circuit for short to voltage. If voltage is .5 volt or less, go to next step.
  7. Measure voltage between ground and output speed sensor ground circuit at PCM harness connector C4 terminal No. 34 using Miller Special Tool (8815). If voltage is greater than .5 volt, repair circuit for short to voltage. If voltage is .5 volt or less, go to next step.
  8. If no other potential causes for DTC P0720 remain, PCM is assumed to be faulty. Repair or replace as necessary. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION.
  9. Conditions necessary to set DTC are not present at this time. Using wiring diagram as a guide, inspect wiring and connectors associated with circuits in question. See WIRING DIAGRAMS . Wiggle wires while checking for shorted and open circuits. Repair as necessary. If circuits are okay, testing is complete.
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