2002 Mercury Villager BaseFACTORY OEM SERVICE PROCEDURE

Test ND: Engine Speed Signal: Testing

    NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  1. 1) Check RPM PID
    Turn ignition off. Connect scan tool to DLC. Start engine and allow to idle. Using scan tool, access RPM PID from PID/DATA MONITOR & RECORD menu. Monitor RPM PID while slowly depressing accelerator pedal. If RPM PID increases as accelerator pedal is depressed, go to next step. If RPM PID does not increase, fault may be ignition related. Go to TEST DR  , step  1).

  2. 2) Check CTO Circuit To Instrument Cluster For Open Or Short To Ground

    Turn ignition off. Disconnect PCM and TCM harness connectors. Inspect connectors for damaged pins and repair if necessary. Disconnect instrument cluster connector C266a (analog) or C267a (electronic). See Figure or Figure . Using DVOM, measure resistance of CTO circuit (Green/White wire) between PCM harness connector terminal No. 3 and instrument cluster harness connector C266a terminal No. 8 (analog) or C267a terminal No. 4 (electronic), and chassis ground. See Figure and Figure . If resistance is less than 5 ohms between PCM and instrument cluster, and more than 10 k/ohms between PCM and chassis ground, replace PCM. If resistance is 5 ohms or more between PCM and instrument cluster, and 10 k/ohms or less between PCM and chassis ground, repair open or short to ground in CTO circuit. See WIRING DIAGRAMS article.
    NOTE: A break in step numbering sequence occurs at this point. Procedure skips from step 2) to step 10). No test procedures have been omitted.
    3. NOTE: For additional testing information, see DIAGNOSTIC AIDS .

  3. 10) DTC P0725: Check ENG RPM PID Signal To TCM
    Connect scan tool to DLC. Start engine and allow to idle. Using scan tool, select DIAGNOSTIC DATA LINK. Select TCM-TRANSMISSION CTRL MODULE. Using scan tool, access ENG RPM PID from PID/DATA MONITOR & RECORD menu. Monitor ENG RPM PID signal while depressing accelerator pedal slowly. If ENG RPM PID changes according to accelerator pedal position, replace TCM. If ENG RPM PID does not change according to accelerator pedal position, go to next step.

  4. 11) Check CTO Circuit

    Turn ignition off. Disconnect TCM and PCM harness connectors. Inspect connectors for damaged pins and repair if necessary. Using DVOM, measure resistance of CTO circuit (Green/White wire) between TCM harness connector C277b terminal No. 15 and PCM harness connector terminal No. 3, and chassis ground. See Figure, Figure and Figure . If resistance is less than 5 ohms between TCM and PCM, and more than 10 k/ohms between TCM and chassis ground, replace TCM. If resistance is 5 ohms or more between TCM and PCM, and 10 k/ohms or less between TCM and chassis ground, repair open or short to ground in CTO circuit. See WIRING DIAGRAMS article.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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