2004 Mazda MX-5 Miata Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Circuit Open/Short Inspection

  1. Remove the PCM. See PCM REMOVAL/INSTALLATION .
  2. Inspect the following wiring harnesses for an open or short circuit by probing the applicable sensor and PCM terminals with ohmmeter leads.
    • If there is an open or short circuit, repair or replace wiring harnesses.
    • If there is no open or short circuit, replace the CMP sensor.

      Open Circuit 

    • CMP signal circuit (CMP sensor connector terminal B and PCM connector terminal 3V).
      Fig 1: Identifying PCM (24 Pin & 31 Pin), CMP & Main Relay Sensor Harness Side Connector Terminals
      G00989740Courtesy of MAZDA MOTORS CORP.
    • Power circuit (CMP sensor connector terminal A and main relay terminal D through common connector).
    • GND circuit (CMP sensor connector terminal C and PCM connector terminal 4A).

      Short Circuit 

      • NOTE: For connector terminals, see Fig 1.
    • CMP signal circuit (CMP sensor connector terminal B and PCM connector terminal 3V to GND).
    • Power circuit (CMP sensor connector terminal A and main relay terminal D through common connector to GND).
  3. Reconnect the CMP sensor connector.
  4. Inspect the protrusion of camshaft (intake side) for damage and cracks.
Factory Service Tools

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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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