2005 Mazda MX-5 Miata Base, AutomaticFACTORY OEM SERVICE PROCEDURE

Wave Profile Inspection

  1. Remove the PCM. (See PCM REMOVAL/INSTALLATIONΒ .)
  2. Connect WDS or equivalent to DLC-2 connector.
  3. Connect oscilloscope test leads to the following PCM connector terminals.
    • (+) lead: PCM terminal 3V
    • (-) lead: PCM terminal 4A
  4. Start the engine.
  5. Monitor RPM PID.
    Fig 1: Identifying PCM Connector Terminal
    G03638007Courtesy of MAZDA MOTORS CORP.
  6. Inspect wave profile when idling engine.
    • If wave profile or voltage are out of specifications, carry out the "Circuit Open/Short Inspection".
      • PCM terminal: 3V(+) <--> 4A(-)
      • Oscilloscope setting: 2.0V/DIV(Y), 20ms/DIV(X), DC range
      • Vehicle condition: Idling
    Fig 2: Identifying Waveform Graph
    G03638008Courtesy of MAZDA MOTORS CORP.
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:

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

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