2021 Mazda 3 BaseFACTORY OEM SERVICE PROCEDURE

Pcm Removal/Installation: Notes

WARNING: This page is about a different variant/trim than selected.
CAUTION:
  • When replacing the PCM, perform the configuration to assure that the system operates correctly. (See CONFIGURATION .)
  1. When replacing the PCM, perform the configuration using the following procedure.
    1. Connect the M-MDS to the DLC-2.
    2. Switch the ignition ON (engine off).
    3. Activate the MMDS and perform the following procedure.
      1. Press [Start] to start the vehicle identification.
      2. Press the [Toolbox] tab.
      3. Press the [Work Support] icon.
      4. Press [Configuration].
      5. Press [Run] to perform the configuration.
      6. Press [PCM].
      7. Verify that the ignition is switched ON (engine off) and press [Next].
        • If the ignition cannot be switched ON (engine off), leave it as it is and press [Next].
      8. When [Install the new ECU] is displayed, move to the PCM replacement procedure.
  2. Disconnect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .)
  3. Disconnect the PCM connectors. (See PCM Connector Connection Note .)
    G13714527Courtesy of MAZDA MOTORS CORP.
  4. Remove the clips from the PCM bracket.
    G13714528Courtesy of MAZDA MOTORS CORP.
  5. Remove the nuts.
    Fig 1: PCM Nuts With Torque Specification
    G13714529Courtesy of MAZDA MOTORS CORP.
  6. Remove the PCM.
  7. Remove the PCM bracket. (See PCM Bracket Installation Note .)
    Fig 2: PCM Bracket, Nut And Bolts With Torque Specification
    G13714530Courtesy of MAZDA MOTORS CORP.
  8. Install in the reverse order of removal.
  9. If the PCM is replaced, perform the following procedure.
    NOTE:
    • Depending on the vehicle conditions, the configuration after PCM replacement may use the data read from the PCM before replacement or the data as of shipment from manufacturer (As-Built data).
    • The data used for the configuration is displayed on the lower part of the M-MDS display when the configuration is completed.
    1. Continue to perform configuration following the instructions on the M-MDS screen.
    2. Perform the immobilizer system-related part programming using the M-MDS. (See IMMOBILIZER SYSTEM-RELATED PARTS PROGRAMMING (US) .)
    3. If the configuration is performed using the As-Built data, write the coupling component characteristic value. (See COUPLING COMPONENT CALIBRATION DATA WRITING .)
    4. Perform the DTC inspection. (See DTC INSPECTION .)
      • If a DTC is displayed, clear it. (See CLEARING DTC .)
        • If the DTC is displayed again, repair the malfunctioning location according to the applicable DTC troubleshooting.
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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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