2021 Mazda 3 BaseFACTORY OEM SERVICE PROCEDURE

Relay And Fuse Block Removal/Installation: Installation

  1. Move the flathead screwdriver in the direction of the arrow (1) shown in the figure, and pull the wiring harness in the direction of the arrow (2) while pressing the stopper to detach the relay or fuse terminal from the stopper.
    G13561127Courtesy of MAZDA MOTORS CORP.
  2. Relocate all relay and fuse terminals to the new relay and fuse block.
    CAUTION:
    • If terminals are installed incorrectly, it could damage electrical accessories and burn wiring harnesses. When relocating terminals after replacing the relay and fuse block, line up the relay and fuse blocks of old and news parts and always verify each of the wiring harnesses in the wiring diagram so that the installation positions are correct.
    • A terminal disconnection could cause electronic components and the system to not operate normally due to poor contact. After terminal relocation, lightly pull the wiring harnesses to verify that they cannot be pulled out.
    G13561158Courtesy of MAZDA MOTORS CORP.
  3. Connect the wiring harness connectors.
    G13179912Courtesy of MAZDA MOTORS CORP.
  4. Install the bolt shown in the figure and install the power supply cable.
    Fig 1: Power Supply Cable Bolt With Torque Specification
    G13561160Courtesy of MAZDA MOTORS CORP.
  5. Insert the relay and fuse block middle cover into the relay and fuse block.
    G13561161Courtesy of MAZDA MOTORS CORP.
  6. Insert all the relay and fuse block tabs into the relay and fuse block middle cover and install the relay and fuse block middle cover.
  7. Insert the wiring harness connectors into the relay and fuse block middle cover.
    G13718424Courtesy of MAZDA MOTORS CORP.
  8. Install all the wiring harness connectors to the relay and fuse block middle cover.
    G13179908Courtesy of MAZDA MOTORS CORP.
  9. Insert all the relay and fuse block middle cover tabs into the relay and fuse block lower cover and install the relay and fuse block lower cover.
    G13561163Courtesy of MAZDA MOTORS CORP.
  10. Install the wiring harness clip to the relay and fuse block lower cover.
    G13561164Courtesy of MAZDA MOTORS CORP.
  11. Install the band shown in the figure.
    G13561165Courtesy of MAZDA MOTORS CORP.
  12. Insert the front wiring harness protector into the stud bolts.
    G13561166Courtesy of MAZDA MOTORS CORP.
  13. Insert the front wiring harness protector cap into the stud bolt.
    G13561167Courtesy of MAZDA MOTORS CORP.
  14. Install the front wiring harness protector clip tabs to the body.
    G13561168Courtesy of MAZDA MOTORS CORP.
  15. Insert the relay and fuse block into the stud bolts.
    G13179926Courtesy of MAZDA MOTORS CORP.
  16. Install nut A.
  17. Install nut B.
  18. Install nut C.
    Fig 2: Relay And Fuse Block Nuts With Torque Specification
    G13179927Courtesy of MAZDA MOTORS CORP.
  19. Connect the wiring harness connectors.
    G13718404Courtesy of MAZDA MOTORS CORP.
  20. Install the relay and fuse block upper cover.
  21. Install the parts removed in Steps 2 and 3 in "REMOVAL". (See REMOVAL .)
  22. Perform the "Verify Relay and Fuse Block Replacement". (See VERIFY RELAY AND FUSE BLOCK REPLACEMENT .)
  23. Connect the negative battery terminal. (See NEGATIVE BATTERY TERMINAL DISCONNECTION/CONNECTION (US) .)
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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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