This procedure covers removal and replacement of the engine bay fuse box assembly on the 2014-2019 Toyota Corolla with the 1.8L I4 engine.

Warnings

Tools required

Parts

• Engine bay fuse box assembly × 1 — Use OEM specification
• Fuse box cover × 1 — Included with fuse box or reuse existing
• Ground strap (if corroded) × 1 — Use OEM specification

Preparation

1. Park vehicle on level surface and engage parking brake
2. Turn ignition to OFF position and remove key
3. Open hood and secure with prop rod
4. Photograph fuse box from multiple angles for reference
5. Disconnect negative battery terminal and secure cable away from battery post
6. Wait minimum 90 seconds for electrical system discharge
7. Remove fuse box cover and photograph fuse/relay layout
8. Document all fuse and relay positions using fuse box diagram on cover

Procedure

1. 1

   Remove all fuses and relays
   Using the fuse box diagram as reference, carefully remove all fuses and relays from the engine bay fuse box. Use a fuse puller tool or needle-nose pliers if needed. Place fuses and relays in organized container or labeled bags corresponding to their positions. Check each fuse for continuity and replace any blown fuses during reinstallation.
2. 2

   Disconnect primary harness connectors
   Locate the large multi-pin harness connectors on the bottom and sides of the fuse box. Press release tabs and carefully disconnect each connector. There are typically 2-3 large connectors. Apply light penetrating oil if connectors are difficult to release. Avoid pulling on wires - always grasp the connector body.
   ⚠Release tabs may be stiff on higher mileage vehicles - use flathead screwdriver wrapped in cloth to gently pry if needed
3. 3

   Remove terminal bolt connections
   Identify and remove all terminal bolt connections at the fuse box. These are typically on the side of the box for high-amperage circuits. Use 10mm socket to remove terminal bolts. Note wire positions and terminal orientation before removal.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)
4. 4

   Disconnect ground strap
   Locate the ground strap connection on the fuse box mounting area. Use 12mm or 14mm socket to remove ground strap bolt. Inspect ground strap and mounting surface for corrosion. Clean contact surfaces with wire brush if reusing. Replace ground strap if heavily corroded or damaged.
   ℹ️Ground connection integrity is critical for proper electrical system operation - ensure clean metal-to-metal contact
   Torque spec

   Ground Strap Bolts12 Nm (9 lb-ft)
5. 5

   Remove battery positive cable connection
   The main battery positive cable typically connects directly to the fuse box. Use 12mm socket to remove the positive cable terminal bolt from the fuse box. Secure cable away from work area to prevent accidental contact.
   ⚠️Even with battery disconnected, this cable carries stored charge - avoid contact with ground or metal surfaces
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)
6. 6

   Remove fuse box mounting bolts
   Locate the fuse box mounting bolts securing the assembly to the inner fender or mounting bracket. There are typically 2-3 bolts. Use 10mm or 12mm socket with extension to access bolts. Remove all mounting bolts and set aside.
   ⚠Support fuse box during bolt removal to prevent dropping and damaging connectors or wiring
   Torque spec

   Module Mounting Bolts8 Nm (6 lb-ft)
7. 7

   Remove fuse box assembly
   Carefully lift fuse box assembly from mounting location. Check for any remaining wire ties, clips, or connectors still attached. Maneuver assembly out of engine bay, routing around hoses and wiring as needed. Inspect mounting bracket and clean any corrosion or debris.
8. 8

   Prepare new fuse box
   Compare new fuse box to old unit to verify correct part. Transfer any brackets, clips, or mounting hardware from old box to new box if not included. Clean all mounting surfaces and connector areas on new fuse box with electrical contact cleaner.
9. 9

   Install new fuse box assembly
   Position new fuse box assembly into mounting location, routing wiring harnesses as photographed during removal. Align mounting holes with bracket. Thread mounting bolts by hand first to ensure proper alignment, then tighten to specification using torque wrench.
   Torque spec

   Module Mounting Bolts8 Nm (6 lb-ft)
10. 10

    Reconnect battery positive cable
    Connect main battery positive cable to fuse box terminal. Ensure terminal is clean and free of corrosion. Install terminal bolt and tighten to specification. Verify connection is secure and cable has no excess tension.
    Torque spec

    Battery Terminal Bolts6 Nm (4 lb-ft)
11. 11

    Reconnect ground strap
    Position ground strap to mounting location. Ensure both contact surfaces are clean and bare metal is visible. Install ground strap bolt and tighten to specification. Verify strap has no damage and connection is tight.
    Torque spec

    Ground Strap Bolts12 Nm (9 lb-ft)
12. 12

    Reconnect harness connectors
    Reconnect all harness connectors to fuse box in reverse order of removal. Reference photographs taken during disassembly. Push each connector firmly until locking tab clicks. Gently tug on each connector to verify it is fully seated and locked.
13. 13

    Reconnect terminal bolt connections
    Reconnect any remaining terminal bolt connections to the fuse box. Ensure terminals are properly oriented and seated. Tighten terminal bolts to specification in sequence from largest gauge wire to smallest.
    Torque spec

    Battery Terminal Bolts6 Nm (4 lb-ft)
14. 14

    Install fuses and relays
    Using your photographs and fuse box diagram, install all fuses and relays in their correct positions. Ensure each fuse and relay is fully seated. Replace any blown fuses identified during removal. Double-check all positions before proceeding.
    ⚠Installing fuses or relays in incorrect positions can cause electrical system damage or component failure
15. 15

    Reconnect battery and test
    Reconnect negative battery terminal and tighten to specification. Turn ignition to ON position without starting engine. Check that all warning lights illuminate normally on instrument cluster. Start engine and verify normal operation. Test all electrical systems including lights, windows, wipers, and accessories.
    Torque spec

    Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. Reinstall fuse box cover and secure with retaining clips
2. Verify all connectors are fully seated and locked
3. Check that no tools or parts are left in engine bay
4. Ensure all wiring is properly routed and secured with original clips
5. Verify battery terminals are tight and corrosion-free

Verification

• Turn ignition to ON position and verify no warning lights remain illuminated abnormally
• Start engine and confirm normal starting operation
• Test all major electrical systems: headlights, turn signals, brake lights, horn, wipers, windows, radio, climate control
• Verify instrument cluster displays all normal information
• Check for proper operation of power accessories including power locks and mirrors
• Use OBD-II scanner to check for any new diagnostic trouble codes
• Test drive vehicle and verify all electrical systems function normally under load
• Recheck all fuse box connections after test drive to ensure nothing has loosened

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