Horn Relay

This procedure involves replacing the horn relay located in the under-hood fuse/relay box on the 2016-2021 Honda Civic 1.5L Turbo.

Warnings

Tools required

Parts

• Horn relay × 1 — Use OEM Honda relay or equivalent

Preparation

1. Park vehicle on level surface and turn off ignition
2. Allow engine to cool if recently operated
3. Locate the under-hood fuse/relay box on the driver's side of the engine bay
4. Have replacement relay ready and verify correct part number by comparing with old relay

Procedure

1. 1

   Disconnect battery negative terminal
   Using a 10mm socket, loosen the negative battery terminal bolt and remove the negative cable from the battery post. Secure the cable away from the battery to prevent accidental reconnection.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)
2. 2

   Access the under-hood fuse/relay box
   Locate the under-hood fuse/relay box on the driver's side near the firewall. Release the locking tabs on the cover by pressing or pulling them outward, then lift the cover off the fuse box. The relay diagram is typically printed on the underside of the cover.
3. 3

   Identify the horn relay
   Reference the relay diagram on the fuse box cover to identify the horn relay location. The horn relay is typically labeled on the diagram and may be marked as 'HORN' or with a specific relay number. Verify the relay position before removal.
4. 4

   Remove the old horn relay
   Using a relay puller or needle-nose pliers, grip the horn relay firmly and pull straight up with steady pressure to extract it from the socket. Avoid rocking or twisting motion to prevent damage to the socket terminals. Inspect the relay terminals and socket for corrosion or damage.
5. 5

   Install the new horn relay
   Align the new horn relay with the socket, ensuring the relay pins match the socket configuration. The relay will only fit in one orientation. Press the relay firmly into the socket until it is fully seated and flush with surrounding relays. Verify the relay is secure by gently attempting to pull it upward.
6. 6

   Reinstall fuse box cover
   Position the fuse box cover back onto the fuse/relay box, ensuring all edges are properly aligned. Press down firmly on the cover until all locking tabs click into place and the cover is secure.
7. 7

   Reconnect battery negative terminal
   Place the negative battery cable back onto the negative battery post. Tighten the terminal bolt to specification using a 10mm socket. Ensure the connection is secure but do not overtighten.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)

Reassembly

1. Ensure fuse box cover is properly secured with all tabs engaged
2. Verify battery terminal connection is tight and corrosion-free
3. Reset clock and radio presets as needed after battery reconnection

Verification

• Turn ignition to ON position without starting engine
• Press the horn button on the steering wheel and verify horn sounds properly
• Test horn with engine running to confirm operation under load
• If horn does not work, verify relay is fully seated and check fuse condition
• Perform power window auto-up/down recalibration if necessary by fully lowering then raising each window and holding the switch for 2 seconds

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