Replace the trunk/liftgate actuator (power trunk lock mechanism) on a 2016-2021 Honda Civic with 1.5L turbo engine to restore electronic trunk release functionality.

Warnings

Tools required

Parts

• Trunk/liftgate lock actuator × 1 — Honda OEM 74851-TBA-A01 or equivalent

Preparation

1. Park vehicle on level surface and engage parking brake
2. Open trunk and prop open fully
3. Disconnect negative battery terminal and wait 3 minutes to discharge any stored electrical energy
4. Gather all trim panel clips and fasteners in a container to prevent loss
5. Take photos of trunk latch area before disassembly for reference

Procedure

1. 1

   Disconnect the battery
   Using a 10mm socket, loosen the negative battery terminal bolt. Remove the negative cable from the battery post and secure it away from the terminal to prevent accidental reconnection during the repair.
   Torque spec

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

   Remove trunk interior trim panel
   From inside the trunk, locate the interior trim panel covering the trunk latch mechanism. Use trim removal tools to carefully pry out the plastic clips securing the panel. There are typically 4-6 push-type clips around the perimeter. Pull the panel away gently to access the latch assembly behind it.
3. 3

   Locate the trunk actuator assembly
   With the trim panel removed, identify the trunk latch actuator mounted to the trunk latch mechanism. It is a black plastic housing with an electrical connector and is located centrally on the latch assembly. Note the orientation and position of the actuator and its connection to the latch mechanism.
4. 4

   Disconnect the actuator electrical connector
   Locate the electrical connector attached to the trunk actuator. Press the release tab on the connector (typically on the top or side) and carefully pull the connector straight off the actuator. Do not pull on the wires. If the connector is stubborn, gently wiggle it while pulling to avoid breaking the locking tab.
   ⚠The connector locking tab is fragile plastic. Apply gentle pressure only to the designated release tab, not the connector body.
5. 5

   Remove actuator mounting fasteners
   Using a 10mm socket, remove the two or three bolts securing the actuator to the trunk latch mechanism. These are typically 10mm mounting bolts. Keep track of any washers or spacers that may be present. Support the actuator as you remove the final bolt to prevent it from falling.
   Torque spec

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

   Disconnect actuator linkage
   Carefully examine how the actuator rod or linkage connects to the trunk latch mechanism. On most Honda Civics, this is a plastic clip or pin connection. Gently compress or release the clip while pulling the actuator away from the latch to separate the mechanical linkage. Note the exact position and orientation for reinstallation.
7. 7

   Remove the old actuator
   Once the bolts and linkage are disconnected, remove the old actuator from the trunk latch assembly. Inspect the mounting area for any debris, corrosion, or damage. Clean the mounting surface with a clean rag if necessary.
8. 8

   Install the new actuator
   Position the new actuator in the same orientation as the old unit. First, connect the mechanical linkage rod to the latch mechanism, ensuring the clip or pin snaps fully into place. Verify the linkage moves freely without binding. Align the actuator mounting holes with the latch mechanism.
9. 9

   Install actuator mounting bolts
   Insert the mounting bolts through the actuator and into the latch mechanism. Hand-tighten all bolts first to ensure proper alignment. Using a torque wrench, tighten the mounting bolts to 26 Nm (19 lb-ft) in a cross pattern if multiple bolts are present. Verify the actuator is secure and does not move.
   Torque spec

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

    Reconnect electrical connector
    Push the electrical connector onto the new actuator until you hear or feel a distinct click, indicating the locking tab has engaged. Gently tug on the connector to verify it is fully locked in place. Ensure no wires are pinched or under tension.
11. 11

    Reconnect battery and perform initial test
    Reconnect the negative battery terminal and tighten the terminal bolt to 6.0 Nm (4.0 lb-ft). Do not overtighten. Before reinstalling trim, test the trunk release function using the key fob, interior button, and trunk handle to ensure the actuator operates correctly. Listen for proper motor operation without grinding or clicking noises.
    ⚠Ensure you have a way to exit the trunk or have assistance before testing. Do not test with the trunk fully closed if you are inside.
    Torque spec

    Battery Terminal Bolts6 Nm (4 lb-ft)
12. 12

    Reinstall trunk trim panel
    Once operation is verified, align the interior trim panel with the mounting locations. Press firmly on each clip location until all clips are fully seated and the panel is secure. Ensure all edges are flush and no clips are misaligned.

Reassembly

1. Verify all electrical connectors are fully engaged with audible clicks
2. Ensure no wires are pinched between the actuator and latch mechanism
3. Confirm all trim panel clips are fully seated and panel is secure
4. Check that no tools or parts were left in the trunk latch area

Verification

• Test trunk release from all methods: key fob, interior trunk release button, and exterior trunk handle
• Verify trunk locks properly when commanded via key fob or door lock button
• Listen for smooth actuator motor operation without grinding, clicking, or hesitation
• Confirm trunk light operates correctly when trunk is opened
• Test emergency trunk release from inside to ensure it still functions properly
• If equipped, verify trunk kick sensor operation (walk up with key fob and kick foot under bumper)
• Reset power window auto-up/down if necessary: with ignition on, hold window switch up until fully closed, continue holding for 2 seconds

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