This procedure covers the installation of an aftermarket subwoofer in a 2015-2020 Ford F-150, including wiring, mounting, and integration with the factory audio system.

Warnings

Tools required

Parts

• Subwoofer (aftermarket) × 1 — Customer supplied
• Amplifier (if not powered subwoofer) × 1 — Customer supplied
• Wiring kit with fuse holder × 1 — Minimum 8 AWG for typical installation
• Line output converter (if tapping speaker wires) × 1 — LOC-compatible with factory system
• Mounting hardware × 1 — Dependent on subwoofer box type
• Ground ring terminal × 1 — Appropriate for wire gauge

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery terminal and wait 2 minutes for airbag system to discharge
3. Determine mounting location for subwoofer (typically behind rear seat or in bed)
4. Plan wire routing from battery through firewall or along existing harness paths
5. Identify amplifier mounting location if using separate amplifier
6. Verify all components are compatible and wire kit is appropriate gauge for amplifier power requirements

Procedure

1. 1

   Remove rear seat bottom cushion
   For crew cab models, lift front edge of rear seat bottom cushion firmly upward to disengage retention clips. Remove cushion from cabin to access mounting area and allow wire routing. For under-seat subwoofer installations, verify clearance before proceeding.
2. 2

   Route power wire from battery
   Run power wire from battery positive terminal through existing firewall grommet (typically on driver side near brake booster) or create new sealed penetration. Use rubber grommet to protect wire insulation. Route wire along existing harness paths under carpet on driver side, securing with zip ties every 12 inches. Keep power wire away from ECM and other sensitive electronics.
3. 3

   Install inline fuse holder
   Install inline fuse holder on power wire within 18 inches of battery positive terminal. Use fuse rating appropriate for amplifier current draw (typically 40-60A for most applications). Do not insert fuse until final connections are verified. Secure fuse holder to prevent movement.
4. 4

   Establish ground connection
   Locate suitable ground point on chassis or body near amplifier location. Remove paint and debris from ground contact area using wire brush or sandpaper to ensure bare metal contact. Attach ground ring terminal to power wire and secure to chassis ground point using existing bolt or self-tapping screw. Apply dielectric grease to connection.
   ⚠Ground must be on bare metal with clean contact - poor ground causes overheating and audio noise
   Torque spec

   Ground Bolt16 Nm (12 lb-ft)
5. 5

   Locate and tap audio signal source
   For factory systems without dedicated subwoofer output, identify rear speaker wires at rear of cabin or behind head unit. Use multimeter to verify speaker polarity. Connect line output converter (LOC) to rear speaker wires using appropriate tap connectors. For systems with factory subwoofer output or aftermarket head unit with RCA outputs, connect RCA cables directly to amplifier input. Route signal wires along passenger side away from power wire to minimize noise.
6. 6

   Mount amplifier
   Secure amplifier to mounting surface using appropriate hardware. Common locations include under rear seat, behind seat back, or on bed wall for SuperCrew models. Ensure adequate ventilation around amplifier heat sink. Do not mount amplifier to plastic trim panels. Use vibration-isolating hardware if available. Verify amplifier controls are accessible for tuning.
   ℹ️Amplifier requires minimum 2 inches clearance on sides with heat sink for proper cooling
   Torque spec

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

   Position and secure subwoofer enclosure
   Place subwoofer enclosure in predetermined location. For under-seat installations, verify clearance for seat movement and occupant safety. Secure enclosure using mounting brackets, bolts, or straps to prevent movement during vehicle operation. Ensure speaker wire terminals are accessible. For bed-mounted installations, use bed tie-down points or through-bolted mounting.
   Torque spec

   Module Mounting Bolts8 Nm (6 lb-ft)
8. 8

   Connect power and ground to amplifier
   Connect power wire to amplifier power terminal and tighten terminal screw securely. Connect ground wire to amplifier ground terminal. Verify all connections are tight and wire insulation is not damaged. Route wires to avoid pinch points and moving components.
   Torque spec

   Battery Terminal Bolts6 Nm (4 lb-ft)
9. 9

   Connect signal and remote wires
   Connect RCA cables or LOC output to amplifier input terminals. Connect remote turn-on wire to amplifier remote terminal. Remote wire should tap into head unit remote output (blue wire) or use signal-sensing feature if LOC is equipped with remote output. Secure all connections and dress wires neatly.
10. 10

    Connect speaker wires to subwoofer
    Run speaker wire from amplifier output terminals to subwoofer. Observe proper polarity (positive to positive, negative to negative). Strip wire ends cleanly and make secure connections at both amplifier and subwoofer terminals. For dual voice coil subwoofers, wire according to desired impedance configuration per manufacturer specifications.
11. 11

    Reconnect battery and initial testing
    Reconnect negative battery terminal. Insert fuse into inline fuse holder. Turn ignition to accessory position and verify amplifier powers on (indicator LED illuminates). Check for blown fuses or unusual odors indicating short circuit. If issues occur, immediately disconnect battery and troubleshoot.
    Torque spec

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

    Adjust amplifier settings
    Set amplifier gain to minimum. Turn on audio system and play familiar music with good bass content. Gradually increase gain until desired output is achieved without distortion. Adjust low-pass crossover to blend with factory speakers (typically 80-120 Hz for most systems). Adjust bass boost sparingly if equipped. Set phase switch if applicable. Fine-tune settings while listening to various music types.

Reassembly

1. Reinstall rear seat cushion by aligning clips and pressing down firmly until seated
2. Secure all loose wiring with zip ties and wire loom to prevent rattles
3. Verify all panels and trim pieces removed during installation are reinstalled properly
4. Check that no wires are pinched or contacting sharp edges
5. Ensure ground connections remain tight and corrosion-free

Verification

• Test subwoofer at various volume levels to verify proper operation without distortion
• Check for amplifier overheat protection engagement during extended use
• Verify no electrical noise or whining through speakers when engine RPM changes
• Confirm amplifier turns on and off with ignition (no battery drain when vehicle is off)
• Test across multiple audio sources (radio, Bluetooth, USB) to ensure consistent performance
• Inspect all connections after 100 miles of driving to verify nothing has loosened
• Verify subwoofer enclosure remains secure with no movement or vibration against vehicle body

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