How to Install a Car Amplifier
Learn to safely wire and mount a car amplifier, including power routing through the firewall, solid chassis grounding, and running signal cables without interference.
- Read the tools, materials, safety notes, and steps below for free.
- Tap Start Camera Coach when you want hands-free voice help.
- Allow camera and microphone. Point your phone at the work; the coach watches your progress and tells you the next step.
🧰 Required Tools & Equipment
- ✓ Socket and ratchet set
- ✓ Wire stripper and crimper
- ✓ Plastic trim panel removal tool
- ✓ Cordless drill and drill bits
- ✓ Digital multimeter
📦 Materials & Supplies
- ✓ Amplifier wiring kit (power, ground, RCA, remote turn-on wire)
- ✓ Inline fuse holder with correct amperage fuse
- ✓ Ring terminals and spade connectors
- ✓ Nylon zip ties
- ✓ Coarse sandpaper or wire brush
- ✓ Self-tapping metal screws
⚠️ Safety Checkpoints & Warnings
- • Always disconnect the vehicle's negative battery terminal before touching any electrical wiring.
- • Keep the main inline fuse out of its holder until all wiring connections are completely finished.
- • Protect power cables running through metal holes with rubber grommets to prevent short circuits and vehicle fires.
📋 Step-by-Step Guide (5 Steps)
Disconnect Battery and Mount Amplifier
Use a socket wrench to disconnect the negative (-) battery cable and secure it away from the terminal. Position the amplifier in your chosen location (trunk or under seat) ensuring adequate airflow around cooling fins. Secure the amplifier to the vehicle floorboard using short sheet metal screws, checking underneath for fuel lines or brake lines first.
- • Negative battery terminal is physically detached and isolated.
- • Amplifier is bolted down firmly and does not rock when pushed.
- • Drilling through the floorpan into hidden gas lines, wiring harnesses, or brake lines.
- • Mounting upside down or in an enclosed space without airflow.
Install Inline Fuse and Route Power Wire
Mount the inline fuse holder within 18 inches of the battery terminal using a screw or bracket, leaving the fuse out for now. Crimp a ring terminal onto one end of the main power wire and attach it to the positive battery terminal post. Run the long power wire through an existing firewall grommet into the vehicle interior.
- • Fuse holder mounted rigidly near the battery with no fuse inserted inside.
- • Power wire passes smoothly through a rubber grommet in the firewall.
- • Placing the fuse inside the holder before all wiring is finished.
- • Running bare wire through raw, sharp firewall metal without a protective rubber grommet.
Establish Chassis Ground Connection
Find a clean, unpainted factory bolt or bare metal spot on the vehicle chassis within 18 to 36 inches of the amplifier. Scrape away all paint, primer, and rust down to shiny bare metal using coarse sandpaper. Crimp a heavy-duty ring terminal to the ground wire, bolt it firmly against the bare metal, and check continuity to ground with a multimeter.
- • A nickel-sized circle of shiny, bare, paint-free metal under the ground lug.
- • Ground wire firmly secured with a bolt, lock washer, and no play.
- • Bolting the ground wire over painted or rusted metal, causing ground loops and amplifier shutdown.
- • Using a ground wire longer than 3 feet.
Route RCA and Remote Turn-On Wires
Pry up door sill trim panels using a plastic trim tool. Route the heavy power cable down one side of the vehicle and the RCA signal cables along the opposite side to prevent induced electrical hum. Connect the blue remote turn-on lead and RCA cables to the rear of the head unit and run them back to the amplifier alongside the RCA path.
- • Power wire tucked entirely along one side sill (e.g., driver side).
- • RCA and remote wires tucked along the opposite side sill (e.g., passenger side).
- • Running power cables parallel and right next to RCA cables, which introduces alternator whine into speakers.
- • Crushing cables underneath carpet clip attachment points.
Connect Wires to Amplifier and Insert Fuse
Strip 1/2 inch of insulation from power, ground, and remote wires, insert them into their respective amp terminal blocks (+12V, GND, REM), and tighten the set screws firmly. Plug the RCA patch cables into the line inputs and attach the speaker output wires observing correct polarity (+/-). Finally, reconnect the vehicle negative battery terminal and insert the inline power fuse under the hood.
- • All amp terminal screws tight with zero stray copper strands exposed outside ports.
- • Inline fuse seated firmly in the engine bay fuse holder with cover closed.
- • Amplifier power LED lights up solid green/blue when car ignition and stereo are turned on.
- • Swapping the +12V power and GND wires, blowing internal amplifier fuses immediately.
- • Loose copper strands bridging the gap between positive and ground terminals.
Credit: inspired by an original tutorial by CRUTCHFIELD — watch the original on YouTube.
Don’t have everything?
- No Plastic trim panel removal tool? Flathead screwdriver taped with electrical tape on the metal tip
- No Wire stripper and crimper? Utility knife for careful stripping and linesman pliers for crimping