2010-2024 4Runner Alpine Plug & Play 5-Channel Amplifier Kit Installation Guide

🛠️Parts Included:

• Alpine S2-A55V 5-Channel Amplifier
• AudX 4Runner Amplifier Mounting Bracket
• AudX T-Harness
• AudX Main harness
• RCA adapters
• Trail Grid Pro Amplifier Install Kit
• 10 Zip Ties
• 10mm Ground Bolt

🛠️Tools Needed:

• Panel removal tool
• 10mm socket
• 12mm socket
• 14mm socket
• Ratchet wrench
• Socket extension
• Phillips head screwdriver
• Zip ties
• Razor knife
• Wire fish

Step 1: Disassembling the Dash

• Remove the Side Panels:
  • Pull straight out on both left and right side panels to remove them.
• Remove the HVAC Control Panel:
  • Gently pull out the HVAC control panel.
  • Disconnect the HVAC wiring harness by unplugging the connector in the back.
  • Use a small flathead screwdriver or panel tool to release the retaining clip securing the connection.
• Remove the Head Unit Mounting Bolts:
  • Locate the four 10mm bolts underneath the head unit.
  • Remove them using a 10mm socket wrench or an impact gun.
  • ⚠️Pro Tip: Place the bolts in the cup holder to avoid losing them.
• Remove the Factory Head Unit:
  • Gently pull out one side of the head unit to loosen it.
    
  • Move to the other side and repeat the process.
    
  • Once loosened, grab the center and pull straight out to remove the head unit.
  • Place a microfiber towel over the shift knob to prevent scratches or damage.
• Disconnect All Wiring Connections:
  • Unplug all wiring harnesses from the back of the head unit one at a time.
  • Some connectors may be difficult to remove—use a small flathead screwdriver to press the release tab and pull out.
    
• Remove the Bracket & Final Connection:
  • Identify the bracket on the back of the head unit, which is secured by a connector and tape.
  • Either disconnect the connector or cut the tape to fully detach the bracket.

Step 2: Disassembling Your 4Runner

• Remove the Center Console:
  • If equipped with a manual 4WD gear shifter, twist the handle counterclockwise to remove it.
  • Twist the gear shifter handle counterclockwise to remove it.
  • Lift up on the shifter panel to detach it.
  • Disconnect any wire connections before fully removing the panel.
  • Use a pry tool to lift and remove the lower trim panel.

• Remove the Trim Panel with 12V Outlet and USB:
  • Remove the two 10mm bolts securing the trim panel.
  • Pull the panel straight out to release the retaining tabs.
  • Disconnect any connectors before removing the panel completely.

• • Pull the panel straight out to release the retaining tabs.
  • Disconnect any connectors before removing the panel completely.
• Remove the Passenger Front Seat:
  • Lift the passenger front door sill plate straight up to remove it.
  • Remove the plastic nut securing the passenger-side kick panel.
  • Pull the kick panel straight out to detach it.
  • Remove the plastic covers from the front seat bolt brackets.
  • Use a 14mm socket to remove the front seat bolts.
  • Move the seat into the forward position.
  • Remove the plastic covers from the rear seat brackets.
  • Use a 14mm socket to remove the rear seat bolts.
  • Move the seat to the middle position and lean it back to access the underside.
  • Disconnect all wiring connectors by pressing the release tabs.
  • Carefully remove the seat from the vehicle.

Step 3: Routing the Power Wire

• Prepare the Power Wire:
  • Open the hood and secure it in place.
  • Locate the power wire with the inline fuse included in your kit.
  • Connect the short power wire to one side of the inline fuse by securing the wire ferrule using a 3mm Allen key.
  • Connect one end of the longer power wire to the other side of the inline fuse the same way.
• Route the Power Wire:
  • Place the ring terminal near the positive battery terminal (do not connect it yet).
  • Route the power wire along the driver’s side fender, across the firewall, and toward the passenger-side firewall grommet.
• Pass Through the Firewall:
  • Use a utility knife to carefully cut an "X" in the firewall grommet to allow the power wire to pass through.
    
    ⚠️ Note: Many Toyota firewall grommets have both an exterior and interior membrane—cut through both.
    ⚠️ Be careful not to damage any vehicle wiring while cutting.
    
    
  • Use a wire fish tool if necessary to guide the ferrule end of the power wire into the cab.
  • Once the wire is through the firewall, pull the slack into the passenger-side floorboard.
• Run the Power Wire to the Amplifier:
  • Route the wire down the passenger-side kick panel and through the factory wire channel.
  • Run the wire under the carpet to the power side of the amplifier.
  • Use the provided zip ties to secure any loose wiring in the engine bay.

Step 4: Routing the Main Harness

• Route the Main Harness:
  • Position the main harness under the front passenger seat.
  • Start with the T-harness end and begin routing it toward the head unit.
  • Run the harness under the carpet, directing it toward the gear shifter.
  • Continue routing the harness through the transmission tunnel area, moving toward the front of the vehicle.

• • Remove the radio to access the connection points.
  • Guide the T-harness up inside the dash, routing it towards the main radio connections.

Step 5: Making Connections to Your Head Unit

For 2010–2019 Models

Factory Head Unit:

• Disconnect the 10-pin and 6-pin and from the back of the head unit.
• Plug the male end of the AudX T-Harness into the 10-pin and 6-pin ports on the head unit.
• Attach the vehicle’s 10-pin and 6-pin connectors to the female end of the AudX T-Harness.
  
• ⚠️ (Optional) If grounding the harness, secure the black wire with the small ring terminal to a clean metal-to-metal ground location.

Aftermarket Head Unit:

• Disconnect the 10-pin and 6-pin connectors from the back of the head unit.
• Connect the male end of the AudX T-Harness to the 10-pin and 6-pin ports on the head unit.
• Attach the vehicle’s 10-pin and 6-pin connectors to the female end of the AudX T-Harness.
• Connect RCA cables to the RCA outputs on the aftermarket radio.

For 2020–2024 Models

Factory Head Unit:

• Disconnect the 10-pin and AM/FM antenna connector from the back of the head unit.
• Connect the male end of the AudX T-Harness to the 10-pin and AM/FM antenna port on the head unit.
• Attach the vehicle’s 10-pin and AM/FM antenna connector to the female end of the AudX T-Harness.
• If you choose to ground the harness, secure the black wire with small ring terminal to ground location, ensuring it is a good metal to metal contact. 

Aftermarket Head Unit:

• Disconnect the 10-pin and AM/FM antenna connector from the back of the head unit.
• Connect the male end of the AudX T-Harness to the 10-pin and AM/FM antenna location on the head unit.
• Attach the vehicle’s 10-pin and AM/FM antenna connector to the female end of the AudX T-Harness.
• Connect RCA cables to the RCA outputs on the aftermarket radio:
  • Front Speakers:
    White → White
    Grey → Red
  • Rear Speakers:
    Green → White
    Purple → Red
  • Subwoofer:
    Orange → White
    Brown → Red
• ⚠️ (Optional) If grounding the harness, secure the black wire with the small ring terminal to a clean metal-to-metal ground location.

Step 6: Reinstall Your Head Unit

• Reconnect and Reposition:
  • Ensure that all previously disconnected wiring connections are securely reattached.
  • Carefully position the head unit back into the dash.
  • Fasten the head unit using the four factory 10mm bolts.

⚠️ Important: Do not fully reassemble the dash at this point—functionality should be tested before completing the installation.

Step 7: Connecting the Ground Wire

• Secure the Ground Connection:
  • Use the provided ground wire to connect the ring terminal to the factory ground point located under the passenger seat.
  • If a factory ground bolt is not present, use the included bolt to secure the ring terminal to the pre-threaded hole under the seat.

Step 8: Connecting the Bass Control Knob

• Mount and Connect the Bass Knob:
  • Attach the bass control knob in your preferred location using the included Velcro, or install it into one of our Switch Blank Mounts.
  • Route the control knob wire from the main harness and plug the 3.5mm headphone jack into the bass control knob.
  • Use zip ties to secure any excess or loose wiring.

Step 9: Mount Amplifier to Amplifier Mounting Bracket

• Install the Amplifier:
  • Place the amplifier mounting bracket with the AudX label facing up.
  • Align the amplifier with the pre-drilled holes on the mounting bracket, orienting it so the RCA ports face the passenger door.
  • Insert one bolt up through the bottom of the amplifier mounting bracket, then through the amplifier’s mounting hole.
  • Place a flat washer, followed by a split washer, and secure it with a nut.
  • Use a 9/32" wrench and a Phillips head screwdriver to tighten the hardware.
    ⚠️ Do not overtighten.

Step 10: Making Connections To Amplifier

• RCA Input Harness:
  • Use a Phillips-head screwdriver to remove one screw from the amplifier's control faceplate.
    Place the ring terminal from the ground wire over the screw.
    Re-secure the screw to fasten the ground.
• Connect the RCA's:
  • CH-1 L - FL White
  • CH-2 R - FL Grey
  • CH-3 L - RL Green
  • CH-4 R - RR Purple
  • Sub L - SL Orange
  • Sub R - SR Brown
• Connect the Remote Wire:
  • Insert the remote wire ferrule into the REM input on the amplifier.
  • Tighten the screw using a 2mm Allen wrench.
  • Connect the harness to the 4-pin connector on the main harness.
• Wire Ferrule Harness
  • Connect the harness to the 8-Pin connector on main harness. 
• Make the following speaker connections:
  • Rear speaker leads on the bottom row: 
    • CH-1 - White/Black Stripe
    • CH-2 - Grey/Black Stripe
    • CH-3 - Green/Black Stripe
  • CH-4 - Purple/Black Stripe
• Front speaker leads on the top row:
  • • CH-1 + White
    • CH-2 + Grey
    • CH-3 + Green
    • CH-4 + Purple
• Subwoofer Wire
  • Connect wire ferrule ends to amplifier:
    • Sub - Black Wire
    • Sub + Red Wire
• Connect Ground and Power Wires:
  • Connect the provided black ground wire to the amplifier and secure it using a 2mm Allen wrench.
  • Connect the power wire to the amplifier and secure it with a 2mm Allen wrench.

Step 11: Route Subwoofer Wire

• Route the Wire to the Rear Cargo Area:
  • Remove the rear door sill by pulling straight up.
  • Route the subwoofer wire through the factory wiring channel toward the rear cargo area.
  • Press the subwoofer wire under the interior plastic panels and continue routing it to the cargo area.
• Connect to the Subwoofer:
  • Connect the yellow wire to the positive (+) terminal.
  • Connect the black wire to the negative (–) terminal.

Step 12: Connect Power To Battery

• Connect the Power Wire:
  • Locate the short length of power wire with the pre-connected ring terminal.
  • Connect the ring terminal securely to the positive battery terminal.

Step 13: Test System

• Power On and Verify Functionality:
  • Turn on your vehicle and test the audio system.
  • Confirm that both the radio and amplifier are functioning properly.

🛠️Troubleshooting Tip:
If the head unit powers on but you hear no sound, double-check that the remote turn-on wire is properly connected.

Step 14: Tune The Amplifier

• Set Initial Amplifier Settings:
  • On your Alpine S2-A55V amplifier, set the following:
    • Fader: ON
    • Input Level: LO
    • Sub Input: SUB
• Adjust Gain Levels:
  • Choose a song that plays continuously for a few minutes.
  • Turn the volume on your head unit to about 75% of the maximum volume.
  • Using a small flathead screwdriver, adjust the Amp 1 gain (Front Speakers) to your desired sound level.
  • Repeat the process for the Amp 2 gain (Rear Speakers).
  • Adjust the Sub gain last to set your desired bass level.
    • ⚠️ Warning: If you hear distortion, clipping, or audio cutting out, the gain is set too high—reduce accordingly.
• Final Adjustments:
  • Use your head unit’s built-in EQ settings to fine-tune the overall sound to your personal preference.

Step 15: Reassembly

• Reinstall the Seat and Mounting Bracket:
  • Once you’ve confirmed the system is functioning properly and your amplifier gains are set, begin reassembly.
  • Line up the mounting holes on the amplifier mounting bracket with the rear seat bolt holes.
  • Place the passenger seat back into position, aligning the rear seat mounts with the amplifier bracket.
  • Start all four 14mm seat bolts by hand, then tighten them using a 14mm socket.
  • When installed correctly, the amplifier bracket should be sandwiched between the seat mounts and the floor, with the bolts running through the bracket tabs.
• Finish Reassembling the Vehicle:
  • Reinstall all remaining components, including the rest of the seat, center console, and dash panels.

Congratulations on installing your new Alpine 5 Channel Amplifier Plug & Play Kit!