Welcome to the installation guide for your 2014–2021 Toyota Tundra Alpine Plug & Play 4-Channel Amp & Powered Subwoofer Kit from Trail Grid Pro! This step-by-step guide is designed to make the installation process as smooth as possible, whether you're a seasoned DIYer or tackling your first head unit upgrade.
In this guide, you’ll find:
- 📢 Important Updates: The written guide includes the latest updates and adjustments that may not be shown in the video, ensuring you have the most up-to-date instructions for a flawless installation.
- 🎥 Installation Videos: Visual instructions to help you through the process, including a detailed microphone install.
- 🛠️ Parts Included and Tools Needed: A quick list of everything you'll need to get started.
- 📝Step-by-Step Instructions: Clear, easy-to-follow directions from disassembling your dash to securing the new Sony head unit.
- ⚠️ Special Notes: Important information and considerations for your installation.
- 🛠️ Common Troubleshooting Solutions: Quick and effective fixes for common installation and performance issues.
Table of Contents
- Important Updates
- Installation Video
- Parts Included
- Tools Needed
- Step 1: Preparing the Subwoofer
- Step 2: Installing the Left Bracket & Amplifier
- Step 3: Installing the Right Bracket
- Step 4: Disassembling the Dash
- Step 5: Disassembling Your Tundra
- Step 6: Routing the Power Wire (For Non-Amplified Trucks Only)
- Step 7: Routing the Main Harness
- Step 8: Making Connections to Your Head Unit
- Step 9: Reinstall Your Head Unit
- Step 10: Connecting the Ground Wire
- Step 11: Connecting the Bass Control Knob
- Step 12: Installing the Subwoofer and Amplifier
- Step 13: Connecting the Power Wire to the Battery
- Step 14: Testing System Functionality
- Step 15: Reassembling Your Tundra
- Common Troubleshooting Solutions
📢 Important Updates & Notes
Update (February 2025): To ensure your items arrive safely, we’ve updated the kit assembly process. Please follow Steps 1, 2, and 3 to complete the final assembly of your Alpine 4-Channel Amplifier and Subwoofer Kit from Trail Grid Pro.
🎥Installation Video
🛠️Parts Included:
- Amplifier assembly:
- Vehicle specific mounting bracket
- Alpine PWE-S8 powered subwoofer
- Alpine KTP-445U 4 channel amplifier
- T-Harness
- Main harness
- Amplified Non-JBL Bypass Harness (For Tundra's equipped with the non-branded amplifier)
- 4x RCA adapters
- Power Cable
- 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-by-Step Instructions
Step 1: Preparing the Subwoofer
- Take the subwoofer out of the packaging.
- Place it on a flat surface with the speaker grille facing downward.
- Position the subwoofer so that the Alpine sticker and controls are visible and facing you.
Step 2: Installing the Left Bracket and Amplifier
- Take the bracket out of the packaging.
- Place it on a flat surface as shown in the image below.
- Take the amplifier out of the packaging.
- Position it onto the left bracket.
- Make sure the gain controls are facing you.
- Secure the amplifier to the bracket using the screws provided in the “Amplifier Mounting Screws” bag.
- Flip the bracket over and position it on the left side of the subwoofer.
- Secure the left bracket using the screws provided in the “Bracket Mounting Screws” bag.
- For each assembly, insert one bolt, followed by a split washer, and then a flat washer.
- Repeat this process eight times.
- Tighten the Phillips head bolts, but avoid over-tightening.
Step 3: Installing the Right Bracket
- Take the bracket out of the packaging and position it on the subwoofer as shown below.
- Secure the right bracket using the screws from the “Bracket Mounting Screws” bag.
- For each assembly, insert one bolt, followed by a split washer, and then a flat washer.
- Repeat this process eight times.
- Tighten the Phillips head bolts, but avoid over-tightening.
Step 4: Disassembling the Dash
- Remove the lower dash panel that contains the USB ports.
- Insert a panel removal tool into the gap between this panel and the HVAC panel. Once loosened, pull straight back to release the retaining clips.
- Pull the HVAC panel straight out using your hands.
- Disconnect the single plug from the back of the HVAC control panel.
- To remove the factory head unit:
- Use a 10mm socket and extension to remove the four 10mm bolts securing the bottom of the radio. Store them in the cup holder for safekeeping.
- Pull the head unit straight back to release the upper retaining clips.
- Disconnect all wiring connections from the back of the radio by pressing the tabs on each connector and unplugging them.
Step 5: Disassembling Your Tundra
Remove the center console:
- Twist the gear shifter handle counterclockwise to remove it.
- Open the center console.
- Lift up on the shifter panel to remove it.
- Disconnect any wire connections before fully removing.
- Pull straight out to release the retaining tabs.
- Disconnect any connectors before removing the panel completely.
Remove the passenger front seat:
- 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 6: Routing the Power Wire (For Non-Amplified Trucks Only)
If your truck is non-amplified use the following instructions:
- Lift straight up to remove the passenger front door sill plate.
- Remove the plastic nut securing the passenger side kick panel.
- Pull the kick panel out to remove it.
- Remove the panel under the dash.
Routing the Power Wire:
- Open the hood and secure it in place.
- Locate the spyder-wrapped power wire with an inline fuse (included in the kit).
- Start by placing the ring terminal near the positive battery terminal.
- Route the power wire along the driver’s side fender, across the firewall, and toward the passenger-side firewall grommet.
- Using a utility knife, carefully cut an "X" in the grommet to allow the power wire to pass through.
- ⚠️Note: Many Toyota firewall grommets have both an exterior and interior membrane—you will need to cut through both.
- Take extra care to avoid damaging any vehicle wiring while cutting.
- Use a wire fish tool if needed to guide the blue bullet connector end of the power wire into the cab.
- Once the power wire is through the firewall, pull the slack into the passenger-side floorboard.
- Secure any loose wiring in the engine bay using the provided zip ties.
Step 7: Routing the Main Harness
- Position the main harness under the front passenger seat.
- Locate the T-harness end and begin routing it toward the head unit.
- Guide the harness under the carpet, moving directly toward the gear shifter.
- Once the harness reaches the transmission tunnel, continue routing it toward the front of the vehicle.
- Remove the radio to access the necessary connections.
- Route the T-harness up through the inside of the dash toward the main radio connections.
Step 8: Making Connections to Your Head Unit
Making connections to your 2014-2019 head unit:
Factory Head Unit:
- Disconnect the 10-pin and 6-pin connectors from the back of the head unit.
- Connect the male end of the Alpine T-Harness to the 10-pin and 6-pin locations on the head unit.
- Connect the vehicle’s 10-pin and 6-pin connectors to the female end of the Alpine T-Harness.
Aftermarket Head Unit:
- Disconnect the 10-pin and 6-pin connectors from the back of the head unit.
- Connect the male end of the Alpine T-Harness to the 10-pin and 6-pin locations on the head unit.
- Attach the vehicle’s 10-pin and 6-pin connectors to the female end of the Alpine T-Harness.
- Connect RCA cables to the RCA outputs on the aftermarket radio.
- Front Speakers:
- White to White
- Grey to Red
- White to White
- Rear Speakers:
- White to White
- Red to Red
- Green to White
- Purple to Red
- White to White
Making connections to your 2020-2021 head unit:
Factory Head Unit:
- Disconnect the 10-pin connector from the back of the head unit.
- Connect the male end of the Alpine T-Harness to the 10-pin location on the head unit.
- Connect the vehicle’s 10-pin connector to the female end of the Alpine T-Harness.
Aftermarket Head Unit:
- Disconnect the 10-pin connector from the back of the head unit.
- Connect the male end of the Alpine T-Harness to the 10-pin location on the head unit.
- Attach the vehicle’s 10-pin connector to the female end of the Alpine T-Harness.
- Use the provided bullet connectors to connect the remote turn-on wire (Blue with White Stripe) to the aftermarket head unit.
- Connect RCA cables to the RCA outputs on the aftermarket radio:
- Front Speakers:
- White to White
- Grey to Red
- White to White
- Rear Speakers:
- Green to White
- Purple to Red
- Green to White
- Subwoofer:
- White to White
- Red to Red
- White to White
Step 9: Reinstall Your Head Unit
- Ensure that all previously disconnected connections are securely reattached.
- Position the head unit back into the dash and fasten it using the four factory 10mm bolts.
- Do not fully reassemble the dash yet—functionality should be tested before completing the installation.
Step 10: Connecting the Ground Wire
- Use the provided Alpine ground wire to connect the ring terminal to the factory ground located under the passenger seat.
- If a factory ground bolt is not present, secure the ring terminal using the provided bolt in the pre-threaded hole under the passenger seat.
Step 11: Connecting the Bass Control Knob
- If using the PSU kit with a factory head unit and want to adjust the bass, install the provided control knob.
- Attach the bass control knob in your preferred location using the included Velcro.
- Route the control knob wire to the subwoofer/amplifier assembly and plug the 3.5mm headphone jack into the subwoofer.
- Use zip ties to secure any excess or loose wiring.
Step 12: Installing the Subwoofer and Amplifier
- Position the subwoofer/amplifier assembly on the floor under the front passenger seat.
- The angled end of the brackets should face the front of the vehicle.
- When properly aligned, the bracket holes will match the factory seat bolt locations and locating pins.
Connecting the Alpine Main Harness to the Subwoofer and Amplifier For Non-Amplified Tundra:
- Connect the White 14-pin connector to the subwoofer.
- Connect the RCA cables from the main harness to the subwoofer:
- Red to Red
- White to White
- Connect the Black 16-pin connector to the amplifier.
- Connect the Black 10-pin connector to the amplifier.
- If the power wire was routed to the battery, connect the bullet connector from the power wire to the yellow wire on the main harness.
For Amplified Non-JBL Tundra:
- Connect the White 14-pin connector to the subwoofer.
- Connect the RCA cables from the main harness to the subwoofer:
- Red to Red
- White to White
- Connect the Black 16-pin connector to the amplifier.
- Connect the Black 10-pin connector to the amplifier.
- Connect the bullet connector from the bypass harness to the yellow wire on the Alpine main harness.
- Connect the 12-pin connector from the bypass harness to the 12-pin connector removed from the factory amplifier.
- Connect the 10-pin connector from the bypass harness to the 12-pin connector removed from the factory amplifier.
- Use the provided zip ties to secure any loose or excess wiring.
Step 13: Connecting the Power Wire to the Battery
- Use a 10mm or 12mm wrench to remove the nut from the positive battery terminal.
- Place the ring terminal from the Alpine power wire onto the positive terminal and secure it with the factory nut.
- ⚠️Note: A small spark when connecting the ring terminal is normal and expected.
Step 14: Testing System Functionality
- Power on your vehicle and verify that all components are functioning properly.
- Play a song that will run continuously for a few minutes.
- Check the Balance/Fade settings to ensure all speakers are playing correctly.
Below is the recommended amplifier setting for use with a Factory Head Unit:
Below is the recommended amplifier setting for use with an Aftermarket Head Unit:
Once you have confirmed that your system is working and the gains are adjusted to your preference, reassemble your vehicle and enjoy your newly amplified system!
Step 15: Reassembling Your Tundra
Reinstalling the Front Passenger Seat:
- Ensure the amplifier and subwoofer settings are set to your preference before reinstalling the seat.
- Secure any loose wires and align the subwoofer/amplifier brackets with the mounting holes in the floorboard.
- Carefully position the seat back in place.
- Reconnect any wiring harnesses that were disconnected during disassembly.
- Hand-tighten the four 14mm bolts that secure the seat.
- Use a 14mm socket to fully tighten the seat bolts.
- Reattach the plastic covers over the seat bolts.
Reinstalling Trim Panels and Center Console:
- Replace the kick panel at the bottom of the A-pillar and secure the plastic retention nut.
- Press the door sill panel back into place.
- Install the plastic trim panel below the glove box.
- Replace the panel under the dash.
- Reconnect any wiring connectors to the center console trim.
- Position the console trim and press it down to secure it.
- Reinstall the lower trim panel containing the 12V outlet and USB.
- Secure it with two 10mm bolts.
Reinstalling the Radio and Center Dash Trim:
- Fully tighten the four 10mm bolts securing the head unit.
- Reconnect the HVAC panel wiring and press it into place.
- Reinstall the center console trim and screw the shift knob back on.
Congratulations on installing your new Alpine 4 Channel Amplifier and Powered Subwoofer kit!
🛠️ Common Troubleshooting Solutions: Experiencing issues with your installation? Try these steps before reaching out for support.
1. Check the Connections Behind the Head Unit
If you have a factory head unit:
- Ensure the main vehicle connectors are fully seated.
- Verify the remote wire from the amplifier harness is properly connected to the radio using either a T-tap or T-harness.
- If using a T-tap, confirm that the connection is solid. A good connection will be indicated by the blue light on the subwoofer illuminating.
If you have an aftermarket head unit:
- Ensure the main vehicle connectors are fully seated.
- Verify that the RCA connections are fully plugged in.
- Check that the remote wire from the amplifier harness is connected to the radio harness.
- Make sure the subwoofer output is turned on in the head unit settings menu.
2. Check the Alpine Amplifier Settings
- Confirm that the front and rear gain settings are turned low/off.
- Double-check the dip switches on the amplifier—the recommended settings can be found in the installation guide.
3. Check the Subwoofer Settings
- Make sure the input selector is set to "Remote".
- Verify that the blue indicator light is on.
- Check that the gain and crossover dials are set to low/off.
- Ensure the RCA adapter is connected from the amplifier harness to the RCA inputs on the subwoofer.
If the RCA adapter is not connected, follow these steps:
- Locate the red 4 pin connector on the main harness near the subwoofer.
- Disconnect the male and female ends of the red 4 pin connector.
- Find the RCA adapter in the "Extra Parts" bag.
- Attach the male 4-Pin connector from the RCA adapter to the female red 4 pin connector.
- Connect the RCA's to the RCA inputs on the subwoofer.
- Play music and adjust the subwoofer gain to your preferred level.
4. Optimizing Sound Quality and Tuning Your System
Once you’ve confirmed all connections and ensured that the amplifier and subwoofer are functioning, follow these tuning recommendations for the best sound:
- If using a factory head unit, keep in mind that its output is voltage-regulated. This means that as you increase the volume, the head unit sends more power.
- If the amplifier gains are set too high with a low volume setting, your door speakers may peak before the subwoofer reaches its full potential.
Recommended Tuning Process:
- Turn the gain adjustments on both the amplifier and subwoofer all the way down (lowest setting).
- Play a song that will last for at least a few minutes.
- Increase the volume on the head unit to about 75% of max volume.
- Using a small flathead screwdriver, adjust the Front Gain setting on the amplifier until you reach your desired sound level.
- Repeat the process for the Rear Gain setting on the amplifier.
- Adjust the Sub Gain setting on the subwoofer.
- Fine-tune the Crossover setting on the subwoofer to your preferred level.
Final Adjustments & Sound Tweaks
- If you hear distortion, clipping, or the sound cuts out, the gain is set too high.
- Adjust the EQ settings within your head unit to fine-tune the sound.
- If using an aftermarket head unit, ensure that the subwoofer output is turned on in the head unit settings menu.
Contact Us
If you're still encountering difficulties and need additional troubleshooting support, please reach out using this contact form, and someone will get in touch as soon as possible.
