Alpine PWE-S8 Underseat Subwoofer Step By Step Install On the 5th Gen 4Runner
The stock 4Runner sound system may not have enough bass for your preferences.
An under-seat subwoofer is a great option to get more bass without taking up lots of space in the trunk. After a lot of research, I chose the Alpine PSE-S8 and I am pleased with the results.
It helps to fill in the missing bass nicely. It’s not a window shaking monster, but I listen to some bass-heavy music and am still happy with the improvement over the factory sound system.
If you are not looking for something incredibly bass-heavy but rather crystal clear sound with punches smaller punches of bass, check out the OEM audio plus system. It’s going to be a little more expensive but everyone that installs it seems to really like it.
Products & Parts Needed For Install:
- Alpine PWE-S8 Subwoofer: Check price
- 1000W Wiring Kit: Check price
- Wire Crimps: Check price
- USA made crimper: Check price
- T-Taps: Check price
- Wire Harness Tape: Check price
- Zip Tie Surface Mounts: Check price
- High Temp Tape: Check price
Alpine PWE-S8 Underseat Subwoofer Install
- Remove Seat
- Cover Vent
- Attach Subwoofers
- Run Powder Supply Wire Through Firewall
- Connect to Battery
- Organize 12V Line in Engine Bay
- Organize 12V Line Near Footwell
- Remove the Center Console
- Tap into Stock Speaker Wires
- Attach New Speaker Wires
- Tap Remote Wire
- Attach All Wires to the Sub Harness
- Clean up All of The Wires
- Attach Remote Control
- Connect the Ground & Final Adjustment
- End Results & Final Thoughts
OVERVIEW OF WIRES
A subwoofer can pull quite a lot of amps so you will want to use a thick wire for the power supply and ground.
The wiring kit will come with 4 wires that you will use.
Assuming you buy the same kit linked above, you will use the blue wire for the 12V supply. This will be connected directly the battery, passed through the firewall, and then connected to the subwoofer.
The black wire will be used to connect the subwoofer to the closest ground, in this case, one of the bolts for the seat.
The clear speaker wire will be used to connect the subwoofer to the stereo.
The grey wire will be the “remote” wire that you will connect to a 12V source that is only on when the rest of the accessories are on, in this case, a 12V outlet in the center counsel. This will tell the subwoofer when to be on.
The wiring kit will also come with a large fuse that you will connect inline to the power source line. The subwoofer will also come with a wire harness that you will solder or crimp all of the connections to. It will also come with remote control.
Step 1. Remove Seat
Start by disconnecting the ground on the battery and then wrapping the ground in a rubber glove or similar so it won’t accidentally make contact later.
If you leave the battery connected with the seat disconnected you could possibly cause a fault in the airbag system.
Remove the 4 bolts holding the seat to the floor and then disconnect the wires under the seat. I leaned my seat back and out of the way instead of removing the heavy seat entirely from the vehicle.
Also, remove the kick panel trim to the left of the seat.
Step 2. Cover Vent
The foot vent under the seat will blow directly on the subwoofer and possibly overheat it.
Step 3. ATTACH SUBWOOFER
Attach the supplied brackets to the subwoofer only on the side closest to the vent.
Place the subwoofer as shown in the photo, centered with the seat bolt holes and as close to the vent as possible. I used some ¼” screws I had on hand to screw the brackets into the carpet.
You can find some similar screws at your local hardware store.
You should only use the brackets that are closest to the vent because there is padding below the carpet here that will prevent the screws from rattling on the metal floor.
Step 4. Run Powder Supply Wire Through Firewall
Use an X-Acto or similar knife to cut a small hole through the large grommet on the firewall near the ABS module.
Push the thick blue wire through the hole. A small amount of soap will help with this.
Step 5. Connect to Battery
Step 6. Organize 12V Line in Engine Bay
Run the wire between the fuse box and battery and then along the driver’s side engine bay wall.
Step 7. Organize 12V Line Near Footwell
Remove the plastic trim on the left side of the footwell.
There are a few clips holding it in as well as a plastic bolt toward the back. Tuck the blue wire behind the existing wires so that it won’t be in the way of the trim.
Step 8. Remove the Center Console
There are a number of videos online that can show this much better than I can type it.
In summary, start by removing the two long pieces of trim on each side of the center console. They are just held in by clips so you can grip and pull on them to pop them off.
Next, remove the AC controls by removing a few bolts and then pulling on it.
Finally, remove the radio by removing the 2 bolts holding the bottom of it in and then pulling outward on it. Remove all of the connections on the back.
Step 9. Tap into Stock Speaker Wires
Use the t-taps to connect the speaker wires.
There are reports of people having problems when using the front speaker lines so use the rear speaker lines instead.
Find the connector with the wires matching what is in the photo.
Step 10. Attach New Speaker Wires
Run the new speaker wires from the head unit location down to the shifting area.
Step 11. Tap Remote Wire
Use another T-Tap to tap into the green and white 12V line that goes into the armrest storage.
Step 12. Attach All Wires to the Sub Harness
Run the new speaker wires from the front of the shifter area to the back.
Pull the wires down to the subwoofer by going under the trim as shown in the photo.
Also, pull through the remote control wire that came with the subwoofer. Attach a crimp to the existing ground wire.
Step 13. Clean up All of The Wires
Wrap all of the wirings in wire loom harness tape to give a cleaner appearance.
Step 14. Attach Remote Control
There are many possible options for where to mount the remote control.
I chose to mount the remote as shown in the photo above as it gives easy access near the natural resting position of my hand.
Step 15. Connect the Ground & Final Adjustment
Replace the seat. Then, connect the ground ring crimp to the nearby bolt.
End Results & Final Thoughts
In this photo, you can see how much the subwoofer sticks out with the seat in the far back position.
Test the subwoofer with some bass-heavy music. Adjust the subwoofer remote from the min to max position and listen for the difference. If the bass gets louder, it is set up correctly.
If it gets quieter, the phase is wrong. If the phase is wrong you can easily flip it by flipping the phase switch on the subwoofer.
Enjoy your added bass!