7th Gen Lexus ES300h & ES350 2019+ Subwoofer Install
Adding a subwoofer to the stock 2019+ Lexus ES300h and ES350 standard 10-speaker or 17-speaker ML is easy. This DIY/guide is based on my particular install on my 2021 ES300h with standard 10-speaker audio system. To my understanding, based on reading the wiring diagrams, the wiring/amp pinout is the exact same as the 17-speaker premium ML system. Do your own research to confirm first before performing any work. If you do not feel confident in working on your car, take your car to an audio shop! If you have a hybrid, take extra care around the large battery pack beneath the seat. This can cause serious harm or even death if you get shocked by it. Just be extra careful.
What I used or is needed:
10mm socket (for battery terminal)
13mm socket (for seatback ground bolt for amp ground)
Tesa Insulation tape (for a professional OEM install to wrap the wires)
Advanced/experienced installers can skip to the wiring/pinout information. The installation of a subwoofer is pretty basic and the same across all cars except for the exact wires you'll need to tap for audio signal.
Run your power and ground. The amp kit will come with ring terminals. This is where a heavy duty solid wire crimper is needed. For power, start by opening the trunk. The 12V battery is in the trunk on the passenger side. You lift the carpeted flap up to reveal the battery. Using your 10mm socket, attach your power line. Remove the fuse for now so you don't touch the power wire to ground causing a spark or a short. Install the fuse at the very very end to be safe! You won't need much 12V power cabling because the battery is in the trunk where you'll keep your sub. So make sure you cut after so you know how much cable you need.
Next you'll need to run your ground cable. The length should be no more than 30" according to the manual of my Rockford Fosgate subwoofer. So I cut it to 30". For this step, I removed the rear bottom seat cushion. Simply pull up on each side and the seat cushion pops upward and out. (Upon reinstall, make sure the seatbelt buckles slot into the holes of the cushion.) I used one of the metal bolts holding the seatback to the chassis to ground my amp. Use a 13mm socket. You'll need to carefully fish the wire through slots/holes at the bottom/back of the seat into the trunk. Use a flashlight. A hanger wire taped to your wires may aid you fishing the wire. There's plenty of slots/holes to feed wire through. Make sure you don't have wires touching any sharp metal. Zip tie them down if needed. Reinstall the seat last. You'll need to run some extra wires across the driver's side to the amp under the driver's seat and subwoofer control under the drivers footwell.
You'll need to access the stock amp. For both the standard and ML audio systems, the amp is under the driver's seat. You do NOT need to remove the seat to access the amp. Simply move your seat forward and as high as it will go. You'll need to remove the headrest first by tilting the seat back.
The amp has a plastic cover held on by three plastic rivets. Use a flat-blade screwdriver to remove.
The harness you'll need is the farthest right one, towards the front of the car. Naturally these wires are the wires that carry the amplified power so they are heavier duty for function and longevity.
These are the wires on both the standard and ML amp. Same harness, same colors according to my research. If your amp/harness does not look like this, you may need to do some research. Also this is for my 2021 ES300h standard audio system. Your year/model may vary.
Wires #6 and #21 blue and tan are the stock subwoofer output wires. Tap your high-level input harness to these. Since the Rockford Fosgate high-level input harness has two pairs of power and ground for two speakers, just splice both positives and both negatives of the Rockford Fosgate harness together, then you'll have one positive and one ground to tap into the stock harness blue/tan. The polarity doesn't matter here as the amplifier will usually have a phase switcher.
While you're here, also tap the remote wire. (DO not rely on the high-level input to power on the sub--i made this mistake and got a very loud rumble for three seconds every time i shut off the car.) You'll need to use a remote turn on lead to ACC/switched 12V. I used a multimeter and the wiring diagram to find a switched 12V wire to tap on the left-most (first) harness on the amp. I used the white wire on the upper top corner. Use a multimeter to confirm it's 12V when ignition ON and 0V when off. Run this wire along with your signal wire across the left side of the car (just use your fingers to stuff them in the plastic sill covers (or remove them if you want) and run them to the trunk.
Run your signal wire as well as the remote wire and volume bass knob wire here. A total of three wire groups. I tucked them more neatly after I took this photo. This is just to show the general area where I ran the wires. A bright light can help you see holes to fish the wires through.
Wires wrapped in Tesa tape (see link above) for a professional clean tidy look. Notice in the second pic, I wrapped the bass control knob wire together with the other wires. This particular subwoofer/amp combination is nice because you can easily detach the wires when you want to remove the sub. It has a quick disconnect.
This subwoofer also comes in 10" and 12" models. The boxes for both are bigger.
Overall this setup provides a nice kick to the stock setup, particularly with my upgraded dash speakers. Nothing crazy, just a bit of added low end to complete the sound stage.
Using my Amazon Affiliate links, I get a small percentage of each purchase. It does not affect you. I appreciate it! Also shout out to Crutchfield who helped me made this happen. They sell the sub at this link: https://www.crutchfield.com/S-B37Ou8pVaDi/p_575P3008P/Rockford-Fosgate-P300-8P.html