No Bass in JBL Rear Subwoofer & Rear Door Speakers

[FoozGrind]

I still think Toyota set this to soundt

You all are assuming you think you know how the JBL sound system in the Toyota is designed to work. It's not as you expect:

On Toyota/JBL systems (including current 4Runner, Tacoma, Tundra, Sequoia):
• The subwoofer is tied to the “front” audio stage, not the rear channels.
• When you move the fader fully to the rear, you aren’t just shifting the mids/highs — you’re effectively telling the system to focus audio output on the rear channels only.
• Because of that, the amplifier reduces or completely cuts subwoofer output when the fader is moved to the rear.

So:

Middle or forward fader = full system, including subwoofer

Rear fader = primarily just the rear door speakers, subwoofer mostly disappears

This is intentional by design. Toyota/JBL stage the system around the front seats, since that’s where the driver and most listeners are. Bass is part of that staging.

see that’s what I am thinking that it’s designed to be this way. Stupid question I am no audio engineer or anything but right now it sounds fine to me in the front and it sounds decenentish if I sit in the backseat. Ok so let’s assume Toyota fixes whatever and the bass is now louder in the rear and sub… so if I keep my bass just above half way how would that sound then to the rear passengers? I am thinking Toyota didn’t want to blast the rear people out of their seats I dunno I could be wrong I honestly have no idea. I do know the 25 Camry jbl does sound wayyyyy better but it’s also a car and the sub is right in the rear dash

Sponsored

 

[6thGen1419]

I still think Toyota set this to soundt


see that’s what I am thinking that it’s designed to be this way. Stupid question I am no audio engineer or anything but right now it sounds fine to me in the front and it sounds decenentish if I sit in the backseat. Ok so let’s assume Toyota fixes whatever and the bass is now louder in the rear and sub… so if I keep my bass just above half way how would that sound then to the rear passengers? I am thinking Toyota didn’t want to blast the rear people out of their seats I dunno I could be wrong I honestly have no idea. I do know the 25 Camry jbl does sound wayyyyy better but it’s also a car and the sub is right in the rear dash

You can confirm by setting the fader at middle or even more towards the front and verifying the subwoofer is correct by playing a subwoofer test track and sticking your head into the back cargo area.

 

[6thGen1419]

I still think Toyota set this to soundt


see that’s what I am thinking that it’s designed to be this way. Stupid question I am no audio engineer or anything but right now it sounds fine to me in the front and it sounds decenentish if I sit in the backseat. Ok so let’s assume Toyota fixes whatever and the bass is now louder in the rear and sub… so if I keep my bass just above half way how would that sound then to the rear passengers? I am thinking Toyota didn’t want to blast the rear people out of their seats I dunno I could be wrong I honestly have no idea. I do know the 25 Camry jbl does sound wayyyyy better but it’s also a car and the sub is right in the rear dash

There is nothing for Toyota to fix. The JBL sound system is working as designed.

 

[The_Dark_Knight_Forever]

You all are assuming you think you know how the JBL sound system in the Toyota is designed to work. It's not as you expect:

On Toyota/JBL systems (including current 4Runner, Tacoma, Tundra, Sequoia):
• The subwoofer is tied to the “front” audio stage, not the rear channels.
• When you move the fader fully to the rear, you aren’t just shifting the mids/highs — you’re effectively telling the system to focus audio output on the rear channels only.
• Because of that, the amplifier reduces or completely cuts subwoofer output when the fader is moved to the rear.

So:

Middle or forward fader = full system, including subwoofer

Rear fader = primarily just the rear door speakers, subwoofer mostly disappears

This is intentional by design. Toyota/JBL stage the system around the front seats, since that’s where the driver and most listeners are. Bass is part of that staging.

This is interesting.
I'm not saying you're wrong but could you kindly share a link or something from an expert source that provides more insight into this system design choice?

 

[Tarekith]

It's easy to test, just leave the front-rear fader in the middle or all the way to the front and listen to the sub. If I put mine all the way to rear, you're right nothing really comes out of the sub. If you put it in normal listening position and listen with the volume above 20-25 it's pretty easy to hear the sub working from the back hatch area.

It's still a small and likely underpowered stock subwoofer, so it's not going to shake your windows lose or anything like that. But it definitely does what a sub is supposed to do and reinforces the low end below about 70-80Hz.

 

[6thGen1419]

AI (ChatGPT):

Question:
2025 TOyota 4Runner Off Road Premium comes with Premium sound, JBL speakers throughout with speakers in the rear door and a subwoofer in the cargo area. Sound system has a balance and fader controls. Is this a normal part of the design of the JBL sound system: "Everything sounds fine when fader is set to middle or forward, but sounds like there’s no bass when fader set to rear. Listening from the rear hatch, I can hear the subwoofer playing and it sounds good when fader is set to middle, so it seems like the subwoofer is at least functional."

Answer:
Your description is very consistent with how many factory systems—especially JBL/Toyota—are set up, so what you’re observing is likely normal behavior and not a defect.

What’s happening?

On Toyota/JBL systems (including current 4Runner, Tacoma, Tundra, Sequoia):

• The subwoofer is tied to the “front” audio stage, not the rear channels.
• When you move the fader fully to the rear, you aren’t just shifting the mids/highs — you’re effectively telling the system to focus audio output on the rear channels only.
• Because of that, the amplifier reduces or completely cuts subwoofer output when the fader is moved to the rear.

So:

Middle or forward fader = full system, including subwoofer

Rear fader = primarily just the rear door speakers, subwoofer mostly disappears

This is intentional by design. Toyota/JBL stage the system around the front seats, since that’s where the driver and most listeners are. Bass is part of that staging.

Why design it this way?
Factory systems prioritize:

• Front-soundstage clarity
• Imaging (vocals and instruments based toward the front)
• Reduced interference from rear reflections

Subwoofer output is usually mixed into the front channels, not equally distributed to both front and rear. When you fade to the rear, the system thinks, “Okay, play only the rear speakers,” so the sub doesn’t get the same signal.

Your observation matches that:
Subwoofer plays when fader is centered

Subwoofer sounds good when listening from the rear hatch

Bass disappears when fader is pushed all the way rearward

This all points to a correctly working system.

You cannot change this behavior through settings on the stock head unit.

However, some people add:

• A DSP (signal processor)
• Aftermarket amp
• Or a subwoofer integration harness (PAC/Metra)

…to get independent control.

Bottom line

Yes — what you’re describing is normal for Toyota’s JBL system. The subwoofer is tied to the front audio stage, so fading to the rear will make the bass seem to disappear. Nothing is broken.

If you want, I can also show you where in the wiring diagram the sub is tied to the front channels in the JBL amp for the 4Runner.

 

[Vahn]

After reading all 12 pages of this thread, I was really curious. I've never even been in the passenger or back-seat, so it never occurred to me even think about how it sounds from different listening positions.

My experience is like many others.

If I put the bass at the highest setting possible, and then push the balance to rear speakers only:

The bass is indeed incredibly anemic, almost none compared to the front speakers, while sitting in the rear seats.

In the cargo area, you can feel the lowest lows and hear them. Far more than the rear passenger seats but nowhere close to a center or front-bias speaker balance.

I am not here to express an opinion about whether the lack of bass in the rear seating position is good enough for the "premium" (as the OP puts it) sound system.

I am just reporting results.

My completely unsolicited and amateur opinion is that the system is working as designed. I could do without the gimmicky center removable speaker, and this system is certainly not as premium as others I've had, but it's not horrible by any means.

 

[6thGen1419]

After reading all 12 pages of this thread, I was really curious. I've never even been in the passenger or back-seat, so it never occurred to me even think about how it sounds from different listening positions.

My experience is like many others.

If I put the bass at the highest setting possible, and then push the balance to rear speakers only:

The bass is indeed incredibly anemic, almost none compared to the front speakers, while sitting in the rear seats.

In the cargo area, you can feel the lowest lows and hear them. Far more than the rear passenger seats but nowhere close to a center or front-bias speaker balance.

I am not here to express an opinion about whether the lack of bass in the rear seating position is good enough for the "premium" (as the OP puts it) sound system.

I am just reporting results.

My completely unsolicited and amateur opinion is that the system is working as designed. I could do without the gimmicky center removable speaker, and this system is certainly not as premium as others I've had, but it's not horrible by any means.

When you're turning down the front speakers by adjusting the fader all the way to the rear speakers, you're also turning down the subwoofer because the subwoofer is tied to the front speakers. It's as designed.

 

[Vahn]

When you're turning down the front speakers by adjusting the fader all the way to the rear speakers, you're also turning down the subwoofer because the subwoofer is tied to the front speakers. It's as designed.

I understand this completely. I even stated that I think it's as designed, as many others posted and believed. My results are really for the OP, who might actually have a problem or it just doesn't work good enough for him.

 

[Bernie]

Okay, after testing multiple settings (keep in mind that I was reasonably satisfied to start with) I’ve found that setting bass to max and highs and mid-range to halfway up, then setting fader to the middle of the back seats, produces the best sound. I can hear the subwoofer just fine. Sure, the JBL isn’t aftermarket audiophile maxed out quality, but it’s a pretty good system for being factory equipment.

 

[6thGen1419]

My preference is to set all the balance/fader controls to center/middle and all treble, bass controls to zero. Sounds the best to me and allows for the closest to the way the music was mixed and recorded. I get plenty of bass, highs and mids. Jazz and Bluegrass sound great.

 

[Tarekith]

Same. My day job is an audio mastering engineer and I used to compete in IASCA back in the day and the default settings sound the most accurate to me. Maybe occasionally I’ll bump the bass up one notch for party mode.

But also, the whole reason they give us these controls is so people can make it sound the way we want. One thing I’ve learned in 30+ years of audio engineering is that everyone hears things differently.

 

[6thGen1419]

Same. My day job is an audio mastering engineer and I used to compete in IASCA back in the day and the default settings sound the most accurate to me. Maybe occasionally I’ll bump the bass up one notch for party mode.

But also, the whole reason they give us these controls is so people can make it sound the way we want. One thing I’ve learned in 30+ years of audio engineering is that everyone hears things differently.

We're on the same page. Way back in the day (1980s) I was an audio electronics engineer making active circuit (pre-digital days) sound processors for recording studios and AM/FM broadcast stations.

 

[WayneAllan]

I thought it was just a not so great stock sound system, despite being JBL and having a "sub" in the rear, same experience here, all low end comes from the front door speakers, rear doors and sub are pretty useless, very quiet, is it not supposed to be this way? lol following for sure, the fact that there is no separate volume or settings for the sub says a lot

 

[dgorman]

Can’t wait for a new harness and an arc audio amp solution

Sponsored