Sponsored

No Bass in JBL Rear Subwoofer & Rear Door Speakers

OP
OP
The_Dark_Knight_Forever

The_Dark_Knight_Forever

TRD Sport Premium
Well-known member
First Name
J.
Joined
Mar 31, 2025
Threads
6
Messages
213
Reaction score
83
Location
Houston, TX
Vehicle(s)
2003 Toyota Tundra SR5 TRD Sport Stepside
I'm having a hard time believing this is a hardware issue. I think it probably is a software issue. Perhaps a glitch developed that caused the change in the bass of the rear speakers. Just speculation at this point but again at least I'm not the only one in the boat which leads me to believe that it's a software issue.
Sponsored

 
Last edited:

jrenzag

TRD Pro
Well-known member
Joined
Jan 29, 2025
Threads
9
Messages
67
Reaction score
50
Location
Raleigh NC
Vehicle(s)
2012 Jeep Grand Cherokee Overland
OP
OP
The_Dark_Knight_Forever

The_Dark_Knight_Forever

TRD Sport Premium
Well-known member
First Name
J.
Joined
Mar 31, 2025
Threads
6
Messages
213
Reaction score
83
Location
Houston, TX
Vehicle(s)
2003 Toyota Tundra SR5 TRD Sport Stepside
Probably not related but, the new Lexus GX 550 is experiencing a rear audio fade widespread issue. There is a huge online thread discussing the potential cause, which appears to be related to the amplifier and/or the rear fade software.

Thread 'Mark Levinson 21-speaker audio sounds terrible on the GX 550 Luxury +' https://www.lexusgxforum.com/thread...dio-sounds-terrible-on-the-gx-550-luxury.463/
Thank you for posting this information & lead to follow! Much appreciated. 🙏🏻
 

jrenzag

TRD Pro
Well-known member
Joined
Jan 29, 2025
Threads
9
Messages
67
Reaction score
50
Location
Raleigh NC
Vehicle(s)
2012 Jeep Grand Cherokee Overland
I had an aftermarket subwoofer (and dedicated amp) installed on my ORP. It taps into the software signal from the OEM sub. Fwiw, when I fade all the way to the rear my aftermarket subwoofer signal is still the same and sounds no different. So this doesn't make me think it's a software issue with the OEM JBL sub.

Having said that, imo... all of the OEM JBL speakers in the 6g sound like crap especially the rear passenger doors. And the rear cargo speakers are absolutely doodoo garbage. I installed the beat sonic amp behind the 14" infotainment system and it helped some but overall just really disappointed in the entire system.
 
OP
OP
The_Dark_Knight_Forever

The_Dark_Knight_Forever

TRD Sport Premium
Well-known member
First Name
J.
Joined
Mar 31, 2025
Threads
6
Messages
213
Reaction score
83
Location
Houston, TX
Vehicle(s)
2003 Toyota Tundra SR5 TRD Sport Stepside
I had an aftermarket subwoofer (and dedicated amp) installed on my ORP. It taps into the software signal from the OEM sub. Fwiw, when I fade all the way to the rear my aftermarket subwoofer signal is still the same and sounds no different. So this doesn't make me think it's a software issue with the OEM JBL sub.

Having said that, imo... all of the OEM JBL speakers in the 6g sound like crap especially the rear passenger doors. And the rear cargo speakers are absolutely doodoo garbage. I installed the beat sonic amp behind the 14" infotainment system and it helped some but overall just really disappointed in the entire system.
Thanks for sharing. That's interesting to know. Does a break in period of 30 hours or so help to improve the OEM JBL speakers?
So perhaps Brian Day is on to the solution by getting the amplifier under the driver's seat replaced by his delaership?
Brian, inquiring minds want to know buddy! Please post when you've got your new amp installed.
 
OP
OP
The_Dark_Knight_Forever

The_Dark_Knight_Forever

TRD Sport Premium
Well-known member
First Name
J.
Joined
Mar 31, 2025
Threads
6
Messages
213
Reaction score
83
Location
Houston, TX
Vehicle(s)
2003 Toyota Tundra SR5 TRD Sport Stepside
I had an aftermarket subwoofer (and dedicated amp) installed on my ORP. It taps into the software signal from the OEM sub. Fwiw, when I fade all the way to the rear my aftermarket subwoofer signal is still the same and sounds no different. So this doesn't make me think it's a software issue with the OEM JBL sub.

Having said that, imo... all of the OEM JBL speakers in the 6g sound like crap especially the rear passenger doors. And the rear cargo speakers are absolutely doodoo garbage. I installed the beat sonic amp behind the 14" infotainment system and it helped some but overall just really disappointed in the entire system.
Seems unusual that others in this thread having the same problem could all have faulty amps. I guess it's possible though. I'm still thinking & hoping it's more of a software issue requiring an update because the mids & high work fine on the rear door speakers but only the bass is practically non-existent. As soon as I can get to a dealership to check out a new 4Runner on the lot I'll do so & report back but in the meantime I'm appreciating all who are sharing in this thread & helping solve the problem. 🙏🏻
 
Last edited:

sftonyc

Limited
New member
Joined
Nov 6, 2025
Threads
0
Messages
3
Reaction score
3
Location
CO
Vehicle(s)
2025 4Runner Limited
I looked through the Lexus GX thread, and it looks like this issue actually started on the Lexus TX. Enough owners complained to Lexus directly that they issued a TSB for the Lexus TX that sounds pretty much identical to the bass 4Runner problem. It calls for replacing amps that are below a certain software revision. The TSB file is attached below.

The GX owners started a FB group to try to get it expanded to them as well, since they're having the same issue. Sounds like the 4Runner may have the same issue too. I haven't had a chance to check mine yet, but it would be interesting to see if the software versions listed for the 4Runner amps are the same too as specified in the TSB (AP SW Version <1400).

Lexus brands their premium sound system Mark Levinson and Toyota brands it JBL, but both brands are part of Harman (which is in turn part of Samsung), and I suspect use similar or the same underlying hardware.
 

Attachments

ToYoDaMan

TRD Off-Road Premium
Well-known member
First Name
Allan
Joined
Sep 11, 2025
Threads
1
Messages
157
Reaction score
71
Location
Bay Area
Vehicle(s)
Toyota
Y'all got me worried. Didn't realize this could even be a problem. Going to have to test mine out this weekend. Hoping it's all good on mine. We will see.
 
OP
OP
The_Dark_Knight_Forever

The_Dark_Knight_Forever

TRD Sport Premium
Well-known member
First Name
J.
Joined
Mar 31, 2025
Threads
6
Messages
213
Reaction score
83
Location
Houston, TX
Vehicle(s)
2003 Toyota Tundra SR5 TRD Sport Stepside
I looked through the Lexus GX thread, and it looks like this issue actually started on the Lexus TX. Enough owners complained to Lexus directly that they issued a TSB for the Lexus TX that sounds pretty much identical to the bass 4Runner problem. It calls for replacing amps that are below a certain software revision. The TSB file is attached below.

The GX owners started a FB group to try to get it expanded to them as well, since they're having the same issue. Sounds like the 4Runner may have the same issue too. I haven't had a chance to check mine yet, but it would be interesting to see if the software versions listed for the 4Runner amps are the same too as specified in the TSB (AP SW Version <1400).

Lexus brands their premium sound system Mark Levinson and Toyota brands it JBL, but both brands are part of Harman (which is in turn part of Samsung), and I suspect use similar or the same underlying hardware.
Thank you for this sharing this knowledge. 🙏🏻 Much appreciated. Sounds like a good lead to follow up on.
 
OP
OP
The_Dark_Knight_Forever

The_Dark_Knight_Forever

TRD Sport Premium
Well-known member
First Name
J.
Joined
Mar 31, 2025
Threads
6
Messages
213
Reaction score
83
Location
Houston, TX
Vehicle(s)
2003 Toyota Tundra SR5 TRD Sport Stepside
Y'all got me worried. Didn't realize this could even be a problem. Going to have to test mine out this weekend. Hoping it's all good on mine. We will see.
I hope so too, man. These vehicles are entirely too expensive to be messed up like this.
 
OP
OP
The_Dark_Knight_Forever

The_Dark_Knight_Forever

TRD Sport Premium
Well-known member
First Name
J.
Joined
Mar 31, 2025
Threads
6
Messages
213
Reaction score
83
Location
Houston, TX
Vehicle(s)
2003 Toyota Tundra SR5 TRD Sport Stepside
This is the amp under the driver‘s seat. For some reason Toyota decided to cover it up with carpet. I cut open the carpet
IMG_8091.webp
Thanks for showing us. I can't imagine why Toyota would think it's a good idea to cover an amplifier with carpet. My amp in my Tundra gets pretty warm without carpet covering it & hot when I'm pushing it.
 

6thGen1419

TRD Off-Road Premium
Well-known member
First Name
Peter
Joined
Sep 18, 2025
Threads
12
Messages
157
Reaction score
88
Location
New Mexico
Vehicle(s)
2025 4Runner TRD Off Road Premium iForce Max
So the bass in the rear doors & subwoofer in yours is the same as it is in your front speakers?
went and tested the subs in my platinum here is the sound clips.

1st clip : 2025 4R Platinum rear bias full bass
2nd clip : 2025 4R Platinum center bias full bass
3rd clip : 2023 Tundra Platinum rear bias full bass
4th clip : 2023 Tundra Platinum center bias full bass

you can definitely tell the difference in bass punch in the rear on the tundra vs the 4R and center is even more dramatic







invalid comparison because completely different audio source between 4Runner and Tundra.
Sponsored

 
 







Top