2004 DC JBL amp bypass

Just upgraded my two front speakers to Rockford fosgate. Prior to that I only had sound from the front right old speaker. I figured it was something wrong with the wiring and that was why I only had sound from the front rear speaker. After getting them installed, the audio guy informed me that the reason your sound isn’t equal on both sides is because your Amp is starting to go bad. He suggested upgrading and quoted ($500-700) or he could bypass for $150 ish, but stated the sound wouldn’t be near as good. So first, I don’t need “great” sound, I just want equal sound on the front two door speakers so I can listen to podcasts etc. my days of a kickass sound system and subs are long gone. My question is there an easy way or DYI instructions on how to bypass the amp yourself? Could I just wire the two new speakers directly into the head unit (have a double din Kenwood). There’s no way I’m spending $500-700 just to upgrade the amp and I’d rather try and figure out the bypass myself before forking out another couple hundred. Currently only have sound on the front rear Rockford fosgate, and the driver front is just making an low annoying buzzing sound. And help is appreciated. Haven’t been able to find much so far with my exact scenario.

 

Metra 70-8117 Amp Bypass Harness

$35 Metra 70-8117 Factory Amplifier Bypass Harness fits Select 2003-2006 Toyota Vehicles

https://www.amazon.com/Metra-70-8117-Factory-Amplifier-Vehicles/dp/B000A3THKQ

yes

 

In my 4 runner, had to do JBL bypass by running the metra harness from right rear quarter to new head unit. Wasn’t super fun but sound was immediately improved.

 

What do you mean running from the right rear quarter? Like the amp is in the rear?

 

If you use the bypass wiring harness it plugs into the factory wiring at amp located behind the drivers side rear passenger seat back in the DC Tundra. You then have to run the wires from back there to the head unit. I ran mine in the channel under the drivers side cab/door trim to head unit.

 

Nice, I’ve pulled both of those two trim prices up before and have seen there is quite a bit of room to run wires. I think I’ll get that harness and give it a try. Hopefully that will balance out the sound

 

Not to hijack this thread, but I'm in a similar situation and was wondering if you wanted to keep the JBL amp and speakers, but replace the just the JBL head unit, is that possible?

I've been under the assumption that if you want a new head unit, you're basically looking at bypassing the amp and replacing all the speakers as well.

 

And if you have an aftermarket HU do you bypass amp w factory jbl speakers ?

 

In 4th gen 4Runner I was referencing, the jbl amp is in the cargo area above the right rear wheel.

 

You can keep the speakers, but for $90 from crutchfield you can get four nice 3-way Rockford Fosgate 6.5” replacements including wiring adapters and trim rings.

 

Are these the ones u used w new HU and factory amp?
https://www.crutchfield.com/p_575R1675S/Rockford-Fosgate-R1675-S.html?tp=105

 

I took out the factory amp in my 4Runner which had jbl. I used these in my 4Runner and both front and rear doors of my 07 Tundra. Not sure why crutchfield doesn’t think they fit the rear on the tundra.

https://www.crutchfield.com/p_575R165X3/Rockford-Fosgate-R165X3.html?tp=105

 

All speakers in your truck are wired to that amp. To continue using the factory amp, you'd need to find a way to deliver the same (low or high) level input from the new stereo to the amp, which sadly requires some splicing to do correctly and safely. I guess the big question is, why would you want to keep the JBL amp?

With the advancements in car audio these past 15-20 years, they're packing just as much tech into modern mid-grade head units as that amp. If you must stay OEM, get a pinout for the JBL amp, splice accordingly, but I recall some squirrely quirks to the input/output lines to/from the factory amp, you've probably got work cut out for you.

Meanwhile, you could buy the advertised harness above to extend the speaker lines from the JBL amp up to your new head unit, then use your head unit's integrated amp. Much easier. If you've got a hard-on about using a standalone amp, look at this Alpine unit, which has a 4x100w amp that piggy-backs onto it, all cleanly behind your dash.

https://www.alpine-usa.com/product/ilxw650_kta450_power-duo_package

You'd still need to use the amp bypass harness, though, unless you plan to rewire every speaker (overkill).

There are at least two people who've repurposed the amp. But in the process, they lost the ability to either fade F/R or balance L/R, I forget which, and I forget why.

Quick edit - note: That 450w amp is still a typical amplifier. You'll need a proper amp wiring kit, from the battery, to power it. The factory amp is fed with a tiny, undersized wire. It's not exactly very sophisticated.

PS - I assume you know 100% you have the JBL system. There was a JBL and non-JBL system in our trucks that had an amp. If the head unit doesn't say "JBL" somewhere, chances are it's what I had: A non-JBL 6-disc 6-speaker truck.

 

Speaking of a 2004 DC only, my rears are ~5-1/4, which is why Crutchfield says those won't fit in mine . The Hertz X 170(Fnt) and Hertz X 130(Rear) hooked to my Kenwood Excelon DDX8906S makes this ole farts heart beat fast when crusin on Stairway to Heaven. Screw the JBL Amp !


.

 

Hey, thanks for the reply! I could care less if I'm using the amp or not. The main concern I had was that I've heard that the JBL speakers are rated at some weird ohm level, and that it could overheat an aftermarket head unit if you were using the jbl speakers. What I heard could be completely wrong. The main reason I ask is purely for the sake of cost. I'm fine with the sound of the speakers in my truck, and if I can replace the head unit with a touch screen, and not need to replace my speakers, I'm much more likely to do it.

 

JBL used 2 ohm speakers.

Standard and many aftermarket are 4 ohm.

 

When I helped one of the other forum members in north ATL retrofit his pickup pre-pandemic, rear doors were 4ohm (Toyota p/n 86160-0c060). Front doors had the woofer and tweeter, both 2ohm, wired in series IIRC, thus presenting a 4ohm at the amp. Kicker has a great doc on how to change your impedance load based on wiring. It's worth a read if you're really interested in how this works, rather than relying on he said/she said. It's pretty basic.

Lower impedance will cause your amp to drive harder ... like, a 4ohm load to a 100w amp may push 100w, but when you drop that load, depending on the amp, it may try to push 150w due to its internal circuitry. You can create higher or lower loads (see doc above) using parallel/series wiring correctly to change the apparent load of your speakers. There's a reason speakers - especially subwoofers - come with different impedances, from 1/2 ohm to 8 ohm. If you want to run your subwoofer amp mono (non-stereo) at a 1ohm load to really milk every last ounce out of it, there are multiple ways to achieve that depending on what impedance subs you choose, and you can even go with single voice coil (SVC) or dual voice coil (DVC) subs with specific impedances to adjust that.

Ever since I worked as an installer at a shop that primarily sold JBL amps and drivers back in the mid-90s, I've used JBL's speakers for all my mids/highs on nearly every install. There's a reason many concert venues use their speakers, they offer amazing sound repro at a friendly cost - what Infinity, Rockford, MB Quart and others are charging for their components is terrible bang vs. buck. I love JBL's "Club" series speakers for vehicles, and it's what I have in my '06. They intentionally make many of their components with 3ohm impedance to drive your amp a little harder. It's NOT going to fry your head unit unless you buy some crappy $100 no-name head unit from Kraco or Pyle at the local auto parts store or eBay.

Ultimately, you can choose anything you want. The important thing is this:

First, always properly wire things. Run dedicated power for any aftermarket amp, properly fused within 12"-18" of the battery, safely passing power wire thru the firewall with a grommet, using a proper ground near the amp installation point. Always use thick, sturdy ground for your head unit to a solid bare-metal part of your chassis to avoid alternator whine (I won't get into ground loops). DO NOT use electrical tape or wire nuts to tie your wires together, ideally crimp using a butt splice, or solder with heat shrink if you're one of those folks (solder can be overkill and detrimental in certain environments).

Second, if you intend to skimp anywhere, don't skimp on your head unit or amplifier. Don't buy "off" or "generic" brands with your head unit or amp, those things are driving your speakers, and if it shorts, it could blow everything. Your head unit is probably the single most important thing you can splurge on! I need to mention, there's a lot of fluff out there in the car audio world. Lots of BS products. Don't let it discourage you, don't get overwhelmed. Ask around, but know everyone has an opinion or bad experience with XYZ brand, anyone who's ever installed professionally or competed has their "never failed me before" brand they'll tout. Doesn't mean they're right, brand loyalty is strong and - yes - I'm no different with my love of JBL, but they have the results and support to back their product's value.

Third, if you don't know, don't be ashamed to ask questions. I don't work in the industry anymore, I moved into the technology world almost 2 decades ago, but have kept links with the car audio world since. I have nothing to gain trying to persuade you to buy something, and I know all the fundamentals, many install tricks which are still used today. I have a genuine love for music and audio, and I'm happy to help if I can

 

Thanks for the excellent write up! I've also been a long time fan of JBL, and I've been quite surprised at how good these 17 year old speakers still sound, even compared to newer vehicles I've owned. That's the reason I'm not opposed to keeping the JBL speakers, and just changing the head unit to a nice aftermarket one. But doing this, from what it sounds like, I just need to bypass the amp with the aforementioned harness, and let the aftermarket head unit power the original speakers. And that will keep steering controls functioning? (not a big deal if it doesnt)

Thanks again

 

My steering wheel functions don’t work anymore with the aftermarket head unit, but yes I bought the bypass harness kit and they are now powered by the amp within the head unit. My two front speakers are Rockford fosgate and they aren’t as loud as the rears though, especially front drivers side.

 

If you swap out the head unit in most cars with steering wheel controls, you'll need a steering wheel control adapter to "translate" the commands sent to the head unit when you press a button on the steering wheel. I personally used the Axcess

$68 ASWC-1 Steering Wheel Control Interface

ASWC-1 control adapter. Setup was about as simple as it gets, and it's able to auto-detect what settings are appropriate for your steering wheel controls and your stereo.

The stock JBL speakers are fine as long as the foams are intact. Speaker tech hasn't changed a ton, still a voice coil with cone with foam. Amplifier circuitry has changed considerably, with things becoming smaller and more powerful for digital amplifier circuits.

But yes, bare minimum, to keep stock speakers, steering wheel controls, and replace the head unit, you'll need the new head unit, a unit like the ASWC-1 to ensure steering wheel controls work, and the amp bypass harness to extend the speaker wiring from your amp back up to the new head unit. If you go to Crutchfield, they make ordering all this a snap. Once you pick a head unit, hop on the phone with one of their sales people - they make it so damn easy to make sure you get everything you need AND offer free phone support for install after. And their prices are on-par, sometimes better than other places - no worries of counterfeit/grey market electronics like you have with Amezon.

 

Circling back to this thread... I have the original JBL system in my 06 double cab and I've repaired the door speakers. The system sounds fantastic! I kind of want to replace the head unit with a modern touch screen with android auto ...

Can I simply swap out the head unit without bypassing the stock amp? I want to retain the factory amp and speakers. Is this possible?

 

Yes, but you need a kit (Axxess sells one) to retain the amp. However, you lose balance/fader controls when you do it, so if you're interested in having exact same audio, or having channel separation, it's not for you. We've also had a couple of people with that system come on here complaining about noise/sound quality problems, so I haven't and won't recommend it.

 

So with this hiring harness.


I have to run it from the amp, to the new deck.
Right?

 

This thread is for you, specifically the "Audio, audio upgrades and cameras..." section.

Before you get started, read that. Seriously. Don't rely on others to tell you what you need. Those bullet points give you everything you need to know (or link to everything you need to know), since there are at least a few different audio systems in these trucks, and how they work/what they require is totally different. Even for trucks with the same cabs, there are different options/needs/harnesses.