I was under the impression that it would not work with a 2019+ Mazda 3. Let us know otherwise!

 

Will do. For now I just want to find the TAU...

 

Are you able to follow the wiring harness from the amplifier? It lives under the front passenger seat so you could take the seat out to double check the hardness and such.

 

Might be making some progress. There's now a Remote Tuner near the antenna on the gen4s, so I think they ditched the separate TAU. Also, a separate TAU wasn't mentioned anywhere in the gen4 Workshop Manuals. So the MAZ2 is definitely going back.

Just ordered the PAC APH-GM02 AmpPro ($35) from Crutchfield based on a user's comment that it worked with the Bose system. This is one of the adapters I'm hoping will fit:

This is the rightmost plug on the back of the Bose amp:

Fingers (not signals) crossed...

 

You can't easily remove the entire glovebox on the 2019+ Mazda3s as far as I can tell (just the glovebox door and ceiling plate to change the cabin filter), but I don't think that's necessary now that Bose put the front main speaker in the cowl where the TUA used to be?

Off topic, but the glovebox is removable. The service manual shared on this website shows a different style glovebox (Canada, Europe??) that has the entire box swing out. US models have a lid that swings out and the box portion is stationary. To remove the glovebox, I had to remove the padded leather dash trim to reveal the last two screws. I also took off kick panels on both sides and an end panel on the dash that the door closes against. Removing the glovebox gives more access to the speaker down there, but I don't recall seeing any other audio components back there.

 

Do you remember where this goes by any chance?

I suspect the front trim piece but I'm hesitant to remove it again for just one clip.

 

Thank you. Yea, that's more or less what I meant by "easily." I was able to get it out after the 2 screws, but you definitely want to remove those before tugging on the compartment (luckily I didn't break anything). Hopefully putting it all back together today will be straight forward. Tapping those blue wires that go to the cowl main speakers is my plan B (or C?). I'm a bit surprised there are not more options for a model car that's been out for a couple of years already, but it's been fun and informative so I can't complain.

I think maybe that first pic is sort of what's left of the old TAU. More of a hub now instead? What I can't figure out is why the plugs on the amp all look different than the ones in the passenger kick panel.

Can you imagine the conversation with the electrical engineering department? "So yea, about that TAU. We're going to slap in some 2-liter main front speakers in that location instead, move the tuner closer to the antenna for a better signal, and convert the old TAU to a hub. Oh, and move that to the passenger kick panel too, mmmk?" Fever dreams ensue lol.

Here's an upside down picture of the back of the green middle plug on the amp:

Different plug, but I was thinking those colors might all be a good match to the black plug up top in my first picture:

If so, then that might be a second place to tap, but would require a 14 pin adapter from somewhere, which I haven't seen anywhere yet.

Updates to come...

 

Quick update: having looked over the 3 adapters that are included in the AmpPro package, in fact this is the one I'm hoping will work with the far LEFT plug of the Bose amp:

From the sounds of it, that's the easiest route if you're adding only a sub and letting the Bose power the existing remaining speakers (the other adapters will let you add your own speakers or swap out the amp I think). Hopefully that will tap the sub signal BEFORE the amp.

What I plan on doing this weekend, after the rain passes and I can remove the seat (note: disconnect battery to avoid curtain airbag issues. Kill 2 birds and run power cable thru firewall near where clutch pedal would be after you remove battery):

1) Butt splice with heat shrink connectors the 2 whites to the matching 2 whites, then the 2 grays to the matching 2 grays. I THINK what that will do is passthru (have no effect) on the audio to the main (cowl) speakers.

2) Connect the LONG end of the remaining blue wires marked "subwoofer" (those coming out of the female connector) to your amp/sub using your LOC.

3) Seal off the short ends of the blue wires. I'm hoping keeping these as dead-ends leaves the Bose subwoofer in the deck unpowered, but I was going to remove that anyways to increase airflow for the sub in the sedan trunk.

(ETA: Other than turning out to be the correct of the 3 adapters to use, and matching the wires by color, everything else in this post is 100% wrong).

 

The sealed, 12-inch Rockford Fosgate looks like it'll be a nice fit in the sedan trunk.

 

Success! Powered sub added to Bose system on Turbo Sedan with no factory wires cut.

Well, mostly a success. I started having problems last night with the sensors and onboard computers. Luckily, after spending the better part of this morning staring at a reccurring message on the dash that read "Engine Malfunction. Please bring your car in for service." Even after repeatedly disconnecting the negative battery terminal and waiting 3+ minutes. Also no signal from the LOC to sub after a really loud electrical buzz yesterday that sounded like I blew a fuse.

Things were looking really bad.

Then things started coming together. The engine eventually reset on its own. No idea how. The sub finally came to life after I realized I had to T-splice both channels, so 4 leads, from the Kicker 46KISLOC2 into the 2 front door speaker loops created with this connector from the AmpPro PAC:

The male side goes into the RIGHT most plug on the back of the Bose amp. The female side of the AmpPro plugs into the connector that you unplugged from the Bose. For these 2 I had to use some large clamp pliers because they were REALLY hard to snap together by hand.

Leave the wires marked "Subwoofer" as sealed dead-ends on BOTH the long and short ends. I spent way too long stupidly trying to use these leads. Leaving them disconnected will leave the factory Bose sub deactivated.

Then connect the 2 whites to the 2 corresponding whites and the 2 grays to the 2 corresponding grays. This closes the connection to the 2 front (non-cowl) door speakers, allowing the Bose to power them.

Then (or rather at the same time) somehow T-splice your 4 leads from your 2 channel LOC into those 2 closed loops from the adapter. It looked a little messy at first. I used heat crimps, but the hair dryer didn't do much so I just left them unheated for now. This was pre-organization:

Then after some careful placement:

It's more or less a standard LOC hookup, only you're doing it on the harness and not onto any factory wiring. Here's a down and dirty diagram:

Depending on your connectors, what I did was crimp the connector end with a single wire in it first, then the end with 2 wires inserted in it second. I don't think a single crimp in the middle would have worked with these connectors.

With the seat bolted back in place, the amp cover back on, and the Kicker LOC stuck on top of the cover:

Final location in trunk:

Phase set to 0. Crossover at 80. Gain right at 50% for now. I drained my battery at one point and had to jump start the car. I'm guessing that listening with the car in accessory mode might not be a good idea.

All systems seem to be back in working order this evening. Well, all but 1. Remote Start stopped working. I have no clue where to start with that, but given that I thought I had possibly destroyed a 30k car this morning, I'll take it.

 

Note: the entire seat is really easy to lean backwards once you have the 4 E-socket bolts removed. The torque is super high, but once the 4 bolts are removed, you can lean the entire seat backwards for easy access to the amp.

This accomplishes a couple of things. Firstly, you don't have to remove the lower seat belt mechanism. Secondly, you don't have to disconnect the 3 or more unrelated connectors that are attached to the seat unit from underneath. Really brilliantly designed. Or lucky, but I doubt it.

$60 between the Kicker and AmpPro.

Before:

After:

 

Remote Start mysteriously came back on its own today too, a lot like how the Engine Malfunction message disappeared eventually. All systems back to running like new from factory, additional bass notwithstanding.

I think some of the onboard computers might take more than just a 3 minute battery unplug to truly reset.

 

Flipping the sub this way and the phase to 180 seems to have helped with the delay issue. As should replacing the 20' RCA with a 7' one from Blue Jeans Cable next week.

 

This is what the final harness looked like after heat shrinking today:

The snipped blue wires from the harness were to the factory subwoofer. The other, closed off leads from the LOC are the trigger/remote and ground wires. The harness should have a ground passthru wire, and my amp is set to turn on via audio.

 

Onward with the Bose Bass Bypass (TM) project. I think the method above uses the post-amp signal, which we want to avoid. Bose appears to be bloating the bass at 50Hz, and then has a too-steep bass drop-off as you increase the volume, both of which are undesirable. Perhaps the filter is trying to be like Audyssey's Dynamic EQ, altering frequencies at different volumes (which can be OK if correctly implemented AND applied). But IMO Bose's implementation somehow ends up sounding more like Dynamic Volume, which uses compression (AKA Night Mode), and that is definitely NOT what we want from the bass signal in our 3s. Maybe someone in marketing back in the day convinced the engineers that the system had to compensate for road noise or not vibrate the cars to pieces at high listening levels. Good intents, arguably, but bad outcome.

So my next approach will be to use this green connector from the AmpPro package, which we'll call the B plug to match Mazda's nomenclature, to tap the pre-Bose signal from the head unit at the amp:

On this plugged in B harness, while playing some music and connecting the leads, I mapped out that the 2 Brown and 2 Orange leads are the front right and left door speakers, respectively. The 2 grays are the center speaker. And the white, green, and purple collectively are the 2 rear tweeters and another speaker I don't think we have.

There are 3 channels (inputs) that are NOT powered by the B plug: the 2 front tweeters, the 2 rear doors, and the 2 cowl woofers. Since we know the rightmost, black, 8-pin plug from earlier runs ONLY the subwoofer and front doors post-amp, one can therefore deduce that the black, 16-pin plug on the far left powers those 3 channels (we'll call that the A plug). This could be useful for someone wanting to tap only the rear doors. I ruled this out because the front doors may have a stronger signal, the A plug harness from the AmpPro only has open leads to a single speaker, a rear door, so I'd have to hunt down the second door and would be risking snipping the wrong wire, and finally I figured tapping the rear speakers might lead to more of a delay in bass arrival than the fronts. No idea if that last part is true or not.

I'll still use the black, 8-pin plug from the $35 AmpPro speaker harness kit (we'll call that the C plug) in order to leave the factory subwoofer installed but disconnected. That way, if/when it's time to sell, I'll just unplug the sub and modified C and B plug harnesses, re-insert the originals, and be on my way.

More to come. For now, I'm going to finish building the main B plug harness. This time I'll run about 5-6 feet of speaker wire from the 4 Brown and Orange leads to an AudioControl LC2i PRO in the trunk that I may apply with 3M velcro to the side of the sub. Then a quick jump to the amp/sub with an RCA adapter.

The goal is to accomplish the following:

1) Disable the crappy stock subwoofer that rattles the deck more than its own cone in the sedan.

2) Leave the factory subwoofer and all the speaker wiring intact.

3) Tap the pre-Bose-amp-processing signal.

4) Compensate for any weird 50 Hz peaks, crappy Dynamic EQ implementation from either Bose OR Mazda, and fix any impedance discrepancies between the powered sub and Bose amp with the better LC2i. I believe a LOC can be skipped completely if you simply want to connect your speaker wires directly to an amp from the harness, but I prefer adding at least some basic correction at this point.

Pictures to come after more heat shrinking...

 

What's going on with the "rear center," aka subwoofer, in the sedan? Is it a non-traditional composite speaker of some sort with the smaller speaker on the left?

 

What's going on with the "rear center," aka subwoofer, in the sedan? Is it a non-traditional composite speaker of some sort with the smaller speaker on the left?

I think those are just completely separate speakers, with the sub being a typical driver. I assume that smaller one on the left is used for the warning chimes you get with rear cross-traffic alert and rear parking sensor beeps.

 

Connecting a Rockford Fosgate 3sixty.3 LOC after the amp will net you a better result and allow for fine tuning of all channels.

I have a thinline Focal 10" sub and Focal 165 Flax speakers. Sounds amazing.
CK

Edit.. oh and you can run the LOC to a second more powerful amp and really have some fun with the system.

 

I may do that if I decide to upgrade any other speakers, but for now I'll likely settle on the line-level from the B harness at the amp, pre-Bose processing, to the LOC. Here's the final harness with the 4 speaker leads that feed into the LC2i PRO:

I got nervous about there possibly being a pre-Bose, high crossover applied to those tiny 3.5 inch front door speakers, say 100Hz such that they would not receive much bass below that frequency, so I tapped the Bose mono factory subwoofer signal to compare. TBH I think this 2 channel tap to the front doors from the h/u is only marginally better. I still have to tune it (not sure how Accubass works yet), but given the only minor difference between the factory sub signal and the full range, pre-Bose signal, if anything I'd be tempted to downgrade and go line-level straight to the aftermarket amp/sub and skip any additional processing.

 

Couple of conclusions and tuning suggestions for folks looking to go a similar route with the AmpPro speaker harnesses and AudioControl LOC to add ONLY a subwoofer to the 2019+ 3s with Bose (w/ cowl woofers and Bassmatch). I'm really happy so far with the results of the tap and the output and sound of the Rockford Fosgate Punch P300-12T.

I'm guessing my opinion would change if I swapped out the cowl and door speakers and added a 3rd amp. Part of the issue there is that I think the cowls will be a pain to swap out. And whether it'll be worth swapping out the 3.5 inch, full range door speakers remains to be seen. Also I think the system is drastially improved by disabling the factory Bose sub and swapping in a powered sub.

1) Use the black (right), 8-pin C harness to leave the stock sub disconnected. This harness is correctly labelled. Simply close the loop on the front door speaker leads and leave the sub leads disconnected.

2) Use the green (middle) B harness for your 4 leads from the front door speakers (Orange and Brown). This harness is incorrectly labelled. Tap the Orange and Brown loops to feed your 2 channels into the LOC.

3) Lower the head unit bass to -5. This will reduce the load on your front cowls, thus reducing bass localization from the front and possibly improving mid base output. It's also a better starting point than 0 because it will allow you to raise it later as a fine tuner. Home theater subwoofer calibration is more or less done the same way, where you want Audyssey to set your sub at about -8db as a starting point so that you can increase it 3-8db and run it hot from there.

4) To set gains on amp and LC2i, start with amp disconnected from the LC2i. Play audio. Crank master volume on head unit up to +/- 75%. Raise gain on LC2i bass channels until the "Maximized" clip light blinks, then back off the gain a hair. Lower master volume to listening level. Set amp gain to zero and then connect it. If you want a boost, raise the gain on your amp up to 25% or less. Lower the sub's built-in Low Pass Filter (LPF) crossover to around 80 Hz (lowering it should tighten the bass by excluding more higher frequencies from reaching your sub).

5) Turn it up!

 

I take back what I said about Centerpoint. Just can't get it to complement the other speakers. It seems to phase out the aftermarket sub somehow, but I don't think it's a phase issue since changing the sub polarity back from 180 to 0 increased SPL output by 5db. Either way it sounds better and has more mid bass punch with Centerpoint OFF.

 

A few changes since my initial impressions. I decided to go back to hooking up the subwoofer using the signal that used to go to the 9 inch driver in the deck. Now I can still play with the fader, which had removed all the bass when I panned to the rear since I was only hooked up to the front speakers. Man Bose is weird. I think I would have had to sum the front and rear doors, and that's way too complicated just to get a sub signal that's already right there on the first plug of the amp.

So, onward. My plan is to install a Rockford Fosgate 5 channel amp that will power 2 Hertz 1" tweeters, 2 Hertz 3" mid range drivers, and a dual 10" JL Audio sub. I'll use the original C plug to feed the JL Audio and two 3 inch drivers, and hopefully work out which wires on the A plug are for the front tweeters.

 

Hey man, I first want to say thank you for this post. I have a good idea on what I am going to purchase. I think I will follow what you posted above. I am not sure I follow you on "grabbing signal from the sub/amp that is right there at the deck". Does this mean I can just get adapters that will plug straight into the connector that is removed at sub in the trunk? Or at the amp using the 3pc harness?

Hoping I can get a response on this. Much appreciated.

 

So it sounds like you changed back to actually connect the blue wires, as those are for the original deck driver, is that correct? in that case, does one blue wire go to each wire for the LOC? (4 blue wires and 4 LOC wires). Then, I would connect corresponding grays and whites together to ensure I don’t kill the door speakers? I’m hooking up the same system (Punch P300 with Kicker KeyLOC) and just ordered the PAC wiring kit. Currently everything is wired, including the LOC, just waiting for the wiring kit and connecting that should hopefully be a breeze.