My car has the upgraded Bose system but I would like to add just a bit more bass (nothing crazy). So I am planning to add an underseat powered subwoofer while keeping the rest of the system stock--similar to what I have done in my last few cars. After investigation and reading a lot of posts from owners of other Mazdas with the Bose system, I have come across two challenges.
First, the cables connected to the Bose amp are different from those used in prior Mazda Bose systems. I found a terrific report about the Bose system wiring in the 2014-2018 Mazda 3 (2014-2018* Mazda 3 & Mazda 6 w/BOSE Full System Breakdown/Analysis). Unfortunately, while the amp remains in the same location (under the front right seat) instead of 3 cable connectors, I have 4 connectors (there's a new blue connector with 2 wires) and while the size/pin number of the remaining 3 connectors remains the same, the colors of the wires on the connectors bear almost no resemblance to that used previously. I've attached some pics of what I can see.
I saw a picture in a Mazda 3 forum showing the same 4 connectors on the current gen Mazda 3 Bose amp, but unfortunately that post had no wiring diagrams. Prior Bose systems sent a line level input from the head unit to the amp and all the signal processing happened at that box. I am guessing (hoping) that the same engineering is used in the new system and I will do some testing when I have a chance to identify which wires carry the various left, right, front, rear input signals. My powered sub can take either line level or high level inputs, but I will try to tap the line level inputs for an unprocessed signal. If anyone has already figured out the wiring configuration, I would greatly appreciate sharing of the details!
Second, even though my powered sub is rated at only 150 watts RMS (and even that rating is suspect) best practice would be to run a power cable direct to the battery. The grommet in the firewall where all internal wiring goes through is located on the left hand side of the car hidden somewhat by the battery, but if I remove the battery I should be able to reach it on the engine side. On US cars, this should be easily accessible from under the dash, above the pedal area, but my car is right hand drive, so the grommet should be accessed by removing the glove box. I've attached a picture showing behind the glove box, but access to the grommet appears to be blocked by the cabin air filter assembly.
![283]()
I have searched for any other possible entry points, for example where the clutch assembly would have gone through the firewall if this was a manual car, but I have not found any other holes that look useable. I have no idea how complicated it wil be to take apart the cabin air filter assembly so if anyone has any ideas on how I can get through the firewall (without drilling a new hole), I am open to ideas. I had ruled out trying to tap one of the existing 12v power lines but if any of the electrical experts out there can advise a safe method for me to do so, that would make this so much easier. For example, wouldn't the fuse box on the left hand side kick panel have a pretty heavy gauge wire from the battery in order to carry enough power for all the fused wires? Would it be possible and safe to connect there given the moderate current draw of the powered sub?
Hope to share ideas and information with anyone else that is tinkering with their stereo in the CX-30 or the current gen Mazda 3.
First, the cables connected to the Bose amp are different from those used in prior Mazda Bose systems. I found a terrific report about the Bose system wiring in the 2014-2018 Mazda 3 (2014-2018* Mazda 3 & Mazda 6 w/BOSE Full System Breakdown/Analysis). Unfortunately, while the amp remains in the same location (under the front right seat) instead of 3 cable connectors, I have 4 connectors (there's a new blue connector with 2 wires) and while the size/pin number of the remaining 3 connectors remains the same, the colors of the wires on the connectors bear almost no resemblance to that used previously. I've attached some pics of what I can see.
I saw a picture in a Mazda 3 forum showing the same 4 connectors on the current gen Mazda 3 Bose amp, but unfortunately that post had no wiring diagrams. Prior Bose systems sent a line level input from the head unit to the amp and all the signal processing happened at that box. I am guessing (hoping) that the same engineering is used in the new system and I will do some testing when I have a chance to identify which wires carry the various left, right, front, rear input signals. My powered sub can take either line level or high level inputs, but I will try to tap the line level inputs for an unprocessed signal. If anyone has already figured out the wiring configuration, I would greatly appreciate sharing of the details!
Second, even though my powered sub is rated at only 150 watts RMS (and even that rating is suspect) best practice would be to run a power cable direct to the battery. The grommet in the firewall where all internal wiring goes through is located on the left hand side of the car hidden somewhat by the battery, but if I remove the battery I should be able to reach it on the engine side. On US cars, this should be easily accessible from under the dash, above the pedal area, but my car is right hand drive, so the grommet should be accessed by removing the glove box. I've attached a picture showing behind the glove box, but access to the grommet appears to be blocked by the cabin air filter assembly.
I have searched for any other possible entry points, for example where the clutch assembly would have gone through the firewall if this was a manual car, but I have not found any other holes that look useable. I have no idea how complicated it wil be to take apart the cabin air filter assembly so if anyone has any ideas on how I can get through the firewall (without drilling a new hole), I am open to ideas. I had ruled out trying to tap one of the existing 12v power lines but if any of the electrical experts out there can advise a safe method for me to do so, that would make this so much easier. For example, wouldn't the fuse box on the left hand side kick panel have a pretty heavy gauge wire from the battery in order to carry enough power for all the fused wires? Would it be possible and safe to connect there given the moderate current draw of the powered sub?
Hope to share ideas and information with anyone else that is tinkering with their stereo in the CX-30 or the current gen Mazda 3.
