I was trying to find info on adding subs to the car and was not finding anything helpful on what wires to tap and all the controversy with the Bose system made it a bit difficult. I followed a prior write up and it was wrong so I decide to do one myself. So here is how to simply add a sub and amp to the trunk of the M45. It turns out it was surprisingly easy to get the power cable from the battery to the amp. Once you get your amp adjusted you can adjust the bass using the stock audio controls.
I am assuming you know basic audio install and are looking for what to tap and where to run wires in the car and all the usual do at your own risk stuff.
1. Locate the amp in the trunk by removing the four clips and flipping the top portion of the cover down in the back of the trunk. You can completely remove it but it is not necessary.
2. Now is when you have to decide what you are going to tap into.
a. Rear speakers and adjust bass out by pulling sound to the front. (I chose this route)
b. Front speakers and adjust bass out by pulling to the rear.
c. Existing sub. The controversy on this is that bass decreases as volume increases.
Rear Left Speaker + light green -black w/ yellow stripe (far left)
Rear Right Speaker + light green – black w/ purple stripe (far right)
Front Left Speaker + blue – black w/ white stripe (2nd from left)
Front Right Speaker + brown – black w/ red stripe (2nd from right)
Remote turn on blue w/ black stripe (center single wire)
This is the white and gray harness for the stock sub.
Sub + brown w/ white stripe – brown.
3. You can use a Line Out Converter, or as I did cut an RCA cable in half and splice directly into the input you chose. Choose which speakers your are going to use and carefully strip the wires back and then splice in. Soldering is the recommend choice here.
4. The best ground that I found was in the right side of the trunk under the side cover. If you pull it back you will see where two wires are already grounded there. I figured if it was good enough for the factory it is good enough for me. (green dot in pic)
5. To get power from the battery to the trunk the best route is as follows. On the left side of the trunk by the strut you will see some foam this will lead through to the back seat.
Push the seat to the side and you will see through to the trunk. Feed the wire through here. You can see the blue power wire at the bottom of the picture.
Unclip the panels on the door sills with a little tugging. Run the wire along here to the fire wall. From under the hood on the driver’s side you will see a large bundle of wires going through a large grommet. Pull the grommet out and feed the wire through.
Run i long the firewall and connect to the battery.
6. Button everything back up and you are done.