Good to know.

I can't wait to get my new amp in there and see what this all sounds like.

Alright, your diagram confused the living hell out of me. The monsoon amp looks identical, except my two harnesses do not match your color coding. In fact, they're very different. One harness has 8 wires, two of which are red and black, which don't match up to the diagram you sent me. I'm assuming the red and black refer to the power and ground for the amp.

The only wires I've been able to tell for sure are the colors of the output wires to the speakers. There are so many other wires going into that amp that I don't know which ones are the input wires for the rear speakers. What I did discover is that the amp powers the front door 6.5'*, and I found the which twisted pair goes to which door. Relative to the amp, I don't know if those twisted pairs are output or input though. Both of those twisted pairs were on the harness with the power and ground, which leaves me with only one blue and green wire left on that harness, which is a single output of only bass from the amp going out.

I'll get back under there and see what else I could find. If anyone has any ideas, please let me know.

Alright, I've been cutting up wires in my trunk and here'* what I'm thinking.

How many outputs for channels are there from the stock head unit to the amp? Are there 4 or 6?

What I'm starting to wonder is if there are 2 front channels and 2 rear channels, and if the 6x9'* simply act as subwoofers. The notion here is that the amp takes the bass frequencies from the rear channel inputs and outputs those two the rear 6x9'*, and continues to output the full range sound to the rear door speakers.

This would be different than a crossover, and in this sense, all one would need to do in order to get full range 6x9 speakers would be to splice the high level outputs from the head unit to the amp and use those to run a factory amp for the 6x9'* as I'm trying to do.

At this point, I don't know if there are 6 different channels to output, or simply 4, because I have yet to find the input for the rear 6x9'*, and I'm almost done cutting **ALL** of the wires in that harness to find out.

I made that wiring diagram based on my 03', so your wiring could very well be different. You will have to do what I did and "pop" the speakers, unless someone else chimes in with a diagram for your year. One harness should be an input for the amp, and the other should go out to the speakers still. All you need to do is connect the input to the corresponding output. My wires were in twisted pairs, so you have a positive and a negative in each pair. Take a battery (probably best to use a 1.5 V battery so you don't damage your speakers), and connect the negative to the negative on the battery, then touch the positive to the positive on the battery and the speaker that the pair is for should make a noise. It won't matter if you mess up the polarity for this, it should still pop. Mark each pair of wires as you figure out which one pair runs which speaker. Now you should know which wires on that harness go to which speakers. For the other harness, I had to figure out which one was which up front. I had an aftermarket wiring harness that had the wires labeled as left, right etc. So you look at the wires for the left speaker and see which wires they correspond with on the factory harness. That will tell you what wires in back are for which speaker, and you then match up the appropriate pairs. As far as telling what wires in the pair are positive and negative, I hooked my speakers up one at a time and looked at them/felt them. When bass hits, they should move out, not in. It is hard to guess which ones are positive, they didn't seem to follow any pattern such as light colors are positive dark colors are negative, etc.

Now I'm confusing myself. I think your right about the amp splitting the 4 channels into 8. If so, that means your only going to have wiring for 4 speakers coming back. That was fine for me because I also utilized the rca outputs on the radio. Here is how my system was set up.

I used the wiring for the front speakers to power the rear doors, and the wiring for the rear speakers to run the 6x9'*. They were now running full range right off the head unit, but I also replaced my speakers with full range speakers. I then ran rca'* back to the amp, and used the amp to power the front 4 speakers. I also had to run speaker wire from the tweeters and 6.5" speakers up front to the amp. That gives you the ability to run all 8 speakers again.

Yep, that'* exactly what'* happening. I confirmed your notion by checking the color wires. The colors you gave me are indeed for the front speakers. I ended up cutting and re-connecting all wire pairs except for 3 to figure out which was which and label them. I reconnected them with butt connectors so its not too pretty, but it will hold.

So basically what someone *really* needs to do in order to run full range 6x9'* on the rear deck is to splice the outputs to the rear speakers into a high level input for a separate aftermarket 2 channel amp. Some amps have them built in, and with others you have to get a high level line converter to RCA to get the input signal, and power the rear 6x9'* off that amp.

Alright, I finally got this done, and it is a HUGE improvement.

I bought an amp off of Chris about half a year ago. Particularly, this amp:

http://www.drdetailshop.com/d300-2.htm

Its pretty underrated. I had it pushing a 12" sub at 2 ohms and I blew 25 amp fuse long before it overheated. This amp has a high level input, which means you can plug in the wires that would normally go into your speakers directly into the amp and it will amplify that signal. This made my job a bit easier since I would have otherwise had to buy a high level to RCA converter.

Whether you have an amp like mine or you're using a converter, here are the wires you need to splice. These wires go to the rear door speakers, so what you'll be doing is taking the signal and reproducing it to the rear deck 6x9'*.

Brown is LR +, Yellow is LR -, Dark Blue is RR+ and Light Blue is RR-

I'm using a pair of Kicker 6x9'* and the added depth of sound makes an immense difference.

Edit...one thing I forgot to mention. If you do remove your factory 6x9'* and replace them the way that I did, you will need to run a separate subwoofer in your car either off of the existing connections for the 6x9'*, or with a separate amplifier, as the signal for the rear door speakers have little to no bass at all.

Thanks to all that have contributed to this thread. I started this back in November and haven't been back in for a while. Thanks to Extreme for finally doing exactly what I've wanted to do for years. I'm excited about making this change to improve the sound quality and get rid of all that booming in the back. It was hell for anyone in the back seat if any music was being played even at a modest volumn, Thanks again Extreme for bringing this tread to a happy ending

Im so confused. That diagram shows four connections. But there are eight speakers. Using the 1.5 volt battery method I found 5 speakers: RR (6x9), RR, LR, LR (6x9), and LF. That leaves RF. I'm assuming the tweeters are wired to the 6.5"'*. Anyway, in the diagram it says that the Dark and Light Blue goes to the Green/Black and Green. Well I have two sets of Dark and Light Blue wires, one being the Left Front, the other being the Right Rear. Im lost, this diagram should work because I have a 2003 Bonneville WITH the Monsoon system. I got a new HU and wont work with the amp so I'm bypassing it. I have had this problem for MONTHS and am absolutely fed up with this ****. PLease help me. I can post pictures if it helps people solve this problem.

i would just run the four new speaker wires, the oem ones are small anyway. and when you get rid of the car it will be that much easier to put back