Finally got satisfaction from the JBl system!

Haven't been happy as many here dealing with the inadequacies of the JBL system in my '19 1794 so over the last couple months I've worked on trying to take it over the top. I started with adding a powered sub to the system by installing the PAC Audio interface and a powerbass sta-10. This certainly added in the thump the useless Jbl sub wasn't providing but I still was not getting the volume from the system I wanted. So next step was to add on an amplifier. Replacing the speakers was a consideration as well but I wanted to see if some good power would do the trick first. I got a Pioneer GM-DX874 4 channel amp which is way more than enough but it handles lower ohmage and I figured if the speakers couldn't take it then I had an excuse to replace them. . I purchased the jbl harness from James at tech12volts and dug in to how I would have to make connections. I was not gonna utilize the factory sub as I had the powered one in already so that's why I opted for a 4 channel amp. The use of the PAC interface required different steps then Jame's instructions that come with the harness as it is situated before the JBl amp as opposed to downstream from it like the fix86 operates and I had to trial and error with the harness to sort it all out. I also initially had wired in the center speaker as well but because of the bridged hookup it was getting way to much power and I didn't want to mess with adding on a crossover or resistors to tame the power and frequencys especially after I unhooked it and realized I didn't need it. Now I could have just put in a head unit and ditched the factory amp and utilized the harnesses but I already had the PAC and powered sub in so I decided to go this route. It'll run you outta the truck now! I gleaned a lot of info from this site and have seen the frustration about how to deal with the JBl system so I'd like to pass on how I did it for anyone else who may get something from it.

First the parts and devices I used.
PAC Amppro AP4-ty12
Powerbass sta-10
Pioneer GM-DX874 4 channel amp
JBL harness from tech12volts
Rockford Fosgate dual amp kit
Another set of patch cables for the powered sub.

The head unit has to be removed to install the PAC interface. The PAC harnesses plug into the HU and then factory HU harnesses. I then plugged three sets of patch cables to the PAC. One set for the powered sub and front and rear sets for the new amp.
I had to change the setup from the instructions James provided with the harness. Once again the instructions are factoring that a processor is gonna be used downstream of the factory amp. There are four plugs, large female and male plug and small female and male plug. I had to insert the small male plug with the yellow 12v wire into the factory jbl amp where the blue factory plug was. None of the speaker wires from this small male plug was used and taped off. I then plugged the small female plug into the blue factory male plug. These speaker leads will be utilized. I didn't need the large male plug from James harness so I removed it and only used the large female plug plugging into the other male plug from the JBl amp that's closest to the dash. (There are three plugs in the jbl amp, the plug closest to the rear seats stays in as well as the small male plug from Jame's harness). The large female harness speaker leads are utilized.


Because I put the pioneer amp under the rear passenger seat I had to run speaker wire from the harnesses to the new amp.
Here are the wire colors and utilization.
The small female plug with the yellow 12v wire(i didn't use the yellow wire from the female plug and taped it off)has the rear speaker leads, the front door tweeters and dash speakers(not the center speaker)
The purple pos and neg are the R. Rear door and tweeter. Those are run to the R. Rear channel of the amp.
The green pos and neg are the L. Rear door and tweeter. Goes to the L. Rear channel.
The gray pos and neg is the R. Front dash speaker and door tweeter.
The white pos and neg are the L. Front dash speaker and door tweeter.


Large female plug
The gray pos and neg is the R. Front lower door and gets spliced with the gray leads above. They then go to the R. Front amp channel.
The white pos and neg is the L. Front lower door and gets spliced with the white leads above. Goes to the L. Front amp channel.
The green leads are the center dash, if you wanna wire it in the pos lead ties into the pos Front Left and the neg lead goes to the neg.
Front right. But this bridging will send a ton of power to it(about 4 times the amps per channel rms rating).
Purple leads are for sub
Set your gains and crossover networks and enjoy!