Confusion on aftermarket sound system

[Cherryred98]

I have a 98 extended cab 2 door. When I bought the truck it had the stock stereo in it with aftermarket speakers. I swapped out the head unit for an aftermarket one (the usual I went and bought an adapter from autozone and hooked everything up)
The rear speakers haven’t worked since I bought the truck, after further investigation the truck appears to have had a full system that was installed by a shop I think. It has aftermarket rear speakers ( that for whatever reason don’t work) and after market front speakers. A 4ga power wire that runs to the back wall (under the rear window) that splits to two 8ga wires (with relays) one 8ga goes to (what was) a 2 channel amp for subs and the other goes to a other amp with a whole bunch of wires I think somewhere along the likes of 12 or 16 speaker wires. I’ll post pictures. I had a amp hooked up with subs (on the 2 channel side) but I can not figure out how he had the amp setup for the speakers as there is only 4 and it appears to have had tweeters that he removed along with the amps and subs before selling it. I’m thinking the rear speakers don’t work because there is no amp to complete the signal some how? Idk

Questions simplified
1: what wires do what for the other amp
2: can I use the stock tweeter wiring and just plug in stock tweeters?
3: why don’t I have rear speakers?

 

[Cherryred98]

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Power wire in

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RCA for sun and speaker wires for subs

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RCA for front and rear speakers


And all these wires that I am totally confused on

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[DerekTheGreat]

I got lost after reading to the point where the 4ga wire splits into two 8ga wires. If it was me, I'd rip all of that out and go back to stock. I imagine you're not going to do that, so my advice would be to start over right at the two 8ga wires, rather than troubleshoot what's going on. Have one 8ga run a four channel amp for the full-range speakers and the other 8ga for the subwoofer(s). While you're busy doing that, you'll probably find out why the rears aren't working. I imagine they're either blown or as you stated, the signal chain is open somewhere.

 

[BuiltToWork]

I got lost after reading to the point where the 4ga wire splits into two 8ga wires. If it was me, I'd rip all of that out and go back to stock. I imagine you're not going to do that, so my advice would be to start over right at the two 8ga wires, rather than troubleshoot what's going on. Have one 8ga run a four channel amp for the full-range speakers and the other 8ga for the subwoofer(s). While you're busy doing that, you'll probably find out why the rears aren't working. I imagine they're either blown or as you stated, the signal chain is open somewhere.

I second starting over. You can even re-use the old wires, but pull them all out 1st. This is my opinion only.

 

[Kran]

if i had to guess, PO disconnected the factory speaker harnesses for the rear speakers and added his own runs of wire which would probably be one of the sets of black wires with yellow fork connectors you're holding.

it's impossible to know what wires go where or how they're hooked up. only PO would know the answer.

best bet is to rip it all out and redo it how you want. or trace all the cabling