Factory Stereo, electrical issue? Stereo issue?

[WigglesTheHoly]

So I have a factory am fm stereo in my 78 that I decided I needed rear speakers instead of the single dash speaker.I modified a front speaker connector off another truck as I do not have a factory rear speaker plug. I made new pins for the blank spots in the plug wired it up even heat wrapped the cables to make it look nice and not a hack job. I plug the speakers in fire up the truck turn up the stereo and...nada from the back. I was only getting sound from the front speaker. perplexed I checked the connections and everything looks fine. I pull the wires out of on the speakers and dropped it on accident the ground wire touched metal and boom my rear speaker that is still plugged in starts rocking.... so I plug the speaker back in and ground the ground wire on that speaker to the truck boom both start working...... Bad ground I thought. I shut the truck off and then turn it back on....Nothing out of the speakers. I de-ground the back speakers from the truck and boom sound from the front.. I tested it again same result...


what the heck is going on?