No sound from front speakers

[lizardking100]

I recently reacquired a '99 uzj and I have been working to iron out a few bugs on this 14 year old vehicle.

The PO installed an aftermarket head unit using a ready-made adapter (no wire splicing). The front speakers weren't working with this old system. I fiddled around with it and even pulled the PS front seat to check on the OEM amp (no apparent problems).

I'm not much of an audiophile and I really can't stand the look of tacky displays and hacked look of aftermarket head units, so I ordered a used OEM head unit off Ebay. Tonight I plugged it in and it works perfectly, except I still have no sound to the front speakers.

Has anyone hear experienced this phenomenon?
Did a "channel" on my amp fail?
Any ideas/fixes?

FWIW the harness to the head unit looks to be in good shape.

 

[yournamehere]

The factory amp is probably still in use. (Under the passenger seat) I'm willing to bet the output on the head unit is fine but the output on the amp is bad. I say this because my front right channel just stopped working. I got a new head unit with the same type wiring harness and the front right channel still didn't work. We bypassed the factory amp and all was well.

 

[ToyEvil]

I had this problem recently with an 04. Turned out one of tweeters shorted out from contact with metal. Found this after removing door panels etc. All 4 front speakers were out. May be different system with 99 model.

 

[ogsuv]

I think amp croaking would be rare along with a short of factory wiring. My guess is a dead speaker or modified wiring grounded somewhere. I might meter the speaker wires At the amp or flip a coin and pull one of the doors apart