Car Stereos: subwoofer, rca cables, rear speakers

Question
hello
i have a 1990 ford f150 and were upgrading from a  facotry stereo. we installed a headunit and new doorpanel speakers. it doesnt have rear speakers. we bought a amplifier and a 10inch sub. we ran all wires correctly,  rcas  are hooked up correct ground wire remote wire etc. the amp powers on fine but i get nothing from the sub. to make sure it wasnt the amp or sub i tried a different amp and sub  same thing. amp has power but no sound or anything from the sub. we checked all fuses and rca  hookups again and cant figure  out why it wont work. any pointers?

Answer
Hi Tiffany,

I apologize for my late response.  Hopefully  you got your problem figured out; if not, I hope this isn't too late to do you any good.

It sounds like you've eliminated the amp and sub as the source of your problem.  That just leaves the head unit output.  If you have some other RCA cables available, you might try switching the RCA's.  If your RCA cables are plugged into a subwoofer pre-out at the back of your head unit, then make sure the subwoofer setting is turned on in the head unit's setup menu.  You might also try switching to a different output (ie, front or rear) and see if you get any sound that way.

Hope this helps!

Brian