No sound from speakers

I just recently helped a buddy install an entire system(HU, Speakers, Subs, Amp), it worked fine for a few days then the sound started to cut out but would come back if he turned the HU off and on but as of recent there is no sound and it wont come back when he turns the HU off.

1994 Dodge 3500 Laramie reg cab
JVC Headunit
Jensen 6x9
Roadmaster 6½
Pioneer 760w Amp
2 Audiobauhn AW1251T(i think the one with flames on the basket 400w rms)

The headunit and amplifier both have power and the subs still hit just no sound from the speakers. However he is stubborn and didnt want to buy speakers or listen to my suggestions

I think it has something to do with A) Factory wiring possibly the ground or B) he blew his speakers cause they suck and he was blaring them on 45 - 50 everyday(my jvc stays around 15 - 20, 30 is MY max can go higher but might blow something).

If anyone else has any suggestions or solutions i would greatly apprieciate it.

P.S) I have installed everything in my truck(sony xplod speakers, jvc headunit, kicker subs and amp) and the subs in his room mate's jetta and both of those work 100%

if the regular speakers are playing from the headunit's builtin amp - it could be the headunit or speakers are damaged.

if the regular speakers are playing from the headunit's builtin amp - it could be the headunit or speakers are damaged.

thanx for the quick reply, the regular speakers are running off the HU's amp, but is there a way to know if its that other than switching it out?

you can hook up a dmm to it

you will have to check either the speakers or the headunit seperately to see which one it is