Wired sub . rear speaker problems

[COMMY VP 666]

firstly i have put quite few sound systems in so got abit of an idea but ......

i have a pionner deh - P5150UB

it has x3 rca out puts, 1. sub. 2. front speakers. 3. rear speakers

one one of my settings you can choose the amp is being used for sub woofer or front speakers

i do have a sub in there, but for some reason when i have that setting on for sub. the sub works perfectly but the rear speakers don't work

but when i change it to - front speakers it turns the sub off and the rear speakers back in

the cd player is new had it for years but not used. the amp is fine and so is the sub and rear speakers.

does anyone have any ideas im stumped

[Philthy]

What amp are you using and what are you running off it?

[COMMY VP 666]

its a sony amp, i think you mean rca's?

running it from the cd player (sub rcas) to the amp

[Philthy]

I meant what components are you running off the amp? Just the sub or is it the sub and some speakers?

Also, we need more detail on the amp. Model numbers would help, but at least tell us some details. Monoblock, 2ch or 4ch?

I assume you are only using the 1 amp?

[StoneX]

It'll be a head unit setting and/or you have the wrong RCA's plugged in to the wrong amps.

[holdenboy]

I think those head-units had the ability to run a subwoofer off the rear speaker outputs or something? i dont know but this may be a problem for you.

As StoneX said, double check youve got the right RCAs plugged into the right amp etc, are your rear speakers running off an amp?