Stereo & Electronics - audio troubleshooting

I'm having trouble getting my system to work. I put in new amp, sub and deck today, everything works fine except for the sub. The amp turns on, but theres no power to the sub. I checked everything, tried a new set of rca's...nothing. I'm getting no voltage at the amps speaker terminals.

I've narrowed it down to a problem with the Rca outputs on the HU or the amp having a problem.

Does anyone know what voltage i should be getting at the rca outputs and the speaker terminals?

Have you turned on the sub output? Many aftermarket head units have internal switching for the sub output that is off by default. You turn it on though a menu or some sequence of keys on the head unit - check the unit's manual.

yeah everything is on. does anyone know what voltage i should be seeing out of the rca's?

1-4 volts ac, with music or a sweep playing, volume dependent

I'm only seeing .25v out of two different headunits.

im not sure the voltage but a good way to find out if its the amp or deck is to power everything up and disconect the rca's and tap them together or touch them with your finger and you should hear a thud or some distortion thru your sub