wiring 4 channel amp

Ok I'm new a this car audio stuff. I have just bought a 4 channel pioneer amp 680 watts(its an older amp) and I'm confused on how to hook up the speaker it is an 12'' sony xplode 1200 watt. The amp is bridgeable and i can get movement out of it but it will not follow the bass of the radio its more like a heartbeat  hit every three seconds or so how would i go about wiring the sub up thank youDane Kilpatrick

Common 4ch amps wont bridge full power to 1ch for one (SVC) sub. 4ch amps are not designed/tested for modern sub use. 4ch amps usually have a 4ohm minimum rating when bridged. There are 2 ways I can think of where a exception may be made. 1.- two 4ohm SVC woofers   2.- one dual 4ohm DVC sub. You probably need all four inputs connected so use "Y" splitters if your amp dosnt have a 2ch input selector. Im picturing your wired (+)ch3/RL to (+)SUB and (-)ch4/RR to (-)SUB. Thus only using 1/2 of your total available power. To make the best of what you got, bridge the rear outputs for your sony and run some highs in stereo off the front outputs. Make sure the amp is in good condition too. That heartbeat may be a signal input fault. Lemme bust out my wiring diagram.... This is what I do for FUN!

Your amplifier is broken.  It has one or more shorted output transistors.  If you have a digital volt meter and are willing to do a little footwork, I can help you remove the shorted components so you can use the other 3 channels.  Or in your case you can still bridge the other 2 on your woofer.Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB