When markers/headlights/brake lights engage RPMs drop by a few hundred. When I had my system hooked up when if the sub hit hard enough the car almost shut off.

 

Don't guess. Take it to get tested. With a big enough draw you can damage an alternator.

 

Start the car and pull your negative off... if it dies then alternator is 100% bad... if it continues to run but barely (especially with accessories on) voltage regulator is shot... and requires either a rebuild or replacement.

 

whats the amp size in the alternator how big is the sub and are you using a capacitor? and I agree with CIVC2FAST check that and let us know.

 

Not running a sub any more, i believe it's a 70 amp. Could this be a reason for me to not get a good reading off of a sensor?

 

what sensor are you talking about???

 

TPS