Subs going off the hook

Most of the time this is caused due to your RCA's from your head unit. Either your head unit itself had a bad ground or another problem causing this. You can try taking a piece of wire and touch the outside of the RCA's ground point and touch the other end of the wire to the bare metal of the amp or to the power ground and see if it quits. Also unplug the RCA's and see if the thumping stops. Then you know it's the RCA's. If it does'nt stop make sure your amp is properly grounded. Try and remember if you had any problems before the thumping like the music cutting in and out, lights dimming or anything. The amp worked fine before so if it started doing this out of the blue than it's the head unit or amp. Once you rule out the RCA's, (head unit) then move on to the amp and as I said check the amps ground. If thats fine then it's your amp internaly having a problem. I've repaired numerous amps with this problem. Each amp can and will have different reasond why this happens and some have the same problem. It could be in the power supply section or in the output section of the amp. Sometimes it's the bias resistors in the amp. You don't know til you start checking. If you ever need help, I own a small business called Mark's Car Audio & Amp Repair, 727-247-5779 hours Mon-Fri (9am-6pm) Sat (10:30am-3:30pm) I have over 20 years experience and I'm the cheapest amp repair or any electronics repair in the USA. I also help people over the phone or through video chat or just chat using Skype to walk them through testing an amp out for the problems. It helps if you have some knowledge of electronics but if you don't it's fine. I'm currently working on a DVD teaching car amplifire repair made easy. It's for people who don't know anything about electronics. Also there's a section for that shows you how to just jump right in and start diagnosing an amp without learning some basic electronics first, which is in the first section of my DVD. I find allot of people who just want to jump right in. I teach this part in a way that is safe and understanding just as I do when I help a person through video chat. I am very busy with helping and repairing so if you contact me by phone and I don't answer please leave a name and number so I can return your call.I usually answer but I might be in the middle of something where it would be hard for me to stop. Thank you and have a nice day.

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RCA IN BACK OF RADIO IS BAD I had same problem try a other radio that fix mine

I just fixed this same problem...it was a bad rca cable..when i pulled out the head unit and banged the two rca's together they made the subs hit. I thought it was my amp dyin, cuz i had good ground and figured the 6 years finally put its toll on the amp. I realized when i was rocking out and hitting my steering wheel that my subs hit when i banged my wheel and dash. Nick

I agree... make sure your amp has a good heavy gauge wire for the ground(and power for that matter),make sure the ground wire connection to the body from the amp is clean(bare metal, no paint or rust) and tight ,and make sure your battery-to-body ground under the hood is good too. If you are not sure take a piece of 8 or 4 gauge wire and make a new ground directly form the negative terminal of the battery to the chassis of the car. this will ensire your grounded well...

I will agree with the first solution posted but you can also start checking values with an ohm/volt meter, a digimeter, I would start by checking values of the MOSFET Transistors, If you get more than a couple of bad reading then you got more of a problem than its worth to try to repair it unless you know your stuff in this field, but if you only got like one bad valued transistor you can isolate this circuit and see what happened to make this transistor fry like bacon then replace those parts as well I will give it an 80% chance that you need new amp but what do you have to lose, it doesnt work anyways :0)

Your ground is the problem here, try moving your ground to a different spot or try double grounds