Subs go crazy after car shuts off

Where are you getting remote turn on signal from?

I say its probably the Hifonics amp having poor ground loop as they are not very good amps to have unfortunately.   The noise or whatever you are experiencing is a result of sudden voltage drop causing a ground loop.

I suggest you do this...

• take your Hifonics amp out and get another amp and hook it up to your subwoofer and give it a run.
  
• Turn the ignition and run the engine, turn the stereo on play a track then turn it off;
  
• Turn the engine off and repeat the process;
  

If the issue is gone, then most likely its the Hifonics amps, they are not as good as the old Hifonics 'power from the Gods' era, from memory, they were made by Zed.

My money is on your amp mate!

If you have good power/ ground/ remote, it should not do this, check your ground as well before you take the Hifonics amp out.  Use a multimeter to get resistance and voltage reading.  Remember, power travels from negative, to positive hence the 12v neg ground term. :graduate:

I say take the amp out and bench test it. if the issue remains then most likely it is the amp as they have poor RCA grounds, there is a reason why you pay cheaper price for amps these days.  Hifonics comes out from the same factory that now makes, MB Quart, which is now owned by MAXONICS.  (Don't know where they hail from but the company is known to churn out entry level gear at the cheapest cost to the consumer. Its main consumers are car dealers who would like to sell the car with a blue tooth radio so they can state its got an aftermarket blue tooth radio. Its not for car audio freaks like me and personally I will not buy the stuff, brand new or second hand. Its a like of gift you give to your ex or your somebody you don't like at Christmas! :laugh:

Jake12689 said:

Yeah I think it might be but I have a hifonics in my truck and I have had it for a few years and it never does any of this. I will have to get a diffrent amp to try but what amp would you recommend? I'm looking for 2000 watts as I'm going to get bigger speakers.

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that hifonics is closer to 1400 watts. literally garbage for the money if you never had anything better. wolfram has a decent amp around 250.  Taramps md 3000.1 is good too.

back to the main issue.... your remote wire situation needs to be explained. LOC is still on when the car is off and its still putting random noise signal through to the amp would be my guess.

still to make any kind of noise, the amps would be on so i'd check the remote connections to the amp and make sure it fully turns off.

I have had a amp go into protect and a sub go crazy even on volume 0 due to a bad sub rca on a deck. 

I remember about 10 years ago my buddy had to use one of those channel out converters to be able to use his OEM headunit and it did the same thing. I admit I have no idea why it did this, but I borrow his car one time and just shut the car off and it did the same thing, just made a huge random noise. He said the speakers in his car continue to have power after the car is off. Either way, he added a basic toggle switch to his remote wire, and installed it in a coin hideaway storage under his steering wheel. I have since installed a toggle onto my remote wire just because it's a very convenient way to just turn off the system. As to whether or not it's healthy for your amp, I don't know. I've had the same amp now for 5 years with no issues. But if it was the only way I could use my system, I would try that.

Did you ever figure out what was making the noise happen? I'm have the same issue. I've tried everything I can think of.