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Common Car Amplifier Problems and Solutions

Many car amplifiers are incorrectly diagnosed and sent in for repair/returned because of incorrect hookup. Sometimes the amp itself really is at fault. Here are a few common problems and what can be done to troubleshoot, as well as fix them (my fixes are the most common. They are not definitive in any way. Your amplifier could have a completley different problem, though it is unlikely):

Problem: Amplifier does not turn on.

Solution: Rule number one in amplifier hook up is to make sure the amplfier has a good ground. This means that it is secured to bare metal that is clean, rust-free, and tight.

Is the remote wire hooked up? Be sure it is, and that it is hooked up to the blue wire w/white stripe coming from the head unit, NOT the solid blue wire.

After that point, if the problem still exists, you're probably looking at bad parts in the PSU (power supply unit). The majority of the time, it's because mosfets are blown. It is never a bad idea to try hooking up the amplifier in a different car or taking it in to be tested just to be sure. Sometimes you can open the amp up and find physically fried components. For space constraints, I'll leave it at that.

Problem: Amplifier goes into protect.

Solution: This can be caused by too low of an impedance from the way the speakers are wired, and sometimes a poor charging system (if the amp goes into protect when the volume is turned up).

Otherwise, it's likely that the output transistors failed. That's the most common cause for an amplifier to go into protection. With no power applied to the amp, grab a multimeter, set it to ohms, and measure the resistance between the output transistors terminals. You should find none that have anything close to zero ohms between any of the terminals. If you find one or more that read ~0 ohms between therminals, they need to be removed from the circuit and checked. If you have several in parallel, it may seem as though the entire group shorted, but generally one fails and the others are OK. Of course, when you have one defective transistor in a group of parallel transistors, you must replace all of the transistors in that group. Open or broken emitter resistors can cause an amp to go into protect. If you don't find any shorted outputs, make sure there are no broken terminals on the emitter resistors

Problem: Amplifier is getting very hot/shutting down.

Solution: This is normally a result of the gains/input sensitivity being set too high. In addition, a lower impedance than the amp is rated for can cause this problem (and in the case of a lower impedance, it can cause permanent damage). Make sure your gain isn't turned up all the way, and that there is at least a bit of dial space between the max and where it is currently set. Be sure the speakers are wired to an impedance the amplifier can handle, and that the speakers are in good working order.

If the above have been met and the amplifier is still overheating, the best thing to do is add external cooling fans. PC fans work great, and I suggest getting the 3-5" models. They can be hard wired to the car's electrical system and a simple switch can be wired inline to turn them on and off.

Problem: Amplifier's volume turns down.

Solution: Many new amplifiers have protection circuitry that will limit the volume if they begin to get too hot. In this case, you would want to refer to the above problem for the solution.

Problem: Amplifier keeps blowing fuses.

Solution: This is usually caused by shorted output devices or power supply rectifiers. I'll refer you to the solution for the amplifier going into protect as it is basically the same thing, and is usually the root of the problem 95% of the time. Beyond that, it could be a shorted filter cap, some sort of short across the power rails, some short across the output, or shorts across the primary,. And, let's not forget loose hardware (any missing screws or nuts? A loose one under a pc board can short out most anything.)

Problem: Amplifier has intermittent or no sound.

Solution: This basically comes down to two troubleshooting steps:

  1. Try connecting a portable CD player to the RCA inputs (via headphone to RCA cable) and see if you get sound. If you do get sound, then the RCA cable from the head unit could be bad, or the head unit's RCA outputs could be fried or not turned on.

  2. Try hooking up a known-working speaker. If the speaker works, then chances are the ones you have are blown. Press down on the speaker cone of the likely blown speaker, and if it scratches, it's definitely bad.

Again, if that doesn't solve the problem, there is definitely a problem with the amplifier itself. Usually one of the output devices is to blame (seeing a consistency here? ;) ).

Problem: There is alternator whine or noise through the speakers.

Solution: This is another classic example of a bad ground. You must have a good ground connection. If the ground has been checked and is not the problem, a noise suppresor might be necessary. You can find one here.

Admittedly, some of my solutions are not for the novice, but I thought it would be good if they had an idea of what is actually wrong with their amplifier. If the problem you are having is not listed here, email me or engage me in the TechLore Forums.

Discussion:    Add a Comment | Comments 1-25 of 48 | Latest Comment | 1 2 Next »

September 24, 2008 2:37 AM


June 24, 2009 10:49 AM

my amp seems to be working fine [only the green power light is on/not the red protect light] but NO sound comes through my sub.. but my back two interior speakers still play music/whereas my front speakers don't

*and the music gets all scratchy unless i change settings to play through rear speakers only

View unverified member's comment - posted by Dags

April 18, 2010 2:19 AM

what could cause an car amp to turn on and off at the same time?? it won't stay on constantly, any one at there with a solution

View unverified member's comment - posted by wrighty2020

May 17, 2011 11:44 AM

I have a 2000w crunch amp 2 15' cvr kickers n an soundstream epicenter
I get sound n everything from my subs but I get some really nasty bass like if the subs were to burn out.....my cuzin has the same sound as me n his sh+t sounds awesome any idea wat it can be?

View unverified member's comment - posted by jason L

October 27, 2011 7:22 PM

I just set up my new 1200 watt amp&sub it works fine but when it is on my front window wipers dont work and when it is off they work! im puzzeld can anyone help???

August 24, 2012 6:48 PM

Hey I have a 2,000 watt amp and i have been useing it before for my subs and recently i put it back into my truck and it works good with a low volume but once i turn it up the woofer starts going crazy and i know its not the woofer becuase i put the woofers conected to another amp and it works perfct. So what can be wrong with my amp?

September 16, 2012 6:31 PM

i have an american pro amp its like 800 watts and it goes into protection mode when turned on..i get a second of bass or sound but thats it...if i turn the switch on and off a few times i may get 3 to 4 seconds of sound but it goes right back to protection mode,, anybody know whats wrong??

View unverified member's comment - posted by ActorMichaelHarrison

View unverified member's comment - posted by cockboy

View unverified member's comment - posted by n1gger

View unverified member's comment - posted by dood2493

May 24, 2013 8:39 AM

I have a Sony xplode 222 running my mids and highs and a boss audio 2.500 running my subs, it's s cheap setup but sounds suprisingly good , my problem is that my amps lose powr for no reason . Then out of nowhere they'll come back on. I've ran a 4awg power wire to a distribution block and good ground , I'm stumped any advise would be greatly appreciated

May 31, 2013 4:46 PM

Just bought a new amplifier, everything is wired up correctly but I'm still having problems, as soon as I tick the car over the red light flicks on and off and nothing happens? When I Turn the car back off, the green light comes on then off. Red light comes on and off and then both come on and fade? All this happens with in 2 seconds? Does anyone have any ideas? Really need to sort this out its driving me nuts! Thanks

June 27, 2013 2:57 PM

I have a JL Audio amplifier 300/2 that I had on my truck , it turns on but gets hot and it barely moves my subs I don't know what's wrong with it.

View unverified member's comment - posted by crashcourse

August 20, 2013 10:09 PM

Can someone help me out? I have 12v from my battery but when I check it at the amp it only reads around 9v, which is not enough to push the amp. Does anyone know what would be the problem for this, or what I could do to fix this? It was working before it just stopped working while I was driving. The green light is on and the red light is flickering but no sound from the subs, it is a kicker cx 1200 if that helps at all.

September 15, 2013 12:18 AM

Ok hooked up a 600w amp today and I have checked EVERYTHING. The radio will randomly just shut all sound off. When this happens I can not control the radio at all. No volume or changing song/ station, so when this happens there is no sound for a few seconds or minutes and it is random we can go 30 minutes without a problem or it can happen every 5 seconds. Please help.

November 25, 2013 3:54 PM

Can some one answer my question. My amp and speakerr have been wrking fine but as of late. When music comes on I have a lot of feedback frm my amp and the bass sounds muddy and not clear. Is this a ground wiring issue

December 9, 2013 12:00 AM


December 9, 2013 9:13 AM

Check the ground, make sure you have bare metal connection. sand the paint off where you are grounding to and make sure all connections to amp are tight, it sounds like the vibration is causing the problem.

December 9, 2013 10:25 AM

Thank u very much for your help JD but that's not the problem. you see my amplifier and my radio are sitting on the bench. I was bench checking before I installed. I bought the amp used at a pawn shop in Houston. I really believe there's component burned out inside amplifier. The more I push it the quicker it shuts off. Comes right back on for a split sec if volume is up and stays on longer if volume is low. Also found solder shaking around in the cabnet. I need to know what component would give those kind of symptoms, and will a multi meter work to test it?

View unverified member's comment - posted by Brady b

Discussion:    Add a Comment | Back to Top | Comments 1-25 of 48 | Latest Comment | 1 2 Next »

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