Car Stereo Amp Turns On and Off By Itself

frustrated in car
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Why would an amp turn off by itself?

There are a few different reasons for an amp to turn off by itself. It may be going into “protect mode,” which is an automatic shutdown feature that’s designed to prevent the amp from suffering further damage. It’s also possible that there's a problem with the wiring, the amp could be getting too hot, or it could even be faulty and in need of replacement.

When a Car Amp Goes Into Protect Mode

Protection mode is a somewhat complex subject since there is a lot of variation from one car audio amplifier to another.

Some amps have LEDs that light up when protection mode has been activated, others don’t, and some even have multiple LEDs, each of which indicates a different type of fault. In any case, if your amp is installed in a place where it is difficult to see, the protect light may be on without you even knowing it. So before you do anything else, you’ll want to locate your amplifier, do whatever is necessary to gain access to it, and then check it for a warning indicator. If it has a protection mode LED, and the LED lights up and stays lit, then the amp is in protection mode.

If your amp is entering its protection mode, either as soon as you turn it on or at any point after that, then there is a somewhat complex diagnostic procedure to follow. The basic idea behind diagnosing an amplifier in protect mode is that the amp may have been installed improperly, it may have overheated, there could be a problem with the wiring, or you might have a problem with one or more of your speakers or subwoofers.

For instance, a grounded out speaker can cause an amp to enter protect mode, at which point it will shut down.

Amplifier Wiring Problems

If your amp isn’t in protect mode, or there’s no way to tell because it doesn’t have an LED indicator, you might have a wiring problem. For instance, if your amp’s turn on wire is connected to your head unit’s remote antenna wire instead of its remote amp wire, it may shut off whenever you change the input from the radio to the CD player or anything else.

A bad fuse, or any loose or poorly connected power or ground wires, can also cause an amp to turn on and off at random.

Some older vehicles that have been updated with modern head units and amps can also present unique issues. For instance, some older vehicles are wired for both constant power and memory keep alive functions at the head unit, but the existing wiring can’t provide the correct amperage to a modern head unit. In situations like these, you may find that the head unit shuts off and comes back on when you start the car, but the amp doesn’t turn back on or never turns on at all. The only fix for this type of wiring problem is to run a new wire of the correct gauge from the battery or fuse box and fit it with a properly sized fuse.

Amplifier Heat Problems

Whenever an amplifier is on and working, it generates heat, which is why installing an amp in a cramped location with poor ventilation can lead to problems. If an amp doesn’t have adequate ventilation, it can overheat, which may cause it to enter protection mode or simply stop working. This may be a temporary problem, in which case the amp will come back on after it has cooled down, but overheating can also lead to a permanent failure.

If you find that your amp is installed in a location where it’s getting too hot, you’ll want to move it somewhere else. You may have caught the problem in time to prevent lasting damage, but there’s no way to tell other than simply reinstalling the amp in a location with better airflow, and then waiting to see if it fails permanently or not.

When All Else Fails, Replace The Amp

Whether or not the amp is in protect mode, there’s always a chance that it has simply failed. In that case, the only way to stop it from turning off on its own is to replace it. Of course, there are a lot of reasons an amp can fail, and failing to address those underlying issues will often result in the new amp failing as well, or not working properly from the very beginning.