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Why Won’t My Amp Turn On?

It’s a beautiful day outside. The sun is shining and the weather is perfect. You hope into your car, ready to start your busy day, turn the radio and …nothing. There’s no sound coming from the speakers or subwoofer.

Upon some investigation, it appears that you amplifier isn’t turning on. But what’s causing it to fail on you? And is there anything you can do to fix it and make it turn on again?

Well, there are many things that can go wrong with your amplifier, some are more common than others. No need to worry though, there is a solution for almost every problem.

To help give you some insight, we’ve put together a quick guide on everything you need to know to fix the problem and start jamming again in no time.

Disclaimer

First and foremost, we need to make one thing clear: An amp that’s in protect mode and an amp that’s not turning on are two different things, but are closely related.

If your amplifier turns on but it’s stuck in protect mode (its protect indicator light up and keeps blinking or its power light blinks then goes off), refer to this article to get your amp out of protect mode.

Most modern car amplifier have a power on LED that will blink to indicate that the amplifier is up and running. If your amp has such an indicator but it’s NOT blinking when the power wires are attached, read on to find out what you need to do to get it sorted out.

5 Reasons Why an Amplifier Won’t Turn On

There are a number of different reasons your amp is not turning on, from being wrongly wired, to more complex issues like a fault with its electronics.

But some things are more common than others. Here’s a rundown of some of the more typical reasons why that happens.

1. Blown fuse

There are usually two or three different types of car amp fuses in a typical installation. So, depending on how your amp is wired into the electrical system, you can find yourself dealing with a variety of different fuses.

In cases where a power cable is run directly from the battery to the amplifier, there will be an inline fuse that can blow in addition to the internal amp fuse. In other installations, power is drawn from a distribution block with a fuse of its own.

Amplifier fuses blow for a wide variety of reasons including but not limited to: using wrong fuse size, impedance mismatch, reversed polarity, excessive clipping …etc.

So, when your amp isn’t turning on, you need to check all of these fuses one after the other. First, start by checking your amp’s built-in fuse (if it has it). If it’s intact, check the distribution block’s fuse, and then check the inline fuse.

If any of those fuses is blown, your amp won’t be getting the power it needs to turn on and drive your speakers or subs.

While it is pretty straightforward to visually inspect a fuse to see if it’s blown, we highly recommend using a multimeter. It’s the more precise way to go about it.

2. No remote turn on wire

A turn on wire is a Blue wire (typically with a white stripe) located behind the receiver. Its main function is to “wake” your amplifier up whenever the head unit is powered up.

Technically speaking, the remote turn on wire receives voltage from your vehicle’s electrical system when the ignition key is turned on. This voltage is transferred through the remote turn on wire to the amplifier turn on circuit; when the amplifier senses this voltage, it turns on. Likewise, when there’s no voltage in this wire, the amplifier turns off.

Without a remote turn on wire, your amplifier will not turn on even if it has good power and ground connections. This the reason why the remote wire should be wired correctly.

One thing to note, most receivers’ wiring harnesses also have a solid blue wire. The latter is typically for power antenna or factory amplifier turn on. So, do not get it confused with the remote turn on wire with the blue/white stripe.

If you mistakenly connect the power antenna wire (solid Blue) to your amp’s remote terminal, your amp will ONLY run when the head unit audio input is set to AM or FM radio. If you switch to Aux input, CD, USB, etc… your amp will stop working. This is because the “solid Blue wire” is a power antenna wire and only receives voltage from the receiver when AM/FM is chosen as a source.

3. Improper grounding

It goes without saying that when installing a car amplifier, the ground wire can make or break your sound system. Improper grounding can cause all sorts of problem including but not limited to dimming headlights, clipping, ground loop noise (engine whine), amp damage…etc.

Basically, what grounding an amplifier does is that it completes the electrical circuit powering your amplifier. Therefore, before grounding your amp, make sure the gauge of the ground wire matches the gauge of the power wire to assure proper current flow.

So, if the turn on wire and fuses both check out okay, the next thing to look for is continuity on the ground wire. If your amp is not properly grounded, it may fail to turn on or not function properly.

The best and most efficient ground connection is when the wire is attached to a bolt that’s directly connected to the metal chassis, or when it’s touching a point scraped to the metal on the floor pan of the vehicle.

Furthermore, you want to make sure your ground wire is secure. So, use extra screws, a lock washer, a star washer, and any other technique that’ll keep this connection tight, clean, and electrically conducting.

Ground connection should be as near to the amplifier’s location as possible – preferably within eighteen inches of the amp’s location.

P.S: You do not want the ground wire touching paint or any preexisting nut or bolt.

 

4. Amp mounted to a conductive surface

If your amplifier is mounted to a conductive surface, such as when its case is in direct contact with the metal of the vehicle, either directly through the case or through the mounting screws touching metal, there will likely be a problem. Usually this will make your amp go into protect mode though sometimes it may not turn on at all.

So, always make sure your amp is not touching any conductive surface of the vehicle. You could mount your amplifier onto a wooden board or plastic panel and then attach that wherever you want in your car. Another cheap and effective solution is to isolate your amp’s case using rubber grommets around the mounting screws.

5. No voltage in power wire

If everything checks out okay, you need to make sure your amp power wire isn’t loose, corroded, or shorted out somewhere.

The power wire will be much thicker than the remote wire, and it should have battery voltage.

It goes without saying that if your amp is not getting the power it needs, it will not be able  to make the output you want. It’s as simple as that.

For an amp to operate efficiently, its power and ground wires must be large enough to accommodate its demand for electrical current.

Bottom Line

Now that we’ve listed all the things that cause the amplifier to not turn on, stop asking “why wont my amp turn on?”, and do some detective work to track down the faulty part.

Should you find that everything is hooked up correctly, that the amp is mounted to non-conductive surface, that none of the fuses are blown, that the turn on wire has voltage when the receiver is turned on, and that the amplifier has good power and ground, then there’s a good chance you’re dealing with a busted amplifier.

Alex Brown

Hey There, my name is Alex Brown, I'm an LA-based sound engineer with over 10 years experience installing, troubleshooting, and repairing commercial, automotive, and household sound equipment. I've installed highly competitive car audio systems, and everything from navigation systems to full car stereo systems, remote starters, alarms and beyond. I enjoy creating solutions and simplifying everyday needs. I also love helping people get great sounding gear, thereby, saving the world from bad sound one customer at a time.

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