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Troubleshooting your car amplifier installation

Solutions to some common problems


ccasionally we'll hear from a customer that "Everything's hooked-up correctly, but it's not working right. What can I do?" Sometimes things just don't work like we expect them to right from the start. Here are some of the most common problems that can occur when installing an amplifier — and their solutions.

Factory radios and their security codes

If you're using a factory radio, it may need its anti-theft security code reset. If so, you can usually find the code and resetting procedure in the vehicle's owner's manual, online, or from a car dealership service department (be prepared to prove you own the vehicle).

Using multimeter

Reads good: A multimeter showing the DC voltage powering an amplifier.

Amplifier doesn't power-up

In order to properly and safely troubleshoot a malfunctioning electrical system you'll need to use a multimeter to measure voltages and check continuity. Crutchfield sells the Install Bay 3320 digital multimeter, but if you're in a hurry, you can probably find one at your local hardware or electrical supply store.

  1. Measure the voltage at the amplifier between the ground and positive power terminals. If no voltage is present, go to Step 2. If +12 volts DC is present, skip down to Step 3.
  2. Remove the inline fuse by the battery and check it for continuity. No continuity means the fuse is blown and needs replacing. Good continuity means that a power or ground wire is loose or not connected somewhere along the line.
  3. Measure the voltage at the amplifier between the ground and remote turn-on lead terminals. If it reads +12 volts DC, either the amp's onboard fuses are blown (check continuity and replace if necessary), or there's something wrong with the amplifier and you should return it to your dealer for repair. If you find no voltage here, it means the remote lead is either broken or not connected correctly.
testing wires

Testing: If touching the tip of an RCA conductor connected to the amp's input produces a hum — the wires, amp, and speakers are all good.

Amplifier comes on but no sound comes from the speakers

Finding the problem requires checking every piece of equipment in the audio chain. We'll start at the stereo and work our way to the speakers.

Check the stereo and amp settings

  1. Try turning up the amplifier's gain a little. Make sure all its filters are off or deactivated.
  2. Check your source. Make sure it's really playing music and not idling. If, for example, only some speakers aren't playing but others are, it may be that the receiver's fade or balance control isn't set to the middle. Some receivers have a mute function — you'll want to check on that, too. Make sure the RCA cables are plugged in properly.

Check the stereo's audio outputs

  1. Turn the receiver and amp off. Unplug all the RCA cables from the receiver. Turn the receiver and amp back on.
  2. Now, touch the inner pin of one of the RCA plugs with a finger. If the wiring is good, you will hear a soft hum coming from a speaker. Test all the RCA cables this way.
  3. If all the speakers hum, it means the receiver's not putting out signal and may need to be looked at by a service technician. Or, if you're using a line output converter, it's not hooked up right. If you hear no humming on any channel, turn off the receiver and amp and plug the RCAs back in.

Check the RCA cables

  1. With the receiver and amp off, unplug the RCA cables from the amplifier's input jacks. Get a short RCA cable that you know is good and plug it into the amp's input. Turn the receiver and amp on.
  2. Touch the inner pin of the RCA plug at the free end of the cable, and listen for a hum. Test all the amplifier's channels this way. If every channel hums, it means the RCA cables from the receiver are bad and need to be replaced. If you hear no humming, turn off the system and re-connect the patch cables to the amp inputs.
  3. Another, better, way to perform this test is to plug a portable music player or phone directly to the amp's inputs with a mini-to-RCA adapter from the headphone jack, and play music through the amp.

Check the speaker wiring and speakers

  1. No part of your speaker wiring should touch any part of your vehicle's metal body — that's a short circuit that could damage your amp and speakers. Another place to look for short circuits is at the amplifier's speaker terminals. It's very common to find a strand or two of stray wiring touching another wire, causing none of the speakers to work (the amp has sensed a short and shut down).
  2. Disconnect the speaker wires from the amp. Take a battery, 9 volts or less, and momentarily touch its poles to the positive and negative wires of a speaker. If the wires and speaker are good, you will hear the speaker click. Test all the speakers this way. If all the speakers click, it means the amplifier has a problem and probably needs to go in for servicing.
  3. If the speakers didn't click, you'll need to repeat this battery test at each speaker to determine whether the wire or the speaker itself needs to be repaired or replaced.
Ground wire

Ground: Connected metal-to-metal (no paint) and bolted tightly.

Noise: humming, buzzing, or whining

  • The vast majority of noise problems are caused by bad grounding. If your ground point is free of dirt and paint and making a good connection to your vehicle's frame, try moving the ground to a different spot and see if that clears it up.
  • Actually, any loose wire throughout your car could cause noise, even your battery terminals. Low battery fluid can also be a source of system-wide noise.
  • The case of your amplifier making contact with your vehicle's metal body could cause noise. Any part of the signal system's negative wiring or shielding that touches the car's metal body could cause noise.
  • See How to diagnose and suppress noise for more tips on fixing noise problems.

Capacitors: A cap gets wired to an amp's power input and can provide a burst of energy when the amp's power demands temporarily exceed the electrical system's power supply.

Don't overwhelm your vehicle's electrical system

We have assumed you picked equipment that your car's electrical system can handle. It would be wildly inappropriate, for example, to try to run 5,000 watts RMS worth of amplifiers in a compact car with a small-capacity alternator. Such a system would quickly bog down the car's system and eventually burn out the alternator. Some people, especially competitors, upgrade their alternators to accommodate their high-power systems.

One common symptom of over-powering is the dimming of lights when bass notes hit. If your lights dim just a little during heavy bass passages, you might benefit by installing a capacitor on the bass amp's power cable. Otherwise, check out Headlights dim when the music plays to help solve over-powering issues.

Tech support

Nicole: One of our Technical Support Specialists based at our Norton, Virginia facility.

Crutchfield tech support

Hopefully these tips will help you solve any problem in your system. If you find yourself stymied by the situation, you can always give us a call for help. When you purchase your amplifier system from Crutchfield, tech support is free for the life of your gear. Our amazing tech support team is available seven days a week.

Just click on "Contact Us" at the top of this page for the toll-free number and other methods of contacting us.

  • John

    Posted on 3/10/2023

    My amp button is turned on but the indicator light is off and there is no sound from my speakers

    Commenter image

    Buck Pomerantz from Crutchfield

    on 3/13/2023

    Jon, Without knowing precisely what amp and you're referring to, we can't help you with advice. If you want a question answered about a system, you must identify the gear by brand names and model numbers so we can get the right information to you.
  • natanael from Austin

    Posted on 3/5/2023

    I just installed a rockford amplifier. When i start the ignition everything works good i have a blue lught on ampifier and all speakers works but when i start the engine, my amplifier start blinking blue and red and no speakers dont work.I know red is for short circuit but how this is possible when with only ignition everything works?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 3/6/2023

    Natanael, It sounds like your amplifier has problems when the system's power voltage goes from 12-volts when the engine's not running, to the 13.8-volts or so when the engine is running. That's a problem with the amplifier's internal power supply - and indicates the amp needs repair or replacement.
  • Adrian from Tampa

    Posted on 2/22/2023

    My amp is frying one of my 2 subs even with no input (rca disconnected). I tested the DC chanel output and one that's fine is at 0V and the one frying my sub is at 40v..? What could cause this?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 2/23/2023

    Adrian, That much DC voltage coming out an amplifier's output is very bad - something is wrong with the amplifier. You should fix or replace it.
  • Billi from Frenchville

    Posted on 12/13/2022

    After installing our amp, the front speakers work but the rear only hum? What is the issue with this?

  • George taylor from Toledo ohio

    Posted on 10/16/2022

    I just ordered 4 jl audio rd1500 amps from you guys and my jvc stereo doesn't have enough power to turn the amps on and if I run a wired on and off switch I get alot of popping and engine noise and amps go into protection mode any ideas of what to do ??

    Commenter image

    Buck Pomerantz from Crutchfield

    on 10/17/2022

    George, As you found out, a typical turn-on signal from a receiver doesn't have enough power to turn on more than one or two devices. What you'll need to do is use a relay for the turn-on circuit - using the receiver's turn-on signal to activate a relay switch that connects all the turn-on circuits to a higher-current 12V source, like from the fuse box. Give us a call, so an Advisor can help you get the gear you need.
  • Cameron from Hwange

    Posted on 8/17/2022

    Hey quick question why does my 4 channel digital star amp only turn on when connected to a car battery but doesn't turn on connected indoors with an adapter .the adapters all turned off when connected. How can i make it work indoors with wall plug and laptop adapter

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/18/2022

    Cameron, Without knowing precisely what gear or "adapter" you're referring to, we can't help you with advice. If you want a question answered about a system, you must identify the gear by brand names and model numbers so we can get the right information to you.
  • Tristan Jackson from Downieville

    Posted on 8/4/2022

    So I've been attempting to wire my kicker 10" comp c subwoofer and kicker 400 RMS amp and I'm running into troubles. My remote wire is connected to what appears to be another remote wire running from my alpine aftermarket stereo. Do I tap my remote wire right into the stereo remote wire or somewhere else. First time working with audio so I'm afraid to try mess something up terribly.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/4/2022

    Tristan, The amplifier's remote turn-on lead should connect to the aftermarket receiver's remote turn-on lead, available in its harness, usually as a blue/white wire.
  • Hunter from Clayton

    Posted on 6/29/2022

    I have a kicker kx600.1 amplifier. Early in the morning when I go to work its not putting out much power to my sub but later in the day when I drive home it sounds perfectly fine. Could it just be the chang in temperature? If i listen to in for long periods of time in the morning it slowly starts sounding better

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/1/2022

    Hunter, It does sound like something changes when the system warms up. And to make matters more difficult to troubleshoot, it could be in the receiver or the amp.
  • Jerm from Brooks

    Posted on 3/12/2022

    I got amp hooked up. Power light comes on. As soon as I hook sub up the power light turns red and amp shuts down.. I can hook up a 6x9 and it doesn't kick in to protection mode/red light. Tryed different sub did same thing. Amp is 4000w

    Commenter image

    Buck Pomerantz from Crutchfield

    on 3/13/2022

    Jerm, It sounds like the impedance of the sub you're trying to connect is lower than the amp can handle. But without knowing precisely what amp and sub you're referring to, we can't help you with advice. If you want a question answered about a system, you must identify the gear by brand names and model numbers so we can get the right information to you.
  • Rene from Pasadena

    Posted on 5/6/2021

    I just got the "Rockville Krypton-M3 4000w Max/1000w RMS Mono 1 Ohm Car Amplifier" to go along with my "Rockville W12K9D2 12" 4000w Peak Car Audio Subwoofer Dual 2-Ohm Sub 1000w RMS CEA Rated". My question is, what amp fuse do I use coming from the battery in the power wire? That is all I'm installing. The sub to the amp. Please HELP!

    Commenter image

    Buck Pomerantz from Crutchfield

    on 5/6/2021

    Rene, It looks like that amp can use 4-gauge power and ground wire with a 100 to 120A fuse

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