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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. Our amazing tech support team is available seven days a week.

If you purchased your amplifier system from Crutchfield, that service is free for the life of your gear. If you purchased elsewhere, you can still get access to our tech support for a fee — 90 days of support for $29.99.

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

  • 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
  • Bryan Ailey from Ponca City

    Posted on 4/1/2021

    So we just set up a amp in my car and with the car off we get the 12 bolts on the remote wire. However when we turn the car on it goes down to 2 and the amp won't turn on

    Commenter image

    Buck Pomerantz from Crutchfield

    on 4/2/2021

    Bryan, The remote wire is hooked up to the wrong powered connection. Find one, in the fuse box or receiver remote out, that reads zero volts when the car's off and 12 volts DC when the car's on.
  • Joey

    Posted on 11/12/2020

    So my system was hooked up and it played for imma say 2 days then cut out. It was a factory radio some I'm using a converter I've changed converter and checked all wires and still nothing the amp will come on just no sound is being played.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 11/13/2020

    Joey, Start by performing the troubleshooting steps outlined in the "Amplifier comes on but no sound comes from the speakers" section of this article. You'll eventually find the problem. Or, you could take your car to a car audio installer for repair.
  • Jim stratford from Farmingville

    Posted on 7/1/2020

    Thank you for the troubleshooting guide. Clear and concise instructions should resolve most problems.