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How to tap into a car fuse box

Using a fuse tap for accessory or amp turn-on power

If you're installing a car amplifier that needs a turn-on signal or a low-power device that requires 12 volts, you can get the voltage you need by tapping into your vehicle's fuse box with a fuse tap. This handy little piece of hardware adds a new fused circuit to the factory electrical system safely and neatly. In this article, we present step-by-step instructions on how to do it.

Accele FT-ATC

What's a fuse tap do?

A fuse tap allows you to get 12 volts from your vehicle's fuse box for a low-power device, like an active signal processor, an amplifier turn-on circuit, a radar detector, or a backup camera. Because of the thin size of a fuse tap's power wire, you should only use one to power a device that will draw no more than 5 amps of current or put out no more than about 52 total watts of power.

You should not use a fuse tap to supply power for an amplifier — that would be dangerous to your vehicle's electrical wiring. An amplifier requires a thick power cable to be run from the amp directly to the battery.

How to install a fuse tap

The rest of this article will walk you through the process of installing a fuse tap. The first step is to find an appropriate circuit to tap into and make sure you have the right kind of fuse. Then install it, test it out, and button it up. Let's go.

2016 Chevy Cruze center console fuse box

Find the best fuse to tap

Step 1: Locate an interior fuse box that is easily accessible and will provide a direct and short path for the power wire to be run to the accessory.  Do not use a fuse box in the engine compartment, because the fuse tap won't provide a water- or heat-proof connection necessary for under-the-hood electrical wiring.

fuse diagram on cover located on lower dash on driver's side

Step 2: Take the cover off the fuse box. There will be a diagram or chart of the fuses with their locations and functions labeled. Identify an appropriate fuse and circuit to tap into that will power on and off with the car.

  • Good choices include the radio, an interior light, a lighter-type charger port, etc
  • Avoid using circuits for the starter, airbags, sensors, unknown "alphabet soup" labels, etc
  • You can use an empty fuse socket, if it powers on and off with the car. Test with a meter, if possible.

Step 3: Identify the type of fuse, so you can get the right size fuse tap and accessory fuse. The owner's manual should identify the type of fuse used in your vehicle

How to install the fuse tap

Step 4: Switch off the car. Remove and set aside the factory fuse.

Step 5: [Skip this step if you don't have a meter.] Turn on the car. If you have a DC volt meter, test and identify the hot (+12V) and load (0V with fuse pulled) sides of the fuse socket, and confirm that the hot voltage switches on and off with the car.

Step 6: Connect (crimp) the fuse tap wire to your new accessory device's power wire.

Step 7: With the car switched off, plug the fuse tap into the removed fuse's socket, with common side contact to the hot socket and the wire side contact to the load socket.

Step 8: Plug the appropriate fuse for the new device into the tap's accessory fuse slot.

  • The accessory fuse will be wired in parallel with the factory fuse, so the factory circuit will be fused at the sum of their ratings, which could be dangerous to the wiring if the accessory fuse is too large
  • For safety, use an accessory fuse that's rated much smaller than the factory fuse
  • Use an accessory fuse rated for 5A or less

Test, troubleshoot, then button it up

Step 9: Switch on the car and new device.

  • If there's no power or turn-on for the accessory: switch the car off, reverse the fuse tap in its socket, then turn the car back on
  • If the accessory powers on: okay

Step 10: Turn off the car, and then plug the factory fuse in the proper slot of the fuse tap, if it was removed in Step 4. (Adding a fuse to a circuit that didn't originally have one could damage factory wiring.)

Step 11: Secure the new power wire in position. Close the fuse box cover.  You may have to modify the cover to allow the fuse tap and new wire to sit neatly inside without being pinched or interfered with.

Tap into the fuse box on Jeep Wrangler in engine compartment.

Make sure you have everything

If you don't already have all the wiring hardware necessary to conveniently power-up your new device from a fuse box, give us a call or chat with us online to get everything you'll need. Crutchfield's the best place to get car audio wiring hardware like fuse taps, fuses, and hookup wire, because of the added benefits of receiving free lifetime technical support with your purchases.

  • Paul

    Posted on 2/25/2024

    Hey there Crutchfield family. Love you guys. I have a weird problem I believe is tied to the REM/fuse tap. Installed a JBL BassPro powered sub in my 2023 Honda HR-V that rocks. My only problem is that the sub "thumps" when I change the gear from drive/reverse/neutral back to PARK. It only happens when switching to PARK. I've tried using two open slots and it seems to happen in both. Sanded down the grounded connector to exposed in the wheel well. Should I try to tap some different fuse locations or do you think this is a different problem. Any help would be much appreciated

    Commenter image

    Buck Pomerantz from Crutchfield

    on 2/26/2024

    Paul, Try disconnecting the sub entirely - power, ground, and input signals - and see if the thump noise still happens when you move the shifter to Park. Is so, it's your vehicle's transmission, not the sub, making bad noises. If not, try it again with just the power and ground reconnected. If the thump returns, the power wiring has some issues. Could be a loose connection at the battery, fuse, or any other point in the circuit. If there's still no thump, then try it again with the input wiring reconnected. Then, if the thump returns, you'll at least know which wiring you'll need to tighten, fix, reroute, or isolate.
  • Murphy from Phoenix

    Posted on 12/1/2023

    2024 Camry. Subwoofer pops when turning car off. Running Fosgate sub and amp. Using LC2i pro as well. Equipment is all brand new. I'm assuming I need to tap into my fuses but unsure which to use. Radio fuse gives constant power. Any other fuse suggestions or should I just start going one by one?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 12/4/2023

    Murphy, Most new vehicles have complex factory audio systems that include noise control modules as well as accessory power management systems that play havoc with aftermarket systems. These vehicles require interface devices that will preserve all factory functions and allow your aftermarket gear to operate properly. Give us a call, and an Advisor will help you find the interface module and wiring harness that'll work for you and your vehicle.
  • MGM from Parrott

    Posted on 11/16/2023

    Good and accurate reading - - Once a fuse tap is installed the cover won't go back on the fuse box (2008 Grand Marquis)

  • William from Portage

    Posted on 8/18/2023

    98 mustang GT popping noise from sub when turning off ignition. If I remove the remote wire from the head unit and hook to a fuse under the dash will this cure my issue?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/21/2023

    William, It's difficult to impossible to know if your amplifier is causing this without knowing the brand and model amp and how it's wired. Maybe you need a tined relay, in order for the pop to disappear.
  • Joseph

    Posted on 8/16/2023

    So if I add a fuse tap to the radio/power off cig lighter (it's an 86 truck) that has no power with ignition off then what ever i connect to the fuse tap will also have no power when the ignition is off?

    Commenter image

    Buck Pomerantz from Crutchfield

    on 8/17/2023

    Joseph, Yes - anything you connect to a switched circuit will turn on and off with that circuit. It will also already have a fuse in it (the car's).
  • Steven from Newport News

    Posted on 7/9/2023

    I'm looking for a solution and hope you could offer an answer. I have a 2004 Tacoma and like most late models the cigarette lighter socket and other auxiliary power sockets do not energize until the ignition is turned on. I would like to mount a solar panel battery trickle charger on the dash and plug into the cigarette lighter or other auxiliary power socket to charge the battery. This is important to me since my truck is left on the streets for weeks at at time. Is there a way to keep the power sockets on while the ignition off (since by doing so will allow charging) by doing some modifications in the fuse box? I think a lot of people would be interested if there's a simple solution allowing them to charge electronics in their car while the ignition is off. Thanks.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 7/10/2023

    Steven, You should not use your vehicle's auxiliary power socket to charge the battery. That circuit passes through the vehicle's fuse box and ignition switch. You do not want a charger on that part of the vehicle's electrical system. Connect your battery charger directly to the battery, like it was designed to do.
  • Jim

    Posted on 6/10/2023

    The fuses in my truck are low-profile, and a low-profile fuse tap is a tiny bit too fat to push all the way down into the socket. The mini-ATC plugs in just fine, but if I use it, I can't snap the cover onto my fuse panel. I don't want to leave the cover off of the fuse panel and risk having electrical problems due to dirt, dust, etc. If I could get a low-profile fuse that would allow me to insert a wire into one side (the draw side), that would solve my problem; but so far, I can't even find any discussion on this topic, let alone a fuse of that nature.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 6/13/2023

    Jim, This is one of many challenges that often come up in car audio installations. Rather than modifying your vehicle's fuse box, which may compromise safety, you might consider running a dedicated fused wire directly to the battery in order to create your new voltage source.
  • Marc from Allentown

    Posted on 2/16/2023

    Can I use one of these to add a secondary car horn to my car. My real question is if I put the tap into the current horn will that drain the battery? Looking for tap location in fuse box. Thank you.

    Commenter image

    Buck Pomerantz from Crutchfield

    on 2/17/2023

    Marc, Installing a second fused device to an existing fused circuit may draw too much power and blow a fuse when both devices are energized at the same time, but it shouldn't drain the battery. It may be better to use a spare active fused circuit for your second horn to get power from.
  • Jamie Tolassi from Falmouth

    Posted on 1/22/2023

    Hi, I have a 2013 Ford Fiesta se that has no accessory wire and I'm trying to install an aftermarket radio. I need to tap into a fuse but am a little confused. I install the factory fuse in one slot of tap, where does the other fuse come from? Do I use the one from the back of the radio? Thanks

  • Clint moore from San Antonio

    Posted on 1/21/2023

    Saw this product in a YouTube video for hooking up Led fog lights with DRLs, does the hook up you show work the same way with the lights and is there anything special I should know about, what size fuse should be used for the fog/drl lights

    Commenter image

    Buck Pomerantz from Crutchfield

    on 1/23/2023

    Clint, This article is about adding a low-current accessory power source. Higher current devices like lighting will require a larger fuse - the value of which depends on the lighting system used and its current draw specifications.

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