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Metra 70-5521

Amplifier Harness for Select 2003-2005 Ford Vehicles

In Stock

List price $29.99

You Save: $22.00 (73.36%)


with warranty

Order within 26 hrs 27 mins to ship 2/2

Arrives by Monday, Feb. 9 to zip 20147

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In Stock

Arrives by Mon, Feb. 9

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Metra Audio Store

Product Features:

  • Factory amplifier integration harness
  • 2 RCA Plugs plug into aftermarket radio's pre-amp outputs
  • One 24-pin power plug and one 8-pin subwoofer plug
  • 1.5K Ohm resistor can be used on the amp-remote wire to eliminate turn-on pop
  • Allows for the installation of an aftermarket radio using the existing factory wiring and connectors
  • No cutting of factory wiring needed
  • Compatible with select 2003-2005 Ford vehicles
  • 1-year Manufacturer's warranty


  • Yellow 12V Constant
  • Red 12V Accessory
  • Black - Ground
  • Orange Dash Light Dimmer/Illumination
  • Green Left Rear Speaker (+)
  • Green with Black Stripe Left Rear Speaker (-)
  • White Left Front Speaker (+)
  • White with Black Stripe Left Front Speaker (-)
  • Purple Right Rear Speaker (+)
  • Purple with Black Stripe Right Rear Speaker (-)
  • Gray Right Front Speaker (+)
  • Gray with Black Stripe Right Front Speaker (-)

Harness Features

Vehicle Sound System
This refers to what kind of sound system the vehicle has. Premium audio systems are generally name brand systems (such as JBL, Bose, Rockford Fosgate, etc) that have been installed inside a vehicle when it leaves the factory. Often they more advanced systems, complex wiring, factory amplifiers, and other features that can make installing aftermarket component difficult.
Standard Sound
Main Harness Function
Different installations on different vehicles require different harnesses. This type is what the harness is considered. Each wiring harness we sell serves a purpose such as installing an aftermarket car stereo, integrating an aftermarket amplifier with your factory car stereo, connecting Bluetooth to your factory car stereo, and more.
Install a Car Stereo & Bypass the Factory OEM Amplifier
Compatible Vehicle Make
Allows you to view only items that are compatible with your vehicle's make. Does not guarantee that it will work with your vehicle year or model.
Compatible Vehicle Make and Model
The model of vehicle that this vehicle specific product is designed for. Please keep in mind that engine variations can affect the compatibility of the products.
Ford Aerostar
Ford Aspire
Ford Bronco
Ford Contour
Ford Crown Victoria
Ford Econoline
Ford Edge
Ford Escape
Ford Escort
Ford Excursion
Ford Expedition
Ford Explorer
Ford F-150
Ford F-250
Ford F-350
Ford F-450
Ford F-550
Ford Flex
Ford Focus
Ford Freestar
Ford Freestyle
Ford Fusion
Ford Mustang
Ford Ranger
Ford Taurus
Ford Thunderbird
Ford Windstar

Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

Summary of Customer Ratings & Reviews

Rating Distribution

5 Star
4 Star
3 Star
2 Star
1 Star

Average Attribution Rating


Monson, MA

Super Easy

January 2, 2015

If you can match colors then you can hook up you radio in under 1 hour. I had to cut the wire covers a bit longer to wrap them befor clamping. All wires were labled also. Simple.

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Taylors, SC

It restored the deep bass to my SUV...

December 31, 2013

Metra harnesses are great quality harnesses. There is a reason that they are the first choice of a vast majority of pro installers. While I'm not a pro, I am quite proficient in the realm of audio installations and I too prefer metra products(although on occasion I have used scosche products as well). This harness includes, besides the interface from aftermarket head unit to the stock vehicle harness, the harness to put the stock sub and amp back into your system when installing an aftermarket head unit. If you already have an aftermarket head unit and just need to integrate the stock sub into your aftermarket system, metra makes a harness for that purpose as well(as I found out after I ordered this harness) and the model number of that harness is 70-5522. Either way, you really can't go wrong and this harness will get the job done and help you to install your aftermarket system with no cutting required to the stock harness. A caveat with the stock sub interface, tho. Be sure to also either install a ready made 12v to 5v inline converter on the remote turn on line, or, if you are aptly capable, install a 7805 regulator should you have one laying around(this was the route I took because I actually did have one laying around). The reason for this is to avoid a loud pop when turning on the amp because of a voltage mismatch between the common remote lead of most systems and the remote lead in on the stock amp.

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Coeur d Alene, ID

Perfect Fit!

December 30, 2013

This product was a great fit and simplified my do-it-yourself installation by making an easy connection/fit between the after market stereo wiring and the stock stereo harness. The only thing that would have made it perfect would be if the harness had the two orange wire dimmer connector that both the stock harness and after market stereo had. The dimmer switch on stereo face doesn't work because of this but the front still lights up and looks great. The team at Sonic included everything i needed.

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Highland Park, IL

Great fit

September 17, 2013

This is the harness needed to interface an aftermarket head unit with the MACH system in my '04 Mustang.
Everything worked great!

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Lathrop Ca

Sonic saved us

February 27, 2012

My sisters fiance has an 04 f150. About a year ago when him and my sister came down from washington i took him to a local audio shop and he got a jvc 7 inch touch screen installed. We later found out that the factory sub no longer worked, went back to the shop and asked them to fix it. They said it would take 45 minutes (my sister didn't want to wait nor did her fiance). This last week they were down again and still no subwoofer. So i came to Sonic and got this harness. Pulled out the deck, hooked it up in about 15 minutes and wahh lahh. The sub worked again, without sonic we would have bought an amp wiring kit, and a new amp.

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Ardsley, NY

Not complete for 2002 Expedition

February 9, 2012

Needed a second harness to activate the subwoofer. After a few back and forth emails to Sonic, they provided it free of charge.

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Browse 1 question and 3 answers
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Why did you choose this?
Sonic Electronix Store
Stereo stores charge about 40.00 for this in UT which is sad. Sonic is the only way to go.
Victor C on Dec 13, 2014
Its exactly what I needed for my install.
LaBarron R on Sep 6, 2014
Perfect match for the mustang harness
Al P on Sep 21, 2014

Product Summary


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Internal SKU


Internal Product ID


Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: Metra 70-5521