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Metra 70-5003 Receiver Wiring Harness

Connect a new car stereo in select 1983-95 Ford, Kia, Mazda, and Mercury vehicles

9 Reviews

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Item # 120705003

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This vehicle-specific wiring harness makes connections between your new car stereo and your car's electrical system.

Metra 70-5003 Receiver Wiring Harness

This vehicle-specific wiring harness makes connections between your new car stereo and your car's electrical system.

First, attach the color-coded wires on your Crutchfield-supplied harness to the wires from your new stereo. If you're not using a soldering iron, we recommend that you purchase some wire connectors to secure the connections. Check out our handy article on three ways to connect the wiring harness here.

Now, once this harness is connected to your new stereo, you'll be able to plug right into your car's factory radio connector. This harness saves installation time since you won't have to cut factory wires individually, and this also enables you to re-install the factory radio if needed. A detailed instruction sheet comes with the harness. Warranty: 60 days.

Please read this important note: This harness may not contain provisions for every wire needed to complete your installation, and it will not accommodate special navigation, video, or factory steering wheel control connections. You will need a special adapter if you want your factory steering wheel audio controls to work with your new stereo.


Note: You'll need to make a ground connection between your new receiver and your car's metal chassis.

  • 12V constant power
  • 12V switched power
  • illumination
  • left front speaker +/-
  • right front speaker +/-
  • left rear speaker +/-
  • right rear speaker +/-

Note: Most vehicles will require additional installation parts — please identify your vehicle if you haven’t done so. You can also call an Advisor for more information.

This harness really helped in the installation. Highly recommended.

Anonymous, Colorado Springs, CO

What's in the Box:

  • 6" Constant power harness
  • 6" Switched power harness
  • 6" Front speaker harness
  • 6" Rear speaker harness
  • Instructions

Metra 70-5003 Receiver Wiring Harness Reviews

Average Customer Review(s):

(9 Reviews)

Metra 70-5003

Anonymous from Colorado Springs, CO on 9/17/2014

1987 Mazda 323
Crutchfield Customer Review (What's this?)

This harness really helped in the installation. Highly recommended.



New radio installation in '87 Mazda B2000

KnoxGuy from Atlanta, GA on 8/26/2014

1987 Mazda B Series
Crutchfield Customer Review (What's this?)

Original radio was not installed according to factory specs so only 2 of 4 adapter harnesses were useful, but the online help (verbal and pdf wiring diagrams) from Crutchfield enabled me to do the rest of the wiring on my own and my radio works just fine.

Pros: Excellent online help; Crutchfield guy took me by the hand and led me to the promised land...

Cons: There are often a lot of surprises when you replace stuff in an old truck. It's not as easy as advertised.

Metra 70-5003 Receiver Wiring Harness

Don Stivers from Brownsburg, IN on 6/3/2014

1987 Mazda RX7
Crutchfield Customer Review (What's this?)

Great instructions, Fast and Easy



Perfect fit

Eric L. from Houston, TX on 4/25/2014

1988 Mazda B Series
Crutchfield Customer Review (What's this?)

The wire harness fit directly into the factory connections, just as described, making the installation of my new head unit a breeze. Thank you, Crutchfield, for providing this item with the stereo unit to make installation simple. This and other reasons is why I continue to be a customer.

Pros: Color coded connectors, pre-stripped wires, easy to understand instructions.

Cons: none

the right harness

rx7 club from cali on 12/8/2013

1988 Mazda RX7
Crutchfield Customer Review (What's this?)

because you need to do it right the first time



1985 3 piece radio

Jacob from Apache Junction, AZ on 4/10/2011

1985 Mazda RX 7, w/three piece stereo system, most matched up but one connector on the stock harness for the back speakers is a white 6 slot connector, and the after market adapter is a blue 4 slot connector. which calls for some problem solving.



Makes life a little easier.

Scott G from Kansas City on 2/5/2011

1993 Mazda B Series
Crutchfield Customer Review (What's this?)

To my suprise they were quality connectors. Foreign made maybe but they still fit together with the factory connectors very well. You will need wire connectors if you do not plan to solder. This type of product is what sets Crutchfield apart from the rest.



Perfect Fit

Jose from Downey, CA on 2/4/2011

1988 Mazda RX7
Crutchfield Customer Review (What's this?)

Bought these for my father's 1988 RX-7 and they were a perfect fit. Thank you Crutchfield.



Perfect fit for 88 Mazda 323 SE

Anonymous from NYC on 6/7/2010

1988 Mazda 323
Crutchfield Customer Review (What's this?)





Hands-on research

Product Research


Crutchfield Wiring Harness: Crutchfield wiring harnesses prevent you from having to cut your vehicle's factory radio plug when replacing your factory radio with an aftermarket head unit. Simply solder or crimp the Crutchfield wiring harness to your aftermarket head unit's harness (solder & crimps not included), plug the aftermarket head unit's plug into the rear chassis of the aftermarket head unit, and plug the Crutchfield wiring harness into your vehicle's factory radio plug.

Note: Installation tools, hardware, & accessories are not included & sold separately. Please see the Accessories tab for recommendations & availability.

Wiring Notes: If the Crutchfield wiring harness is not equipped with a ground wire, you will need to ground the aftermarket head unit's ground wire to the metal chassis of your vehicle. Some vehicle's may require you to bypass the vehicle's factory amplifier (in another location from factory radio) or hardwire certain connections. If your vehicle is equipped with factory steering wheel controls, an additional adapter is required & sold separately.

Wire Code Chart:

(Constant Power Harness)

Wire ColorFunction
Yellow+12 Volt Constant

(Switched Power Harness)

Wire ColorFunction
Red+12 Volt Accessory
BluePower Antenna

(Front Speaker Harness)

Wire ColorFunction
WhiteLeft Front Speaker +
White/BlackLeft Front Speaker -
GrayRight Front Speaker +
Gray/BlackRight Front Speaker -

(Rear Speaker Harness)

Wire ColorFunction
GreenLeft Rear Speaker +
Green/BlackLeft Rear Speaker -
VioletRight Rear Speaker +
Violet/BlackRight Rear Speaker -

Wiring Note: This harness has no ground wire; the new radio must be grounded to the vehicle chassis.

The Crutchfield Car Selector: Please visit theCrutchfield Car Selector for your specific vehicle.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.