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Metra 70-1857 Bypass Harness

Allows you to connect a new car stereo in select Bose®-equipped 1990-96 GM vehicles

Item #: 120701857

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Metra's 70-1857 bypass harness lets you replace the factory radio in select Bose®-equipped 1990-96 GM vehicles using the existing wiring and connectors. This harness bypasses the remote tuner in certain vehicles, while retaining use of the Bose® audio system. Warranty: 1 year.

Please enter your vehicle information or call an Advisor at 1-888-955-6000 to find out if this model is compatible with your vehicle.

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.

Metra 70-1857 Bypass Harness Reviews

Average Customer Review:

23 Reviews

Easy to install

Written by: Sam from Maryland on December 12, 2015

1996 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

Was very easy to install and had plenty of length to reach where I needed it to.

Pros: Long wires Well labeled Easy to install

Cons: None

Does the job

Written by: Gusvette from Oregon on October 9, 2015

1996 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

Great interface, but 6' of extra cable

Pros: Works perfectly

Cons: I had about 6' of extra cable when finished. A cable designed for specific autos would be great.

Must have for replacing Bose

Written by: jm2088 from Alabama on September 25, 2015

1994 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

This was a huge help with replacing the Factory Bose unit in my 94 corvette. It has all of the connections you need. There are no instructions but basically you need to check out the instructions at ZIP corvette. You will need to run the wires along the passenger side of the car. (Zip recommends removing the seat but I didn't need to do that. It's a big job but well worth it.

Pros: Good cost. Everything you need for the job

Cons: None - This is a weekend project but that has nothing to do with this harness.


Written by: pumasixtynine from grand terrace, ca. on March 31, 2015

Crutchfield Customer Review (What's this?)

Awesome, works as described! fast shipping!

Pros: Perfect fitment!

Cons: None!


Written by: RANDY from Texas on January 18, 2015

1994 Chevrolet Corvette
Crutchfield Customer Review (What's this?)



Cons: N/A

1993 Caddy Radio project

Written by: dtb from Edgewater,Fl on September 14, 2014

Crutchfield Customer Review (What's this?)

Ordered the wrong wiring harness even after talking to a consultant that advised me of a possible error I had made but I didn't listen to him. Great products/Great people/Great Company!! Have the right part now after swapping out. I have dealt with Crutchfield before on other products & vehicles and cannot put into words how impressed I am with all aspects of this Company. You will always have my business and I am recommending your Company to all my friends and family . Your Professionalism, Product support, Outstanding Staff are what is all about. Wish the rest of America would figure that out! Great job!!

Pros: Professional, Knowledgeable Product & Customer Support Outstanding ,

Cons: None!

Metra 70-1857 Bypass Harness

Written by: Andy from Pelham nh on September 13, 2014

1992 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

A well made harness but it was only a little helpful and I only used some of it . I believe this was because of my vehicle type which is a 1992 corvette with a Bose system but on another Chevrolet product I think it would be fine

Pros: It had some parts necessary to connect to existing connectors

Cons: I still had to buy wire and wire up all the speakers

Defintely easier install

Written by: Tom from Evansville, IN on July 27, 2014

Crutchfield Customer Review (What's this?)

Good Idea

Pros: All wires were correct. Nice to be able to plug into the harness without running all new wires and I was able to use the original BOSE Amps and speakers.

Cons: The wiring only needed to be about 5 to 6 feet long and was probably 20 feet long. The RCA and Antenna wires are already finished with plugs on both ends so I didnt' want to cut those. Just wound them up, zip tied them and put them under the dash.

Not quite the way I thought it would work

Written by: OD from Baltimore, MD on May 30, 2014

1995 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

While supposedly this was meant for my '95 corvette, and the instructions were fine, it somehow didn't quite fit the way I envisioned it. The product itself was great, and very long which turned out to be useful.

Pros: good product, worth the money

Cons: didn't fit the way I thought it would

Metra 70-1857 Bypass Harness

Written by: dude from Farley, IA on May 19, 2014

Crutchfield Customer Review (What's this?)

I just want to say thank you so much to the crutchfield team of techs that helped me install my stereo I had to call a couple of times for help . My stereo sounds excellent once again thank you . I have since recommend crutchfield to my friends .

Pros: Great selection of product at a great price .

Cons: Can't say anything bad .

Metra 70-1857 Bypass Harness

Written by: Steve from Bridgeview Il. on April 7, 2014

1990 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

This adapter is the perfect answer to the problem of connecting to a bose amplified speaker system. It would be a bargain at twice the price.

Pros: There really is no better way to connect an aftermarket head unit to a factory bose system. super easy plug and play install.

Cons: The cables can be much to long for some applications and become difficult to package.

Did everything as advertised

Written by: gliot1 from Lake in the Hills, IL on March 17, 2014

1996 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

The cable itself was awesome. The directions only included a wiring diagram; no instructions. In the case of a Corvette Bose system, this cable is intended to connect to the hidden pre-amp behind the seat. In my case I believed it connected into the wire harness behind the head unit, but the connectors would not match up. Nothing in the included paperwork indicated this. I will say, though that one call to the Crutchfield Help desk solved the issue in under 2 min. The tech knew immediately the specifics of the '96 Corvette and pointed out where the cable connected. It was very refreshing to have someone pick up the phone immediately and speak clearly, in proper English as well! High five to Crutchfiled!

Pros: This cable mates to the stock Bose system with perfection. I would have given 5 stars for better instructions

Cons: The instructions tell you little and are simply a wiring diagram.

Metra 70-1857 Bypass Harness

Written by: Anonymous from Clayton, CA on October 21, 2013

Crutchfield Customer Review (What's this?)

Harness is 17 feet long which may be required for some applications. 6 feet length would have worked for my application. The power leads can be cut down but the amplifier leads would be more difficult and you would require a shorter antenna lead.




Written by: Jackie from Wellesley, MA on May 24, 2013

1991 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

Ordered this for my HD pioneer, for my 91 Corvette base model with Bose system. This is allowing the faders to work. It simplified everything!!! Not confusing at all either. Troy was very helpful in finding what i needed. Thanks!!!!

Pros: Simple, organized, color-coded, problem solving


Great adapter!

Written by: Vette Guy from Alexandria, VA on April 21, 2013

1991 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

Perfect adapter and quality connections. Be prepared to have a lot of wire. It weighs a few pounds, and is enough wire to span the length of a SUV!

Pros: Perfect fit

Cons: A lot of wire that you'll have to hide as there is no cutting the RCA cables. I estimate 10' of wire.

Must havve

Written by: csthews from TX on April 19, 2013

1995 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

Without this, the installation would have been a nightmare

Pros: Easy install. Great instructions and phone support

Cons: None

Works!!!!! Not and really easy

Written by: Fast & Loud from Phila. Pa. on April 8, 2013

1992 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

Very good Quilty wires and plug.........

Pros: Lots of wire!!!

Cons: Way to long of an antena wire does not need to be 10 foot long maybe 6 foot at the most!!! the problem is you have to make the dash fit together but it did you have to just have to think outside the box and you'll find a spot to hide the wires........

Metra 70-1857 Bypass Harness

Written by: doug16 from ohio on November 21, 2012

didnt come with line filters

Pros: long wires

Cons: no line filters

Every thing I needed

Written by: Maurice D from Cedar Rapids IA on July 16, 2012

1994 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

After a couple discussions with the tech at Crutchfield, the harness was pretty easy to figure out, worked great.

Pros: All conections to were well researched by Crutchfield.

Cons: none

Works great

Written by: noelia_10 from Manville N.J. on June 13, 2012

1992 Chevrolet Corvette
Crutchfield Customer Review (What's this?)

Installed on 1992 corvette with Bose system worked excellent. Attached aftermarket head unit to bose speakers. Only down fall to much wire for my application should be more tailored to vehicle.

Pros: Worked as intended

Cons: To much wire for application

Wire harness

Written by: Ted from Piqua Ohio on May 22, 2012

Had no instructions

Pros: None

Cons: Need info to hook up

Crutchfield response on May 30, 2012 Thanks for your comment. This adapter works in many different vehicles, and we do offer complete instructions for most of them. If you need information that doesn't come with your product, our tech support specialists can provide it over the phone.


Written by: tommy c from new york on May 1, 2012

Crutchfield Customer Review (What's this?)

A helpful piece for and easier install. I used it in my 92 cadillac eldorado with bose!

Pros: Sounds and works well!

Cons: when turning the radio on makes a thump sound. but other than that pretty clear!


Written by: aaron from pontiac il on February 25, 2012

1994 Cadillac Eldorado
Crutchfield Customer Review (What's this?)

helpful easy to install but there is some unwanted noise the most difficult stereo ive done yet 1994 cadillac eldorado with bose stereo

Pros: stereo works now

Cons: lousy sound

Hands-on research

What's in the box?

Download owner's manual

  • Receiver wiring harness (includes antenna cable)

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:

Wire Color Function
Black (thick cable) Antenna Cable
Red +12 Volt Accessory
Yellow +12 Volt Constant
Black (3) Ground
Blue Power Antenna
White RCA Left Front Channel
Gray RCA Right Front Channel
Green RCA Left Rear Channel
Violet RCA Right Rear Channel


  • There are three ground wires in the harness; all three should be connected to the new receiver's ground lead.
  • The male RCA plugs on the harness are plugged into the front and rear line-level outputs on the new receiver.

The Crutchfield Car Selector: Please visit the Crutchfield 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.

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New head unit for 1991 Corvette ZR-1 [ PETER  Jan 26, 2016 ]

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