About the Metra 70-1857 Bypass Harness
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.
What's in the box:
Metra 70-1857 Bypass Harness owner's manual
- Receiver wiring harness (includes antenna cable)
Reviews (70)
Customer reviews for Metra 70-1857 Bypass Harness
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More details on the Metra 70-1857 Bypass Harness
Product Research
Features
Metra Wiring Harness: Metra 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 Metra 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 Metra 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 Metra 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 vehicles 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 | Amp Remote |
| White RCA | Left Front Channel |
| Gray RCA | Right Front Channel |
| Green RCA | Left Rear Channel |
| Violet RCA | Right Rear Channel |
Notes:
- 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.
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Customer Q&A
3 questions already asked
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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!!!!
Jackie from Wellesley, MA