Product Overview
The Metra 70-1787 is a radio wiring harness designed to facilitate the installation of an aftermarket radio in select Volkswagen and Audi vehicles equipped with a Bose amplifier system, manufactured between 1993 and 2007. This harness provides a tuner bypass and integrates with the existing Bose amplifier, ensuring proper audio functionality. It includes an antenna extension and is 17 feet long for flexible routing.
Important Note: The vehicle's audio system must be amplified before using this product.
Image: Close-up view of the Metra 70-1787 radio wiring harness, showing the black and red multi-pin connectors. These connectors are designed to interface with the vehicle's factory wiring and the aftermarket head unit.
Image: The Metra 70-1787 radio wiring harness displayed in its clear retail packaging, labeled "VW Audi Amplified Harness 70-1787". The packaging highlights features like "Radio Wiring Harness," "Quick & Easy Installation," and "No Cutting Required."
Installation Instructions
This harness is designed for a no-cut installation, preserving your vehicle's factory wiring. Professional installation is recommended.
Before You Begin
- Ensure your vehicle is compatible with the Metra 70-1787 harness (VW/Audi with Bose amplifier, 1993-2007).
- Disconnect the vehicle's battery to prevent electrical shorts.
- Gather necessary tools: wire strippers/crimpers, electrical tape, zip ties.
Wiring Connections
Match the wires from the aftermarket radio to the corresponding wires on the Metra 70-1787 harness. Refer to your aftermarket radio's manual for its specific wiring diagram. Common wire color functions are typically standardized, but always verify.
- Connect the power wires (typically yellow for constant 12V, red for accessory 12V, and black for ground).
- Connect the speaker wires. The Metra 70-1787 includes RCA connectors for amplifier integration. Connect these to the pre-amp outputs of your aftermarket radio.
- Connect the amplifier turn-on wire (usually blue/white) from the aftermarket radio to the amplifier turn-on wire on the harness.
- Connect the antenna extension cable from the harness to your aftermarket radio's antenna input.
- Secure all connections with crimp caps or solder and insulate with electrical tape or heat shrink tubing.
Final Steps
- Carefully route the harness and excess wiring to avoid pinching or interference.
- Connect the Metra harness to the vehicle's factory wiring harness.
- Reconnect the vehicle's battery.
- Test the aftermarket radio's functionality, including all speakers, radio reception, and other features.
- Reassemble the dashboard components.
Operating Instructions
The Metra 70-1787 wiring harness is a passive component that facilitates the connection between your aftermarket radio and the vehicle's existing audio system. Once installed correctly, its operation is transparent. All audio functions and controls will be managed directly through your aftermarket head unit. Refer to your aftermarket radio's user manual for specific operating instructions.
Maintenance
The Metra 70-1787 wiring harness requires no regular maintenance. Ensure all connections remain secure and free from moisture or physical damage. If you experience any audio issues, inspect the connections for corrosion or looseness.
Troubleshooting
No Audio Output
- Verify that the vehicle's Bose amplifier is receiving power and is functioning correctly.
- Check the amplifier turn-on wire connection (blue/white wire) from the aftermarket radio to the harness. Ensure it is properly connected and receiving a signal from the radio.
- Confirm that the RCA connectors from the harness are securely plugged into the correct pre-amp outputs on the aftermarket radio.
- Ensure the aftermarket radio's volume is turned up and not muted.
Distorted or Poor Sound Quality
- Check all speaker wire connections for proper polarity and secure contact.
- Ensure the gain settings on the aftermarket radio's pre-amp outputs are not set too high, which can cause distortion.
- Verify that the vehicle's factory amplifier is not overdriven or malfunctioning.
No Radio Reception
- Confirm the antenna extension cable is securely connected at both ends (harness and aftermarket radio).
- Ensure the aftermarket radio's antenna input is functional.
- Some Audi/VW vehicles have a powered antenna. Ensure the blue wire (power antenna/remote turn-on) from the aftermarket radio is connected to the corresponding wire on the harness to power the antenna amplifier, if applicable.
Specifications
| Feature | Detail |
|---|---|
| Model Number | 70-1787 |
| Brand | Metra |
| Compatibility | VW/Audi vehicles with Bose amplifier (1993-2007) |
| Function | Tuner bypass and Bose amplifier integration |
| Harness Length | 17 feet |
| Included Components | Wire Harness, Antenna Extension |
| Material | Acrylonitrile Butadiene Styrene |
| Item Dimensions (L x W x H) | 7.5 x 4.5 x 2 inches |
| Item Weight | 0.05 Pounds |
Warranty and Support
Warranty Information
The Metra 70-1787 Radio Wiring Harness comes with a 1-year limited warranty. This warranty covers defects in materials and workmanship under normal use. Please retain your proof of purchase for warranty claims.
Customer Support
For technical assistance, installation questions, or warranty inquiries, please contact Metra Electronics customer support.
Phone: 1-800-253-TECH (8324)
Website: www.metraonline.com
