Metra Wiring Harness for Audi and VW: Installation Tips

Quick Answer

The Metra 70-1784 wiring harness lets you connect an aftermarket radio to your Audi (1988-2007) or VW (1980-up) without cutting the factory plugs. Follow these steps to avoid common wiring mistakes.

Installation Steps

1. 1. Disconnect Battery: Disconnect the negative battery terminal to prevent shorts while working on the stereo wiring. Wait 5 minutes after disconnecting to let any airbag capacitors discharge.
2. 2. Remove Factory Radio: Use appropriate removal keys or tools to pull the factory radio from the dash. Unplug the antenna and all connectors. Keep track of any small trim clips or screws; they are easy to lose.
3. 3. Match Wire Colors: Connect the Metra harness wires to your aftermarket radio's wiring harness: yellow to constant 12V, red to switched 12V, black to ground. Match speaker wires by color (left front, right front, etc.). Double-check that constant and switched power are not swapped, or the radio will not retain memory.
4. 4. Crimp or Solder Connections: Use butt connectors or solder and heat shrink for a secure, lasting connection. Avoid twisting wires and taping them. A poor connection here can cause intermittent audio or power loss.
5. 5. Test Before Final Assembly: Reconnect the battery, turn the key to accessory, and test the radio functions: power, sound from all speakers, and any steering wheel controls if applicable. If no sound, check the speaker wire pairing and ensure the radio's fader is set to center.
6. 6. Secure and Reinstall: Tuck all wiring neatly into the dash to avoid rattles or pinched wires. Reinstall the radio and trim pieces. Use zip ties to bundle loose wires away from moving parts like the heater controls.

Product Facts

• Metra 70-1784 Radio Wiring Harness for Audi 88-07 and VW 80-Up: Plugs into car harness at radio; supports 4 speakers. No cutting or splicing of factory wires is needed, making installation faster and preserving resale value.