Sponsored by HUMAN Speakers European Headlights
in the 90 Quattro

problem & solution - process - parts list - city lights - graphics
the lights - the schematic - the harness - installation - results

    The schematic for my wiring harness:

Wiring notes:
  • The grounds are arranged as follows:
    • Each headlamp assembly is grounded by a 15" 10 gauge wire to a nearby bolt.
    • The relays (and bumper lights) are grounded to a bolt near the control unit.
    • The repeater light harness has its own ground ring terminal.
    • The fog lights share a ground at a bolt in the middle of the center support
  • The main power feed is an 8 gauge wire attached to the alternator output.
  • I used 20 A circuit breakers (from Audi power windows). 25 and 30 A are also available.
  • The relays are all Bosch 40 A units scavenged from parts cars.
  • All splices are soldered and sealed with shrink tubing.
  • Wherever possible, I used the appropriate color coded wire... from about ten Audis...
  • The six input signals are taken from the remains of the stock wiring, via a six pin connector. The colors shown above resulted from the use of random available pieces, and they correspond to the car's wiring thusly:
      BrownGrey/RedParking lights
      Red/BlueWhiteHigh beams
      Red/YellowYellowLow beams
      Yellow/BlackBlack/GreenRight signal
      Red/BlackBlack/WhiteLeft signal