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Resistor wire for GEN lamp circuit modification on Bosch alternator systems. If the GEN light burns out or the original instrument cluster is removed, this modification will allow the Bosch alternator to still produce electricity.


  • Vehicle Manufacturer: BMW
  • Application: Airhead
  • Model Years: ALL
  • Vehicle Mfg. Part #: N/A
  • Resistance: ~330ohms
  • Length: 24 inches


Installation Guidelines:
This resistor modification will act as the lamp if the lamp/bulb or entire instrument cluster is removed. Install the jumper cable included with the GREEN end connected to a switched B+ such as the coil B+ terminal. Attach the BLUE end to the D+ BLUE wire as part of the front engine harness. There are a number of point this can be done. Depending on your specific configuration, choose one of the following.
1. At the voltage regulator plug BLUE wire with the attached BLACK Posi Tap.
2. Connect the BLUE wire of the resistor wire to the terminal on the front engine harness BLUE wire white plug. This terminal would have a blue wire from the main chassis harness connected here (which used to terminate at the instrument cluster generator light).
3. To the spare D+ terminal on a stock diode board. Original / stock style diode boards have two D+ terminals, and only one is used on BMW motorcycles. The spare terminal on the diode board is part of the same rotor energizing circuit. Regardless of which of the three you choose, you must disconnect the original blue wire connection to the chassis harness (typically a white plug under the tank) which goes to the generator light, for your charging system to function.

Cable ties are included to secure the wire and take up any slack in its installation. This installation must be handled with care and precision with no bare wires or threat of fouling due to vibration