2. Electrical system: general information and preliminary checks

  1. In the event of an electrical system fault, always check the physical condition of the wiring and connectors before attempting any of the test procedure described here and in subsequent Sections. Look for chafed, trapped or broken electrical leads and repair or renew these as necessary. Leads which have broken internally are not easily spotted, but may be checked using a multimeter or a simple battery and bulb circuit as a continuity tester. This arrangement is shown in the accompanying illustration. The various multi-pin connectors are generally trouble-free but may corrode if exposed to water. Clean them carefully, scraping off any surface deposits, and pack with silicone grease during assembly to avoid recurrent problems. The same technique can be applied to the handlebar switches.
  2. A sound, fully charged battery is essential to the normal operation of the system. There is no point in attempting to locate a fault if the battery is partly discharged or worn out. Check battery condition and recharge or renew the battery before proceeding further.
  3. Many of the test procedures described in this Chapter require that voltages or resistances be checked. This necessitates the use of some form of test equipment such as a simple and inexpensive multimeter of the type sold by electronics or motor accessory shops.
  4. If you doubt your ability to check the electrical system entrust the work to an authorised BMW dealer. In any event have your findings double checked before consigning expensive components to the scrap bin.
  5. Note that on these machines many puzzling electrical faults can be caused by poor earths between the engine/transmission unit and the frame, particularly at the bellhousing/frame mounting bracket and the main frame earth. Clean the mating surfaces back to bare metal at these points, scraping away the frame paint, where necessary, and apply a thin coat of silicone grease or similar to prevent corrosion before bolting up the components again.

Fig 10.1