Manual - Chapter 6 - Ignition system

2. Precautions to be observed when checking the ignition system

Warning: The very high output of the type of ignition system fitted means that it can be very dangerous or even fatal to touch live components or terminals of any part of the system white it is in operation. Therefore take great care to avoid personal contact with any part of the system white the engine is running, or even when the engine is stopped but the ignition is switched on.

  1. When working on any part of the ignition system, always cut off the power supply either by switching off the ignition key or by disconnecting the battery (negative terminal first). If test procedures require the system to be in operation, take great care to prevent personal contact with any part of the system.
  2. Do not attempt to run the engine with the battery disconnected or with its connections made to the wrong terminals; this will destroy the ignition trigger assembly and may damage the alternator and other electrical components.
  3. Never disconnect or attempt to disconnect the ignition HT leads at the coils or spark plugs while the engine is running; apart from the personal risk described above the coils and control unit would almost certainly be damaged.
  4. Never attempt to test either the trigger assembly or the contra/ unit using equipment which has its own source (eg multimeters, ohmmeters. meggers, or battery and bulb test circuits): the applied voltage may damage one or more of !heir sensitive circuits.
  5. If the resistance of any other part of the system is to be tested, ensure that the power supply is cut off (see above) and that the wires leading to the trigger assembly or control unit are disconnected. This is to prevent the risk not only of personal injury but also of damage either to the tester or to any of the system's components.
  6. Note: Owners of machines used in the US, particularly in California, should note the possible legal implications of attempting to service any part of the ignition system before undertaking such work. Refer to Chapter 5, Section 2 - Precautions to be observed when servicing the fuel system.