Manual - Chapter 4 - Cooling

11. Cooling system electrical components: removal and refitting

  1. Since no test data is available, none of the electrical components can be checked except in the most general terms. See Chapter 10 - Electrical
  2. Coolant temperature sensor

  3. This unit is screwed into the right-hand side of the coolant pipe stub; it is therefore necessary to drain the coolant (Section 2 - draining) and to remove the radiator (Section 5 - Radiator: removal, cleaning and examination) to gain access to it. Unplug its connector and unscrew the unit to remove it; apply a smear of sealant to its threads and renew its sealing washer on refitting.
  4. The unit is connected directly to the fuel injection control unit and to the temperature sensing switch unit which controls the fan motor and the coolant overheat warning lamp. If it is thought to be faulty it can be tested only by substitution.
  5. Temperature sensing switch unit

  6. This unit controls the coolant overheat warning lamp and the fan motor. It is mounted by one or two screws in the electrical components box underneath the rear of the fuel tank. If thought to be faulty it can be tested only by substitution
  7. Coolant overheat warning lamp

  8. This is merely a bulb which is renewed if faulty as described in Chapter 10 - Electrical. However, if it should light when the engine is still cold, the fault is most probably due to a poor earth connection between the engine and frame. Clean the bellhousing/frame mounting point as described in Chapter 1, Section 36 - Refitting the engine unit to the frame, also the frame earth point behind the steering head. Both must be cleaned back until metal-to-metal contact is restored to ensure a good earth; apply a thin coat of silicone grease to prevent corrosion and tighten the mounting bolts securely.

11.2 Coolant temperature sensor is mounted in coolant pipe stub

11.4 Temperature-sensing switch unit is mounted in electrical components box