Cooling system sensors

1 A coolant temperature sender switch is located in the cylinder head (above No. 1 spark plug) on 903 cc engines and adjacent to No. 2 spark plug on 1116 cc and 1301 cc engines. 2 The switch operates the coolant temperature gauge and an excessive temperature warning lamp. 3 On some models, a level sensor is screwed into the side of the expansion tank. This sensor consists of a pair of reed switches within a capsule which are kept closed by the strong magnetic flux generated by the hydrostatic force inspired by the action of the coolant against the float. 4 If the coolant level drops then the magnetic flux is weakened and the switches open.

5 In the event of a fault developing, before assuming that the cause is the sensor, check all connecting wiring.