Jaguar & Triumph

Check engine coolant temperature with a thermometer. Compare coolant temperature with value stamped on thermo-time switch body. If coolant temperature is higher than switch value go on to step 2 ). If temperature is lower than switch value, go on to step 3).
If coolant temperature is higher than switch value, connect an ohmmeter between terminal "W" and ground. A very high resistance (open circuit) should be obtained. If not, replace switch.
If coolant temperature is lower than switch value, connect an ohmmeter between terminal "W" and ground. A very low resistance (closed circuit) should be obtained. Connect battery voltage via an isolating switch to terminal "G" of thermo-time switch. Using a stop watch, check delay time as ohmmeter changes between high and low resistance. Delay period should be as specified in table. If not, replace switch.

Coolant/Delay Time Relationship (Jaguar & Triumph)