Thermo Time Switch: Testing and Inspection
THERMOTIME SWITCHTEST
Equipment required: Stop watch, ohmmeter, single pole switch, jump lead for connecting switch to battery and thermotime switch and a thermometer.
NOTE: Check coolant temperature with thermometer and note reading before carrying out procedures detailed below. Check rated value of thermotime switch (stamped on body flat).
Disconnect battery earth lead.
Pull electrical connector from thermotime switch.
A' coolant temperature higher than switch rated value:
Connect ohmmeter between terminal W' and earth. A very high resistance reading (open circuit) should be obtained.
Renew switch if a very low resistance reading (short circuit) is obtained.
B' coolant temperature lower than switch rated value:
Connect ohmmeter between terminal W' and earth. A very low resistance reading (short circuit) should be obtained.
Connect 12V supply via isolating switch to terminal G' of thermotime switch.
Using stop watch, check time delay between making isolating switch and indication on ohmmeter changing from low to high resistance. Delay period must closely approximate to time indicated in table for specific coolant temperature (noted above).
Renew thermotime switch if necessary. Reconnect thermotime switch.
Reconnect battery earth lead.