THERMO Time Switch
- Using a thermometer, check engine coolant temperature. Compare coolant temperature with value stamped on thermo time switch body. Connect an ohmmeter between terminal "W" on switch and ground.
- If coolant temperature is higher than switch value, a very high resistance denoting an open circuit should be obtained. If coolant temperature is lower than switch value, a very low resistance denoting a closed circuit should be obtained. If switch does not respond as outlined, replace thermo time switch.
- If switch passes resistance test, allow coolant temperature to cool below stamped value on switch. With ohmmeter connected, connect battery power via an isolating switch to terminal "G". Using a stop watch, check delay time as ohmmeter changes between high and low resistance. Delay period should be as shown in Coolant/Delay Time Relationship chart. If not, replace thermo time switch.
Coolant/Delay Time Relationship
| Temperature (Coolant) | Delay (Seconds) |
|---|---|
| -4°F (-20°C) | 8 |
| 32°F (0°C) | 4.5 |
| 50°F (10°C) | 3.5 |
| 95°F (35°C) | 0 |