The required resistance values differ between thermo-time switch models.
The resistance should reach 0 Ohms (continuity) with engine temperature below:
| Bosch part no. | Temperature (F) | Temperature (C) |
|---|---|---|
| 0 280 130 219 | 50 | 10 |
| 0 280 130 221 | 56 | 13 |
| 0 280 130 214 | 86 | 30 |
The resistance should rise to infinity with engine temperature above: Infinite resistance with engine temperature above:
| Bosch part no. | Temperature (F) | Temperature (C) |
|---|---|---|
| 0 280 130 219 | 68 | 20 |
| 0 280 130 221 | 74 | 23 |
| 0 280 130 214 | 104 | 40 |
If resistance value lies outside of specification, thermo-time switch is defective.