Federal Models
- Remove water thermo switches from radiator and intake manifold. Switch in intake manifold (fast idle) has Brown/Red and Yellow/Blue wires attached, switch in radiator (throttle positioner) has Black/Blue and Black wires attached.
- Immerse base of switch in container of cold water. Connect ohm meter across switch terminals. Gradually heat water and observe temperature at which circuit opens. Standard temperature should be between 59-67°F (15-19°C) for radiator switch, 150-157°F (65-69°C) for intake manifold switch.