THe heavy leads going into the module are 12v and ground. YOu can meter the power lead.

The other lead should have 0.0 volts to the frame, and IF it reads 0.0 you can use an OHM meter to verify ground of less than 2 ohms.

Good luck, Woody

BTW the two little leads on the module are digital and need a scope to make sense of.. It could also be the engine thermometer which is on the passenger side of the thermostat, the little black plastic thermisitor module with a two wire connector. WW