RAM 2500 Truck 4WD V10-8.0L VIN W (1997)
Temperature Gauge: Description and Operation
SYSTEM OPERATION
The coolant temperature gauge gives an indication of the engine coolant temperature. The coolant temperature sending unit is a thermistor-type
sensor that changes its internal electrical resistance with changes in the engine coolant temperature. The sending unit is installed in a threaded hole
that penetrates a coolant passage of the engine.
High sending unit resistance causes low coolant temperature gauge readings. Low sending unit resistance causes high coolant temperature gauge
readings. The sending unit resistance values are shown in a chart in Specifications.
CIRCUIT OPERATION
Circuit G20 connects the engine coolant temperature gauge to the engine coolant temperature sensor. The sensor is a variable resistor and case
grounded to the engine. Circuit F14 from fuse 12 in the fuse block connects to the instrument cluster and supplies voltage for the gauge.
As current flows through the coils in the gauge, it creates a magnetic field. One of the coils in the gauge receives fixed current. The other coil is
connected to the temperature gauge on circuit G20. A change in temperature changes the resistance in the sensor, which alters the current flow
through the second coil in the gauge. A change in current flow alters the magnetic field in the gauge, which changes the pointer position.
