Viper RT-10 V10-8.0L VIN E (1997)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Fig. 6 Engine Coolant Temperature Sensor
ENGINE COOLANT TEMPERATURE SENSOR-PCM INPUT
The engine coolant temperature sensor threads into the front of the driver side cylinder head (Fig. 6). The sensor provides an input to the PCM. As
coolant temperature varies, the sensor resistance changes, resulting in a different input voltage to the PCM.
Until the engine reaches operating temperature, the PCM demands slightly richer air-fuel mixtures and higher idle speeds.
This sensor is also used for cooling fan control and A/C cutoff at high coolant temperatures.
This 3-way sensor is also used for the water temperature gauge and dashboard warning light.
CIRCUIT OPERATION
The engine coolant temperature sensor provides an input to the Powertrain Control Module (PCM) on circuit K2. This vehicle uses a combination
sensor for the instrument cluster coolant temperature gauge.
From circuit K2, the engine coolant temperature sensor draws up to 5 volts from the PCM. The sensor is a variable resistor. As coolant
temperature changes the resistance in the sensor changes, causing a change in current draw. The K2 circuit connects to cavity A16 of the PCM
connector. The PCM provides a ground for the engine coolant temperature sensor signal (circuit K2) through circuit K4. Circuit K4 connects to
cavity A4 of the PCM.
When the engine coolant temperature is above a pre-determined temperature, contacts in the engine coolant temperature sensor/sending unit
CLOSE and circuit G2, from the lamp, is connected to ground through the case grounded switch.
