RAM 1500 Truck 2WD V6-3.9L VIN X (1999)
Coolant Temperature Sensor/Switch (For Computer): Description and Operation
Engine Coolant Temperature Sensor (Typical)
ENGINE COOLANT TEMPERATURE SENSOR-PCM INPUT
The Engine Coolant Temperature (ECT) sensor is installed into a water jacket at the front of the intake manifold located near the rear of the
generator. The sensor provides an input voltage to the powertrain control module (PCM) relating coolant temperature. The PCM uses this input
along with inputs from other sensors to determine injector pulse width and ignition timing. As coolant temperature varies, the coolant temperature
sensor resistance will change. This change in resistance results in a different input voltage to the PCM.
When the engine is cold, the PCM will operate in Open Loop cycle. It will demand slightly richer air-fuel mixtures and higher idle speeds. This is
done until normal operating temperatures are reached.
