Grand Cherokee 2WD V8-4.7L VIN N (2000)
Ambient Temperature Sensor / Switch HVAC: Description and Operation
Ambient air temperature is monitored by the Electronic Vehicle Information Center (EVIC) through ambient temperature messages received from the
Body Control Module (BCM) over the Programmable Communications Interface (PCI) data bus network. The BCM receives a hard wired input from
the ambient temperature sensor. The ambient temperature sensor is a variable resistor mounted to a bracket that is secured with a screw to the right side
of the headlamp mounting module grille opening, behind the radiator grille and in front of the engine compartment.
The ambient temperature sensor is a variable resistor that operates on a five-volt reference signal sent to it by the BCM. The resistance in the sensor
changes as temperature changes, changing the temperature sensor signal circuit voltage to the BCM. Based upon the resistance in the sensor, the BCM
senses a specific voltage on the temperature sensor signal circuit, which it is programmed to correspond to a specific temperature. The BCM then sends
the proper ambient temperature messages to the EVIC over the PCI data bus.
