Liberty Sport 4WD L4-2.4L VIN 1 (2002)
Road Temperature Sensor: Description and Operation
Fig. 10 Ambient Temperature Sensor
AMBIENT TEMP SENSOR
Ambient air temperature is monitored by the Compass Mini-Trip Computer (CMTC) through ambient temperature sensor 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 in front the radiator, behind the grille,
near the center of the vehicle.
Refer to Body Control Module in Electronic Control Modules. For complete circuit diagrams, refer to the appropriate wiring information. The
ambient temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
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 CMTC over the PCI data bus.
The thermometer function is supported by the ambient temperature sensor, a wiring circuit, the Body Control Module (BCM), the Programmable
Communications Interface (PCI) data bus, and a portion of the Compass Mini-Trip Computer module.
The ambient temperature sensor circuit can also be diagnosed by referring to Diagnosis and Testing - Ambient Temperature Sensor, and Diagnosis
and Testing - Ambient Temperature Sensor Circuit. If the temperature sensor and circuit are confirmed to be OK, but the temperature display is
inoperative or incorrect, refer to Diagnosis and Testing - Compass Mini-Trip Computer in this section. For complete circuit diagrams, refer to the
appropriate wiring information.
