PT Cruiser L4-2.4L Turbo VIN 8 (2005)
avoid "hot soak" condition readings. The displayed outside temperature information is stored within the memory of the compass/temp mirror. When the
Compass/Temp Mirror is first powered up, it retrieves the temperature data from the module memory. The memory temperature is compared with the
temperature received from the ambient temperature sensor. The colder of the two temperatures is displayed.
TEMPERATURE UPDATE - WARM
On power up, when the outside temperature sensed by the ambient temperature sensor is warmer than the temperature stored in the module memory, the
Compass/Temp Mirror will update the displayed temperature in relation to vehicle speed and engine temperature data received on the PCI Bus.
TEMPERATURE UPDATE - COLD
On power up, when the outside air temperature sensed by the ambient temperature sensor is colder than the stored memory temperature, the
Compass/Temp Mirror will update the displayed temperature to the outside temperature at a rate of -1° F every 2 seconds, regardless if the vehicle is
moving or not.
EXTREME TEMPERATURE/OPEN OR SHORT CONDITION
If the measured outside temperature is more than 60° C (140° F) or the ambient temperature sensor sense circuit is shorted to ground, the temp display
will be 60° C (140° F) to indicate a short circuit condition.
If the measured outside temperature is less than -45° C (-49° F) or the ambient temperature sensor sense circuit is open, the temp display will be -45° C
(-49° F) to indicate an open circuit condition.
AMBIENT TEMPERATURE SENSOR
DESCRIPTION
The Ambient Temperature Sensor is hardwired to the PCM. The ambient air temperature is monitored and displayed by the Compass/Temp Mirror.
The ambient temperature sensor cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
OPERATION
The resistance in the ambient temperature sensor changes as the outside temperature rises or falls. The PCM senses the change in reference voltage
through the ambient temperature sensor resistor. Based on the resistance of the ambient temperature sensor, the PCM is programmed to correspond to a
specific temperature. The Compass/Temp Mirror then displays the proper ambient temperature.
AMBIENT TEMPERATURE SENSOR DIAGNOSTICS
The outside temperature function is supported by the ambient temperature sensor, a signal and ground circuit hardwired to the PCM and the
Compass/Temp Mirror display.
If the Compass/Temp Mirror display indicates 60° C (140° F) or the ambient temperature sensor sense circuit is shorted to ground, the temp display will
be 60° C (140° F) to indicate a SHORT circuit condition.
If the Compass/Temp Mirror display indicates -45° C (-49° F) or the ambient temperature sensor sense circuit is open, the temp display will be -45° C
(-49° F) to indicate an OPEN circuit condition.
If there is an OPEN or SHORT circuit condition, it must be repaired before the Compass/Temp Mirror VF display can be tested.
The ambient temperature sensor can be diagnosed using the following Sensor Test. If there are no codes stored in the PCM and the ambient temperature
sensor and the circuits are confirmed to be OK, but the temperature display is inoperative or incorrect, replace the Compass/Temp Mirror.
AMBIENT TEMPERATURE SENSOR TEST
1. Turn the ignition OFF.
2. Disconnect and isolate the battery negative cable.
3. Disconnect the ambient temperature sensor harness connector.
4. Measure the resistance of the ambient temperature sensor using the following values:
-
0° C (32° F) Sensor Resistance = 29.33 - 35.99 Kilohms
-
10° C (50° F) Sensor Resistance = 17.99 - 21.81 Kilohms
-
20° C (68° F) Sensor Resistance = 11.37 - 13.61 Kilohms
-
25° C (77° F) Sensor Resistance = 9.12 - 10.86 Kilohms
-
30° C (86° F) Sensor Resistance = 7.37 - 8.75 Kilohms
-
40° C (104° F) Sensor Resistance = 4.90 - 5.75 Kilohms
The sensor resistance should read between these min/max values. If the resistance value is OK, refer to the Wiring Diagrams to rest the Signal and
Ground circuits. If the resistance values are not OK, replace the Sensor.
