Ambient Temperature Sensor

AMBIENT TEMPERATURE SENSOR FAULT CODES
The outside temperature function is supported by the ambient temperature sensor (ATS), a signal and ground circuit hardwired to the FCM, and the CMTC/EVIC display.

If the CMTC/EVIC display indicates 54° C (130° F) or the ATS sense circuit is shorted to ground, the temp display will be 54° C (130° F) to indicate a SHORT circuit condition.

If the CMTC/EVIC display indicates -40° C (-40 ° F) or the ATS sense circuit is open, the temp display will be -40° C (-40° F) to indicate an OPEN circuit condition.

If there is an OPEN or SHORT circuit condition, it must be repaired before the CMTC/EVIC VFD can be tested.

The ATS is supported by the FCM. Ambient Temperature Sensor DTC's will be recorded in the FCM. The ATS can be diagnosed using the following Sensor Test. Test the ATS circuits using the diagnostics in the Body Diagnostic Procedures Manual. If the EVIC passes the self test, and the ATS, the circuits, and PCI bus communications are confirmed to be OK, but the EVIC temperature display is inoperative or incorrect, replace the FCM.

AMBIENT TEMPERATURE SENSOR TEST
1. Turn the ignition OFF.
2. Disconnect the ATS harness connector.
3. Measure the resistance of the ATS using the following min/max 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 values are not OK, replace the Sensor.