Theory Of Operation

This diagnostic checks the validity and availability of the ambient temperature signal which is sent by the Body Controller Module (BCM) via a CAN message. The diagnostic checks the validity by verifying the received value is in the range between a lower and upper calibrated threshold. The diagnostic also checks the availability by verifying the received value is not equal to the Signal Not Available (SNA) default value. When the ambient temperature signal is invalid or missing, the diagnostic will set a fault in the Transmission Control Module (TCM).