Displayed Input Status - HVAC System - Dual Zone

The scan tool's input display function can be helpful in determining if the Instrument Panel Cluster (IPC) is receiving the correct input status. This can assist in determining if a system is seeing a system operate as intended. For example, the IPC requires the door ajar switch status from the Body Control Module (BCM) to display the DOOR AJAR message. If the DOOR AJAR message is always displayed, a starting point might be selecting the BCM door ajar input diagnostic function from the scan tool menu. The input status will be displayed as ACTIVE or INACTIVE. If, again using the door ajar switch input to the BCM as an example, if the BCM door ajar input display mode was entered with the door open the scan tool would display ACTIVE. If the door is then closed the scan tool display would change to show INACTIVE. If the input state display never changes when a system is operated, that system could be malfunctioning. If the display input is constantly ACTIVE never changing to INACTIVE, or INACTIVE never changing to ACTIVE, the input could be stuck . This could be caused by a short, open or malfunctioning switch, or in rare instances the BCM itself. Check if the IPC is receiving the correct input information from the Body Control Module (BCM). If the BCM is receiving the correct input information, then perform the same procedure using the IPC to determine if the IPC is actually able to receive this input information on the serial data line from the BCM. If the IPC recognizes the door is close, but still displays the DOOR AJAR message, the IPC requires additional diagnosis. This example can be applied to an indicator malfunction or other warning messages displayed as well as other IPC malfunctions.