HVAC Systems - Automatic Diagnosis

CIRCUIT DESCRIPTION
The instrument panel integration module (IPM) communicates with the HVAC control module through the HVAC control module assembly data signal and HVAC control module clock signal. This communication link is only used by the IPM and the HVAC control module.

CONDITIONS FOR RUNNING THE DTC
The ignition is turned ON.

CONDITIONS FOR SETTING THE DTC
^ There is a loss of communications between the IPM and the HVAC control module.
^ The above conditions are present for 3 seconds.

ACTION TAKEN WHEN THE DTC SETS
The HVAC system will be disabled.

CONDITIONS FOR CLEARING THE DTC
^ The DTC will become history if the IPM no longer detects a failure.
^ The history DTC will clear after 50 fault-free ignition cycles.
^ Use the scan tool in order to clear the DTCs.

TEST DESCRIPTION

Steps 1-7:

Steps 8-19:

The numbers below refer to the step numbers on the diagnostic table.
4. This step verifies that the HVAC control module is functioning, but not communicating with the IPM.