P1538

Circuit Description
This diagnostic test indicates if the Air Conditioning (A/C) request circuit is shorted to voltage. This is done by comparing the A/C Request line (CKT 603) to the serial data received from the HVAC controller. If A/C is not requested by serial data and the A/C Request line (CKT 603) is high, voltage present, then DTC P1538 is set.

Conditions for Running the DTC
^ DTC P1605 not set.
^ A/C compressor not requested by the HVAC programmer via serial data.

Conditions for Setting the DTC
A/C request line high continuously for 20 seconds.

Action Taken When the DTC Sets
Disable the A/C compressor.
^ The Malfunction Indicator Lamp (MIL) will not illuminate.
^ No message will be displayed.

Conditions for Clearing the DTC
^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.
^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not tail.
^ Use a scan tool to clear DTCs.
^ Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended.