P1538

Circuit Description

This diagnostic test indicates if the 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 Setting the DTC

Test Conditions

^ DTC P1605 not set.

^ A/C compressor not requested by the HVAC programmer via serial data.

Failure Condition

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 nonemission related diagnostic test.

^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

^ PCM battery voltage is interrupted.

^ Using a Scan tool.