GM Service Manual Online
For 1990-2009 cars only

Circuit Description

This diagnostic test monitors the ECT sensor for a high engine temperature condition. If a high engine temperature condition exists it will either disable A/C compressor if engaged or not allow compressor operation if requested during the high engine temperature condition. After the diagnostic test fails and is set current it uses a lower temperature cutoff point to ensure that the A/C system won't be a load on the cooling system during conditions of high engine temperature.

Conditions for Setting the DTC

Test Condition

DTCs P0117, P0118 not set.

Failure Conditions

    •  A/C Compressor operation requested by HVAC controller.
    •  Coolant temperature is greater than 125°C (257°F).
    •  DTC P1536 not current.
        OR
    •  A/C Compressor operation requested or not requested by HVAC controller.
    •  Coolant temperature greater than 120°C (248°F).
    •  DTC P1536 current.

Action Taken When the DTC Sets

    •  A/C compressor is disengaged.
    •  The Malfunction Indicator Lamp (MIL) will not illuminate.
    •  The PCM will command a message to be displayed.
    •  The PCM may record operating conditions at the time the diagnostic fails. This information will be stored in the Failure Records.

Conditions for Clearing the Message/DTC

    •  The PCM will turn the message OFF after one run and pass of the diagnostic test.
    •  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 fail.
    • Use a scan tool to clear DTCs.
    • Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

Diagnostic Aids

This DTC is associated with an overheating/low coolant level condition. Refer to cooling system for diagnosis.

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check

2

Connect the scan tool.

Are DTCs P0116, P0117 or P1114 also set?

--

Go to DTCs that are set

Refer to Diagnostic Aids