P1542

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

This diagnostic detects an over temperature/over pressure condition in the A/C system. The DTC will be set if the high pressure switch disables the A/C clutch and the high side temperature is above a threshold. Under extremely hot ambient conditions a rapid cycling situation could occur as this DTC is set and cleared. To protect the A/C system, if this DTC continues to set and clear, a lower high side temperature will be used to clear the DTC. If after this occurs a rapid cycling condition is still detected a third, lower temperature is used to clear the malfunction DTC and re-enable the A/C clutch.

CONDITIONS FOR RUNNING THE DTC

DTC P1535 not set.

CONDITIONS FOR SETTING THE DTC

^ DTC P1542 is not current.

^ A/C disabled by high pressure switch.

^ High side temperature 87°C (189°F) or higher.

OR

^ DTC P1542 is current.

^ A/C disabled by high pressure switch.

^ If State 0-high side temperature is 82°C (180°F) or higher.

^ If State 1-high side temperature is 79°C (174°F) or higher.

^ If State 2-high side temperature is 76°C (169°F) or higher.

- State 1 occurs when state 0 is active and DTC P1542 has set 10 times or more in 30 seconds.

- State 2 occurs when the state 1 is active and DTC P1542 has set more than 15 times in 30 seconds. The DTC P1542 counter and timer will be reset to 0 on any state transition.

- After each power up, state 0 is the initial active state. If, during the ignition cycle, the state should progress to state 2, it is to remain in state 2 for the duration of the ignition cycle.


ACTION TAKEN WHEN THE DTC SETS

^ Disengage the A/C compressor.

^ 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.

^ PCM battery voltage is interrupted.

^ Using a Scan tool.

DIAGNOSTIC AIDS

This DTC is used for system protection during a high temperature / pressure condition. This condition could occur normally if sufficient cooling of the A/C system cannot occur due to high ambient temperature.


TEST DESCRIPTION

Number(s) below refer to the step number(s) on the Diagnostic Table.

2. If the outside temperature was not excessive when the DTC set, than the A/C system experienced an overheating / high pressure condition and should be diagnosed in the Heating and Air Conditioning.