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 Setting the DTC
Test Condition
DTC P1535 not set.
Failure Conditions
| • | DTC P1542 is not current. |
| • | A/C disabled by high pressure switch. |
| • | High side temperature 87°C (189°F) or higher. |
| • | 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. |
| • | 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 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.
-
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 Section 1.
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
|
- Turn the key ON.
- Using a scan tool select the Failure Rec. for DTC P1542 and check
the Outside Air Temp. display when the DTC set.
Was the outside temperature exceedingly hot?
| --
| System OK. Refer to Diagnostic Aids
| Go to Section 1, Heating and Air Conditioning
|
