Test Procedure

DS1 DTC P0533, P1461: CHECK THE ACP V PID

Key in ON position.
Access the PCM and monitor the ACP V PID.

Is the voltage less than 4.9 V?

Yes	No
Key in OFF position. The ACP voltage is now below maximum. GO to DS15.	Key in OFF position. A hard fault is present. GO to DS2.

DS2 CHECK THE VOLTAGE BETWEEN THE VREF AND SIGRTN CIRCUITS AT THE ACP SENSOR VEHICLE HARNESS CONNECTOR

ACP Sensor connector disconnected.
Key in ON position.
Measure the voltage between:

( + ) ACP Sensor Connector, Harness Side	( - ) ACP Sensor Connector, Harness Side
VREF - Pin 2	SIGRTN - Pin 1

Is the voltage between 4 V - 6 V?

Yes	No
GO to DS3.	Key in OFF position. GO to PINPOINT TEST C step 1 .

DS3 CHECK THE ACP CIRCUIT FOR A SHORT TO VREF

Diagnostic tool connector disconnected.
PCM connector disconnected.
Measure the resistance between:

( + ) ACP Sensor Connector, Harness Side	( - ) ACP Sensor Connector, Harness Side
ACP - Pin 3	VREF - Pin 2

Is the resistance greater than 10K ohms?

Yes	No
GO to DS4.	REPAIR the short circuit to VREF. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS4 CHECK THE ACP CIRCUIT FOR A SHORT TO POWER IN THE HARNESS

Key in ON position.
Measure the voltage between:

( + ) ACP Sensor Connector, Harness Side	( - )
ACP - Pin 3	Ground

Is the voltage less than 1 V?

Yes	No
Key in OFF position. GO to DS5.	REPAIR the short circuit to PWR. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS5 CHECK FOR AN OPEN ACP CIRCUIT IN THE HARNESS

Measure the resistance between:

( + ) ACP Sensor Connector, Harness Side	( - ) PCM Connector, Harness Side
ACP - Pin 3	ACP

Is the resistance less than 5 ohms?

Yes	No
Key in OFF position. GO to DS6.	REPAIR the open circuit. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS6 CHECK THE PCM OUTPUT

NOTE: If a diagnostic tool communication concern exists, follow the NO answer.

PCM connector connected.
Connect a 5 amp fused jumper wire between the following:

Point A ACP Sensor Connector, Harness Side	Point B ACP Sensor Connector, Harness Side
ACP - Pin 3	SIGRTN - Pin 1

Key in ON position.
Access the PCM and monitor the ACP V PID.

Is the voltage less than 4.9 V?

Yes	No
Key in OFF position. INSTALL a new ACP sensor. REFER to the appropriate CLIMATE CONTROL SYSTEM article to the diagnose symptom. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.	INSTALL a new PCM. Refer to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM . START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS7 DTC P0532, P1462: CHECK THE ACP V PID

Key in ON position.
Access the PCM and monitor the ACP V PID.

Is the voltage greater than 0.15 V?

Yes	No
To determine if an intermittent condition exists. GO to DS15.	Key in OFF position. A hard fault exists, GO to DS8.

DS8 CHECK THE VOLTAGE BETWEEN THE VREF AND SIGRTN CIRCUITS AT THE ACP SENSOR VEHICLE HARNESS CONNECTOR

ACP Sensor connector disconnected.
Key in ON position.
Measure the voltage between:

( + ) ACP Sensor Connector, Harness Side	( - ) ACP Sensor Connector, Harness Side
VREF - Pin 2	SIGRTN - Pin 1

Is the voltage between 4 V - 6 V?

Yes	No
Key in OFF position. GO to DS9.	Key in OFF position. VREF is out of range, GO to PINPOINT TEST C step 1 .

DS9 SIMULATE AN OPPOSITE SIGNAL TO THE PCM ACP

Connect a 5 amp fused jumper wire between the following:

Point A ACP Sensor Connector, Harness Side	Point B ACP Sensor Connector, Harness Side
VREF - Pin 2	ACP - Pin 3

Key in ON position.
Access the PCM and monitor the ACP V PID.

Is the voltage greater than 4 V?

Yes	No
Key in OFF position. INSTALL a new ACP sensor. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.	GO to DS10.

DS10 CHECK THE ACP CIRCUIT FOR SHORT TO GND

Key in OFF position.
Diagnostic tool connector disconnected.
PCM connector disconnected.
Measure the resistance between:

Is the resistance greater than 10K ohms?

( + ) ACP Sensor Connector, Harness Side	( - )
ACP - Pin 3	Ground

Is the resistance greater than 10K ohms?

Yes	No
GO to DS11.	REPAIR the short circuit. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS11 CHECK THE ACP CIRCUIT FOR SHORT TO SIGRTN

Measure the resistance between:

( + ) ACP Sensor Connector, Harness Side	( - ) ACP Sensor Connector, Harness Side
ACP - Pin 3	SIGRTN - Pin 1

Is the resistance greater than 10K ohms?

Yes	No
GO to DS12.	REPAIR the short circuit. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS12 CHECK THE ACP CIRCUIT FOR AN OPEN IN THE HARNESS

Measure the resistance between:

( + ) ACP Sensor Connector, Harness Side	( - ) PCM Connector, Harness Side
ACP - Pin 3	ACP

Is the resistance less than 5 ohms?

Yes	No
GO to DS13.	Key in OFF position. REPAIR the open circuit. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS13 CHECK FOR THE A/CC TO ENGAGEPCM

connector connected.
ACP Sensor connector connected.
Key on engine running.
While listening for the A/C clutch to engage, turn the A/C on. Repeat if necessary.

Did the A/C engage when the A/C was turned on?

Yes	No
Key in OFF position. INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM . START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.	GO to DS14.

DS14 VERIFY THE A/C SYSTEM FUNCTION, INCLUDING REFRIGERANT CHARGE

RESTORE vehicle.
Verify the A/C system function, including refrigerant charge. Go to the appropriate CLIMATE CONTROL SYSTEM article.

Does the A/C have a refrigerant charge?

Yes	No
Key in OFF position. INSTALL a new PCM. REFER to FLASH ELECTRICALLY ERASEABLE PROGRAMMABLE READ ONLY MEMORY - FLASH EEPROM . START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.	Key in OFF position. REFER to the appropriate CLIMATE CONTROL SYSTEM article to check the A/C system pressure, to test the ACCS cycle times, and to check the causes of fast ACCS cycling. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.

DS15 CHECK THE ACP CIRCUIT FOR AN INTERMITTENT CONCERN

Key in ON position.
Access the PCM and monitor the ACP V PID.
Observe the PCM ACP V PID for an indication of a fault while completing the following. Note that a fault is indicated by a sudden change in voltage.
Shake, wiggle, and bend the ACP, SIGRTN, and VREF wires between the ACP sensor and PCM circuit(s).
Lightly tap on the ACP sensor to simulate road shock.

Is a fault indicated?

Yes	No
REPAIR the open circuit. CLEAR the DTCs. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.	GO to PINPOINT TEST Z step 1 .

DS16 DTC P1463: VERIFY THE A/C CLUTCH CAN DISENGAGE

A/C and defroster off.
Key on engine running.
Verify the A/C clutch can disengage.

Is the A/C clutch disengaged?

Yes	No
Key in OFF position. GO to DS17.	Concern is elsewhere. RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE for further direction.

DS17 CHECK FOR VOLTAGE AND GROUND TO THE A/C CLUTCH USING A NON-POWERED TEST LAMP

NOTE: If voltage and ground to the A/C clutch have already been checked or the A/C clutch can be heard clicking ON when the A/C is turned ON, GO to the question at the end of this test step.

A/CCS Switch connector disconnected.
Connect a jumper wire in the A/C low pressure cycling switch harness connector to complete the circuit.
A/CC Assembly connector disconnected.
Connect a non-powered test lamp between the power pin and ground pin at the A/C clutch harness connector.
Key on engine running.
Turn on the A/C, and wait 15 seconds.
Monitor the test lamp.
Reconnect the A/C clutch and the A/C cycling switch when done testing.

Does the lamp light, or can the A/C clutch be heard clicking on?

Yes	No
GO to DS18.	REFER to the appropriate CLIMATE CONTROL SYSTEM article to the diagnose symptom.

DS18 CHECK IF A SUFFICIENT A/C PRESSURE CHANGE CAN BE DETECTED BY THE ACP V PID

Key on engine running.
A/C and defroster off.
Access the PCM and monitor the ACP V PID.
Monitor the PCM-ACP V PID voltage.
A/C and defroster on.
Five seconds after A/C clutch engagement, note the voltage. If the clutch does not engage, follow the NO answer instructions.

Did the PCM-ACP V PID change more than 0.3 volt within 5 seconds of clutch engagement?

Yes	No
Key in OFF position. GO to DS19.	Key in OFF position. A/C OFF. GO to DS20.

DS19 DTC P1463: CHECK FOR THE PRESENCE OF DTC

Are both the symptom and DTC P1463 present?

Yes	No
REFER to the appropriate CLIMATE CONTROL SYSTEM article.	Concern is elsewhere. RETURN to SYMPTOM CHARTS - CNG, FLEX-FUEL & GASOLINE for further direction.

DS20 CHECK THE A/C SYSTEM PRESSURE AND PRESSURE CHANGE

INSTALL an A/C system manifold gauge set and check the A/C system high pressure reading.
Key on engine running.
A/C and defrost off.
Note the A/C high pressure reading.
While monitoring the A/C system high pressure reading, turn the A/C on. Five seconds after clutch engagement, note the pressure (the pressure should increase).
A/C and defrost off.

Did the A/C high pressure reading change more than 207 kPa (30 psi) within 5 seconds of clutch engagement?

Yes	No
GO to DS21.	Key in OFF position. REFER to the appropriate CLIMATE CONTROL SYSTEM article.

DS21 CHECK THE VOLTAGE BETWEEN THE VREF AND SIGRTN CIRCUITS AT THE ACP SENSOR VEHICLE HARNESS CONNECTOR

ACP Sensor connector disconnected.
Key in ON position.
Measure the voltage between:

( + ) ACP Sensor Connector, Harness Side	( - ) ACP Sensor Connector, Harness Side
VREF - Pin 2	SIGRTN - Pin 1

Is the voltage between 4 V - 6 V?

Yes	No
Key in OFF position. GO to DS22.	GO to PINPOINT TEST C step 1 .

DS22 CHECK THE ACP CIRCUIT FOR AN OPEN IN THE HARNESS

PCM connector disconnected.
Measure the resistance between:

( + ) ACP Sensor Connector, Harness Side	( - ) PCM Connector, Harness Side
ACP - Pin 3	ACP

Is the resistance less than 5 ohms?

Yes	No
Key in OFF position. INSTALL a new ACP sensor.	Key in OFF position. REPAIR the open circuit. START the engine. TURN the A/C on. WAIT 15 seconds then turn the A/C off. RERUN the Quick Test.