A/C Pressure Sensor (ACP) Malfunction

NOTE: The following test procedures are for DTCs P1461, P1462 and P1463.

Fig 1: A/C Pressure Sensor (ACP) Malfunction Detection Condition Possible Cause

Courtesy of MAZDA MOTORS CORP.

A/C PRESSURE SENSOR (ACP) MALFUNCTION INSPECTION/ACTION CHART

STEP	INSPECTION		ACTION
1	CHECK FOR PRESENT DTCS Connect the WDS or equivalent tester. Key ON, Engine OFF (KOEO). Is DTC P1461 or P1462 present?	Yes	If DTC P1461 is present, go to next step If DTC P1462 is present, go to step 7.
1		No	Concern is not present at this time.
2	DTC P1461: Check ACP V PID Connect the WDS or equivalent tester. Key ON, Engine OFF (KOEO). Access ACP V PID. Is ACP V PID less than 4.9 volts?	Yes	The ACP circuit voltage is now below the maximum. Go to step 14.
2		No	Key OFF. Go to next step.
3	CHECK VOLTAGE BETWEEN VREF AND SIG RTN CIRCUITS TO ACP SENSOR NOTE: Verify that A/C and defrost were OFF during Self-Test. If A/C or defrost were on, turn off and rerun Self-Test. Disconnect ACP sensor. Key ON, Engine OFF (KOEO). Measure the voltage between VREF (B/Y) and SIG RTN (DG/O) circuits at the ACP sensor harness connector. Is voltage between 4.0 and 6.0 volts?	Yes	Go to next step.
3		No	VREF is out-of-range or SIG RTN circuit to ACP sensor is open. REPAIR the circuit and retest.
4	INDUCE OPPOSITE ACP SIGNAL Key ON, Engine OFF (KOEO). Access ACP V PID. Is ACP PID now less than 4.9 volts?	Yes	Key OFF. INSTALL a new ACP sensor. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
4		No	Go to next step.
5	CHECK ACP CIRCUIT FOR SHORT TO VREF IN HARNESS Disconnect the WDS or equivalent tester. Disconnect PCM. Measure resistance between ACP (R/Y) and VREF (B/Y) circuits at the ACP sensor harness connector. Is the resistance greater than 10,000 ohms?	Yes	Go to next step.
5		No	REPAIR short circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
6	CHECK ACP CIRCUIT FOR SHORT TO POWER IN HARNESS Key ON, Engine OFF (KOEO). Measure voltage between ACP (R/Y) circuit at the ACP sensor vehicle harness connector and chassis ground. Is voltage less than 1.0 volt?	Yes	INSTALL a new PCM. See POWERTRAIN CONTROL MODULE (PCM) . START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
6		No	REPAIR short circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
7	DTC P1462: CHECK ACP V PID Connect the WDS or equivalent tester. Key ON, Engine OFF (KOEO). Access ACP V PID. Is ACP V PID greater than 0.15 volts?	Yes	The ACP circuit voltage is now above the minimum. Go to step 14.
7		No	Key OFF. Go to next step.
8	CHECK VOLTAGE BETWEEN VREF AND SIG RTN TO ACP SENSOR Disconnect the ACP sensor. Key ON, Engine OFF (KOEO). Measure the voltage between VREF (B/Y) and SIG RTN (DG/O) circuits at the ACP sensor harness connector. Is voltage between 4.0 and 6.0 volts?	Yes	Go to next step.
8		No	VREF is out-of-range or SIG RTN circuit to ACP sensor is open. REPAIR the circuit and retest.
9	INDUCE OPPOSITE ACP SIGNAL Connect a jumper wire between ACP (R/Y) and VREF (B/Y) circuits at the ACP sensor harness connector. Key ON, Engine OFF (KOEO). Access ACP V PID. Is ACP PID now less than 4.0 volts?	Yes	Key OFF. INSTALL a new ACP sensor. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
9		No	Go to next step.
10	CHECK ACP CIRCUIT FOR SHORT TO POWER, GROUND OR SIG RTN IN HARNESS Key OFF. Disconnect the WDS or equivalent tester. Measure the resistance between ACP (R/Y) and SIG RTN (DG/O) circuits at the ACP sensor harness connector. Measure the resistance between the ACP (R/Y) circuit at the ACP sensor harness connector and the battery. Are both resistances greater than 10,000 ohms?	Yes	Go to next step.
10		No	REPAIR the short circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
11	CHECK ACP CIRCUIT FOR OPEN HARNESS NOTE: See the PCM connector pin numbers in the beginning of this pinpoint test. Measure the resistance between ACP (R/Y) and SIG RTN (DG/O) circuits at the ACP sensor harness connector. Measure resistance of ACP (R/Y) circuit between PCM harness connector pin and the ACP sensor harness connector. Is the resistance less than 5 ohms?	Yes	Go to next step.
11		No	REPAIR the short circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
12	CHECK FOR THE A/C CLUTCH TO ENGAGE Reconnect ACP connector. Key ON, Engine OFF (KOEO). While listening for the A/C clutch to engage, turn the A/C on. Repeat if necessary. Key OFF. Did the A/C clutch engage when the A/C was turned on?	Yes	INSTALL a new PCM. See POWERTRAIN CONTROL MODULE (PCM) . START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
12		No	Go to next step.
13	VERIFY A/C SYSTEM HAS A REFRIGERANT CHARGE Restore the vehicle. Verify that the A/C system has a refrigerant charge. Does the A/C system have a refrigerant charge?	Yes	INSTALL a new PCM. See POWERTRAIN CONTROL MODULE (PCM) . START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
13		No	REPAIR the A/C system. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
14	CHECK FOR INTERMITTENT ACP CIRCUIT FAULT Key ON, Engine OFF (KOEO). Access ACP V PID. NOTE: A fault will be indicated by a sudden change in ACP V PID voltage. Observe ACP V PID for an indication of a fault while completing the following. Shake, wiggle, bend the ACP SIG RTN and VREF circuits between the ACP sensor and the PCM. Lightly tap on the ACP sensor to simulate road shock. Is a fault indicated?	Yes	INSTALL a new PCM. See POWERTRAIN CONTROL MODULE (PCM) . START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
14		No	Unable to duplicate or identify fault at this time. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
15	DTC 1463: VERIFY A/C CLUTCH CAN DISENGAGE A/C and defroster OFF. Start engine. Verify that the A/C clutch disengages. Is the A/C clutch disengaged?	Yes	Key OFF. Go to next step.
15		No	Go to SYMPTOM TROUBLESHOOTING CHART -- AIR CONDITIONING (A/C) .
16	CHECK FOR VOLTAGE AND GROUND TO A/C CLUTCH (USING NON-POWERED TEST LAMP) NOTE: If voltage and ground to A/C clutch has 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. Disconnect the cycling switch. Install a jumper wire in the A/C cycling switch vehicle harness connector to complete the circuit. Disconnect the A/C clutch. Connect a non-powered test lamp between the power pin and ground pin at the A/C clutch vehicle harness connector. Start the engine. Turn A/C ON, wait 15 seconds. Monitor the test lamp. After testing, turn the key OFF, remove the jumper wire and reconnect A/C cycling switch. Does the test lamp light (or can the A/C clutch be heard clicking on)?	Yes	Go to next step.
16		No	GO to SYMPTOM TROUBLESHOOTING CHART -- AIR CONDITIONING (A/C) .
17	CHECK IF A SUFFICIENT A/C PRESSURE CHANGE CAN BE DETECTED BY THE ACP PID Start the engine. A/C OFF. Access ACP V PID. Note ACP V PID voltage. While monitoring ACP V PID voltage, turn the A/C on. Five seconds after A/C clutch engagement, note the voltage. NOTE: If the clutch does not engage, follow NO Action. Did the ACP V PID voltage change more than 0.3 volt within five seconds of clutch engagement?	Yes	GO to SYMPTOM TROUBLESHOOTING CHART -- AIR CONDITIONING (A/C) .
17		No	Go to next step.
18	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 readings. Start engine. A/C 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 OFF. Did the A/C high pressure reading change more than 207 kPa (30 psi) within five seconds of clutch engagement?	Yes	Go to next step.
18		No	GO to SYMPTOM TROUBLESHOOTING CHART -- AIR CONDITIONING (A/C) .
19	CHECK VOLTAGE BETWEEN VREF AND SIG RTN TO ACP SENSOR Disconnect the ACP sensor. Key ON, Engine OFF (KOEO). Measure the voltage between VREF (B/Y) and SIG RTN (DG/O) circuits at the ACP sensor harness connector. Is voltage between 4.0 and 6.0 volts?	Yes	Go to next step.
19		No	VREF is out-of-range. GO to TEST 1: VEHICLE REFERENCE VOLTAGE (VREF) .
20	CHECK ACP CIRCUIT FOR OPEN IN SENSOR Key OFF. ACP sensor disconnected. Disconnect PCM. Measure the resistance of ACP (R/Y) circuit between PCM harness connector pin and the ACP sensor harness connector. Is resistance less than 5.0 ohms?	Yes	INSTALL a new ACP sensor. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.
20		No	REPAIR open circuit. START engine. TURN A/C on, WAIT 15 seconds then TURN A/C off. RERUN Self-test.