2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P0532-A/C PRESSURE SENSOR CIRCUIT LOW

P0532-A/C PRESSURE SENSOR CIRCUIT LOW

For a complete wiring diagram, refer to the Wiring Information.


Theory of Operation

The A/C pressure transducer monitors the pressures in the high side of the A/C refrigerant system through its connection to a fitting on the A/C discharge line and its internal resistance changes in response to the pressures it monitors. The Totally Intergrated Power Module (TIPM) provides a five Volt reference signal and a sensor ground to the A/C pressure transducer, then monitors the output voltage of the transducer on a sensor return circuit to determine refrigerant pressure the TIPM busses the reading to PCM. The PCM is programmed to respond to this and other sensor inputs by controlling the operation of the A/C clutch and the radiator cooling fan to help optimize A/C system performance and to protect the A/C system components from damage. The PCM will request disengagement of the A/C clutch when high side pressure rises above 3219 kPa (476 psi) and re-engage the clutch when high side pressure drops below 2937 kPa (426 psi). The PCM will also disengage the A/C clutch if the high side pressure drops below 110 kPa (16 psi) and will re-engage the clutch when the high side pressure rises above 220 kPa (32 psi). When the refrigerant pressure rises above 1655 kPa (240 psi), the PCM will actuate the cooling fan.


Possible Causes

(C818) A/C PRESSURE SENSOR SUPPLY CIRCUIT SHORTED TO GROUND
(C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
(C818) A/C PRESSURE SENSOR SUPPLY CIRCUIT SHORTED TO THE (C918) A/C PRESSURE SENSOR GROUND CIRCUIT
(C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO THE (C918) A/C PRESSURE SENSOR GROUND CIRCUIT
(C818) A/C PRESSURE SENSOR SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE
(C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE
A/C PRESSURE TRANSDUCER
TOTALLY INTEGRATED POWER MODULE (TIPM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1. ACTIVE DTC



NOTE: Diagnose and repair any CAN bus, communication or implausible signal DTCs before proceeding with this test.

NOTE: Diagnose and repair any system voltage or sensor supply voltage DTCs before continuing with this test.

NOTE: Make sure the A/C refrigerant System is properly charged in accordance with the Service Information. (Refer to 24 - Heating and Air Conditioning - Specifications) .
1. Start the engine and allow it to reach normal operating temperature.

WARNING:

When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose clothing. Failure to follow these instructions can result in possible serious or fatal injury.

2. With the scan tool, select View DTCs.


Is the DTC Active at this time?

Yes


No


2. (C818) A/C PRESSURE SENSOR SUPPLY CIRCUIT VOLTAGE
1. Turn the ignition off.
2. Disconnect the A/C Pressure Transducer harness connector.
3. Turn the ignition on.
4. Measure the voltage of the (C818) A/C Pressure Sensor Supply circuit in the A/C Pressure Transducer harness connector.


Is the voltage above 4.5 Volts?

Yes


No


3. (C818) A/C PRESSURE SENSOR SUPPLY CIRCUIT SHORTED TO GROUND
1. Turn the ignition on.
2. Disconnect the Totally Integrated Power Module (TIPM) harness connector.
3. Measure the resistance between ground and the (C818) A/C Pressure Sensor Supply circuit in the A/C Pressure Transducer harness connector.


Is the resistance above 1000 Ohms?

Yes


No


4. (C818) A/C PRESSURE SENSOR SUPPLY CIRCUIT SHORTED TO (C918) A/C PRESSURE SENSOR GROUND CIRCUIT
1. Measure the resistance between the (C818) A/C Pressure Sensor Supply circuit and the (C918) A/C Pressure Sensor Ground circuit in the A/C Pressure Transducer harness connector.


Is the resistance above 100 Ohms?

Yes


No


5. (C818) A/C PRESSURE SENSOR SUPPLY CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (C818) A/C Pressure Sensor Supply circuit between the A/C Pressure Transducer harness connector and the Totally Integrated Power Module (TIPM) harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


6. (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Disconnect the Totally Integrated Power Module (TIPM) harness connector.
3. Measure the resistance between ground and the (C18) A/C Pressure Sensor Signal circuit in the A/C Pressure Transducer harness connector.


Is the resistance above 100 Ohms?

Yes


No


7. (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT SHORTED TO THE (C918) A/C PRESSURE SENSOR GROUND CIRCUIT
1. Measure the resistance between the (C18) A/C Pressure Sensor Signal circuit and the (C918) A/C Pressure Sensor Ground circuit in the A/C Pressure Transducer harness connector.


Is the resistance above 100 Ohms?

Yes


No


8. (C18) A/C PRESSURE SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the (C18) A/C Pressure Sensor Signal circuit between the A/C Pressure Transducer harness connector and the Totally Integrated Power Module (TIPM) harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


9. AC PRESSURE TRANSDUCER
1. Turn the ignition off.
2. Connect the Totally Integrated Power Module (TIPM) harness connector.
3. Connect a jumper wire between the (C818) A/C Pressure Sensor Supply circuit and the (C18) A/C Pressure Sensor Signal circuit in the A/C Pressure Transducer harness connector.
4. Turn the ignition on.
5. With the scan tool, read the AC Pressure Transducer signal voltage.


Is the voltage above 4.5 Volts with the jumper wire in place?

Yes


No


10. TOTALLY INTEGRATED POWER MODULE (TIPM)

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the A/C Pressure Transducer and the Totally Integrated Power Module (TIPM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.


Were any problems found?

Yes


No