P0532 A/C SENDING UNIT VOLTS TOO LOW

When Monitored and Set Condition:

When Monitored: With the ignition on and battery voltage greater than 10.4 volts.
Set Condition: The circuit voltage to the ECM falls below a calibrated threshold for a certain period of time.

POSSIBLE CAUSES

• OTHER DTC'S
• A/C PRESSURE SENSOR
• (C18) SIGNAL CIRCUIT SHORTED TO (K55) RETURN CIRCUIT
• (K72E) 5-VOLT SUPPLY CIRCUIT SHORTED TO (K55) RETURN CIRCUIT
• (C18) SIGNAL CIRCUIT OPEN FROM ECM HARNESS CONNECTOR TO A/C HARNESS
• CONNECTOR
• (K72E) 5-VOLT SUPPLY CIRCUIT OPEN FROM ECM HARNESS TO A/C HARNESS
• CONNECTORS
• (C18) SIGNAL CIRCUIT SHORTED TO GROUND
• (K72E) 5-VOLT SUPPLY CIRCUIT SHORTED TO GROUND
• ECM
• INTERMITTENT CONDITION

DIAGNOSTIC PROCEDURE

1. Turn the ignition on. With the DRBIII®, read DTCs. Are other DTCs present?
   Yes --> Repair other DTCs first. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 2
2. Disconnect the A/C pressure sending unit harness connector. Check connectors - Clean/repair as necessary. Measure the voltage between the (K72E) 5-volt supply and (K55) return circuits of the sensor harness connector. Is the voltage between 4.5 and 5.5 volts?
   Yes --> Go To 3
   No --> Go To 4
3. While monitoring DRBIII®, use a jumper wire to connect the (K72E) 5-volt supply circuit to the (C18) signal circuit at the sensor harness connector. Did P0533 set?
   Yes --> Replace the A/C pressure sensor. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
   No --> Go To 4
4. Turn the ignition off. Disconnect the ECM harness connectors. Measure the resistance between the (C18) signal circuit and (K55) return circuit in the sensor harness connector. Is the resistance greater than 100k Ohms?
   Yes --> Go To 5
   No --> Repair the (C18) signal circuit shorted to the (K55) return circuit. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
5. Measure the resistance between the (K72E) 5-volt supply circuit and (K55) return circuit in the sensor harness connector. Is the resistance greater than 100k Ohms?
   Yes --> Go To 6
   No --> Repair the (K72E) 5-volt supply circuit shorted to the (K55) return circuit. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
6. Measure the resistance of the (C18) signal circuit between the sensor harness connector and the ECM harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 7
   No --> Repair the open (C18) signal circuit. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
7. Measure the resistance of the (K72E) 5-volt supply circuit between the sensor harness connector and the ECM harness connector. Is the resistance less than 10 Ohms?
   Yes --> Go To 8
   No --> Repair the open (K72E) 5-volt supply circuit. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
8. Measure the resistance between the (C18) signal circuit in the sensor harness connector and battery negative. Is the resistance greater than 100k Ohms?
   Yes --> Go To 9
   No --> Repair the (C18) signal circuit shorted to ground. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
9. Measure the resistance between the (K72E) 5-volt supply circuit in the sensor harness connector and battery negative. Is the resistance greater than 100k Ohms?
   Yes --> Go To 10
   No --> Repair the (K72E) 5-volt supply circuit shorted to ground. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).
10. Reconnect the ECM harness connectors. Turn the ignition on. While monitoring DRBIII®, use a jumper wire to connect the (K72E) 5-volt supply circuit with the (C18) signal circuit at the sensor harness connector. Did DTC P0533 set?
    Yes --> Test Complete.
    No --> Replace the ECM. Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIESEL).