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DTC P0532: A/C Pressure Sensor Circuit Low Input
 
 
 
 
CIRCUIT OPERATION
  • A power voltage of 5 V is applied to the A/C pressure sensor connector power terminal from the ECM connector terminal ACP5&BVS5 and grounded to the ECM connector terminal ACPE&BVSE from the A/C pressure sensor connector ground terminal.
  • The sensor signal is inputted to the ECM connector terminal AC/P from the A/C pressure sensor connector output terminal.
 
 
TECHNICAL DESCRIPTION
  • The A/C pressure sensor detects a change in A/C refrigerant pressure and inputs the signal to the ECM.
 
 
DTC SET CONDITIONS
Check Conditions
  • After 2 seconds since the ignition switch is turned ON or since the completion of engine start.
  • Battery positive voltage is more than 10 V and is less than 16.5 V.
Judgment Criterion
  • Sensor output voltage is 0.2 V or less for 4 seconds.
 
 
FAIL-SAFE AND BACKUP FUNCTION
  • Control as if the A/C refrigerant is 0.063 MPa.
 
 
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
  • Failed A/C pressure sensor
  • Open/short circuit or harness damage in A/C pressure sensor circuit or loose connector contact
  • Failed ECM
 
 
 
DIAGNOSIS
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
  • MB991348: Test Harness
STEP 1. Using scan tool (M.U.T.-III), check data list.
cautionTo prevent damage to scan tool (M.U.T.-III), always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool (M.U.T.-III).
(1) Connect scan tool (M.U.T.-III). Refer to HOW TO CONNECT THE SCAN TOOL (M.U.T.-III) .
(2) Turn the ignition switch to the "ON" position.
(3) Check the following items in the data list. Refer to Data List Reference Table .
  1. Item 172: A/C Pressure Sensor (Voltage)
  2. Item 175: A/C Pressure Sensor
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Go to Step 2.
 
STEP 2. Measure the sensor supply voltage at A/C pressure sensor harness side connector.
(1) Disconnect the connector and measure at the harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal ACP5&BVS5 line and ground.
  • Voltage should be between 4.9 and 5.1 volts.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage between 4.9 and 5.1 volts?
Go to Step 6.
Go to Step 3.
 
STEP 3. Measure the power supply voltage at ECM connector.
(1) Disconnect connector, and measure at harness side.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal ACP5&BVS5 and ground.
  • Voltage should be between 4.9 and 5.1 volts.
Is the measured voltage between 4.9 and 5.1 volts?
Repair or replace the connector(s), or check and repair the harness of open circuit in ACP5&BVS5 line between A/C pressure sensor connector and ECM connector. Then go to Step 10.
Go to Step 4.
 
STEP 4. Check of short to ground in ACP5&BVS5 line between A/C pressure sensor connector and ECM connector.
Is the harness wire in good condition?
Go to Step 5.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 5. Using scan tool (M.U.T.-III), check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to Data List Reference Table .
  1. Item 172: A/C Pressure Sensor (Voltage)
  2. Item 175: A/C Pressure Sensor
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
It can be assumed that this malfunction is intermittent. Refer to GROUP 00, How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions .
Replace the ECM. Then go to Step 10.
 
STEP 6. Measure the sensor supply voltage at A/C pressure sensor harness side connector.
(1) Use special tool test harness (MB991348) to connect connector, and measure at pick-up harness.
(2) Turn the ignition switch to the "ON" position.
(3) Measure the voltage between terminal ACP5&BVS5 line and ground.
  • Voltage should be between 4.9 and 5.1 volts.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage between 4.9 and 5.1 volts?
Go to Step 7.
Repair or replace the connector(s), or check and repair the harness of damage in ACP5&BVS5 line between A/C pressure sensor connector and ECM connector. Then go to Step 10.
 
STEP 7. Measure the sensor output voltage at A/C pressure sensor harness side connector.
(1) Use special tool test harness (MB991348) to connect connector, and measure at pick-up harness.
(2) Start the engine.
(3) Measure the voltage between terminal AC/P line and ground.
(4) Perform the simple inspection for the A/C pressure sensor (Refer to GROUP 55A - On-vehicle Service - Simple Inspection of A/C Pressure Sensor ).
  • Relationship between the manometer indication and the output voltage should comply with the graph.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage normal?
Go to Step 9.
Go to Step 8.
 
STEP 8. Check of short to ground AC/P line between A/C pressure sensor connector and ECM connector.
Is the harness connector in good condition?
Replace the A/C pressure sensor. Then go to Step 10.
Repair the connector(s) or wiring harness. Then go to Step 10.
 
STEP 9. Measure the sensor output voltage at ECM connector by backprobing.
(1) Do not disconnect the connector.
(2) Start the engine.
(3) Measure the voltage between terminal AC/P line and ground by backprobing.
(4) Perform the simple inspection for the A/C pressure sensor (Refer to GROUP 55A - On-vehicle Service - Simple Inspection of A/C Pressure Sensor ).
  • Relationship between the manometer indication and the output voltage should comply with the graph.
(5) Turn the ignition switch to the "LOCK" (OFF) position.
Is the measured voltage normal?
Go to Step 5.
Repair or replace the connector(s), or check and repair the harness of open circuit, and damage in AC/P line between A/C pressure sensor connector and ECM connector. Then go to Step 10.
 
STEP 10. Using scan tool (M.U.T.-III), check data list.
(1) Turn the ignition switch to the "ON" position.
(2) Check the following items in the data list. Refer to Data List Reference Table .
  1. Item 172: A/C Pressure Sensor (Voltage)
  2. Item 175: A/C Pressure Sensor
(3) Turn the ignition switch to the "LOCK" (OFF) position.
Is the sensor operating properly?
The inspection is complete.
Retry the troubleshooting.