Signal Too Low: Permanent Fault

Signal too low: Permanent fault

EFI-225 Air conditioning (A/C) pressure sensor, signal

Checking power cable








- Ignition off.
- Disconnect the air conditioning (A/C) pressure sensor.
- Ignition on.








- Connect a voltmeter between air conditioning (A/C) pressure sensor connector 3 and ground.

The voltmeter should read 5 V.

OK - Checking signal cable resistance

Low - Checking power cable resistance to ground

High - Checking for a short-circuit

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Checking for a short-circuit
The air conditioning (A/C) pressure sensor power cable is connected inside the engine control module (ECM) to the fuel tank pressure sensor, atmospheric pressure sensor and accelerometer power cables. If anything happens to any of these cables all four will be affected.
Check cables between:
- Accelerometer terminal 1 and engine control module (ECM) #B1.
- Air conditioning (A/C) pressure sensor terminal 3 and engine control module (ECM) #B29.
- atmospheric pressure sensor terminal 1 and engine control module (ECM) #B29
- tank pressure sensor terminal 1 and engine control module (ECM) #B15.
- for a short-circuit to supply voltage according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.





Continue - Verification

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Checking signal cable resistance








- Ignition off.
- Air conditioning (A/C) pressure sensor disconnected.








- Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 2 and ground.

The ohmmeter should read approximately 10 kohms.

OK - Checking the air conditioning (A/C) pressure sensor

Not OK - Checking for contact resistance and oxidation

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Checking the air conditioning (A/C) pressure sensor








- Ignition off.
- Connect air conditioning (A/C) pressure sensor.
- Start the engine and idle it.
- Air conditioning (A/C) switch on.
- Blower fan on.








- Select Volvo Scan Tool (ST) to read off the value of the air conditioning (A/C) pressure sensor signal.

Voltage should increase when the air conditioning (A/C) compressor starts.

OK - Checking for contact resistance and oxidation

Not OK - Replacing component

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Checking for contact resistance and oxidation
The cause of the diagnostic trouble code (DTC) has been loose connections in the air conditioning (A/C) pressure sensor connector.
- Check connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Select "Continue" when the fault has been repaired.

Continue - Verification

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Replacing component
- Try a new air conditioning (A/C) pressure sensor.





Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking power cable resistance to ground








- Ignition off.
- Air conditioning (A/C) pressure sensor disconnected.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - No Fault Found

Low - Checking accelerometer

High - Checking control module connector

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Checking accelerometer








- Ignition off.
- Air conditioning (A/C) pressure sensor disconnected.
- Disconnect accelerometer.
Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Replacing component

Not OK - Checking atmospheric pressure sensor

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Replacing component
- Try a new accelerometer.





Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking atmospheric pressure sensor








- Ignition off.
- Air conditioning (A/C) pressure sensor and accelerometer disconnected.
- Disconnect atmospheric pressure sensor.
Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Replacing component

Not OK - Check

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Replacing component
- Try a new atmospheric pressure sensor.





Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking fuel tank pressure sensor








- Ignition off.
- Air conditioning (A/C) pressure sensor, accelerometer and atmospheric pressure sensor disconnected.
- Disconnect fuel tank pressure sensor.
Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Replacing component

Not OK - Checking for a short-circuit

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Replacing component
- Try a new fuel tank pressure sensor.





Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking for a short-circuit
The air conditioning (A/C) pressure sensor power cable is connected inside the engine control module (ECM) to the fuel tank pressure sensor, atmospheric pressure sensor and accelerometer power cables. If anything happens to any of these cables all four will be affected.
Check cables between:
- Accelerometer terminal 1 and engine control module (ECM) #B1.
- Air conditioning (A/C) pressure sensor terminal 3 and engine control module (ECM) #B29.
- atmospheric pressure sensor terminal 1 and engine control module (ECM) #B29
- tank pressure sensor terminal 1 and engine control module (ECM) #B15.
- for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.





Continue - Verification

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Checking control module connector












- Ignition off.
- Air conditioning (A/C) pressure sensor disconnected.
- Check control module connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Control module connected.
Connect an ohmmeter between air conditioning (A/C) pressure sensor connector 3 and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Fault-tracing information

Not OK - Checking for an open-circuit

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Fault-tracing information
- The cause of the diagnostic trouble code (DTC) has been loose connections in the control module connector.

Select "Continue" when the fault has been repaired.

Continue - Verification

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Checking for an open-circuit




- Check cable between air conditioning (A/C) pressure sensor terminal 3 and engine control module (ECM) #B29 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Select "Continue" when the fault has been repaired.

Continue - Verification

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Verification




Verification

Hint: After carrying out the repair, check that the fault has been remedied as follows:












- Ignition off.
- Air conditioning (A/C) pressure sensor and engine control module (ECM) connected.
- Start the engine and idle it.
- Air conditioning (A/C) switch on.
- Blower fan on.
- Wait until the air conditioning (A/C) compressor has started.








- Select Volvo Scan Tool (ST) to read off diagnostic trouble codes (DTCs).

If EFI-225 is stored it should have intermittent status.

OK - VERIFIED

Not OK - VERIFICATION FAILED

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VERIFIED - FAULT FOUND

VERIFICATION FAILED - Fault-tracing information

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Fault-tracing information




Information

Fault-tracing information
The fault should have been detected and remedied. As this is not the case fault-tracing has failed.
Exit fault-tracing for this diagnostic trouble code (DTC) or make another attempt.

Do you want to exit fault-tracing?

Yes - Exit fault-tracing

No - Attempt New Test

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Attempt New Test - Checking power cable

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Checking for contact resistance and oxidation
The cause of the diagnostic trouble code (DTC) has been loose connections in the air conditioning (A/C) pressure sensor connector.
- Check connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Select "Continue" when the fault has been repaired.

Continue - Verification

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Check

Does the car have leak diagnosis?

Yes - Checking fuel tank pressure sensor

No - Checking for a short-circuit

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