Part 1

Signal too low: Permanent fault

EFI-621 Fuel tank pressure sensor, signal

Checking power cable








- Ignition off.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Disconnect tank pressure sensor.
Connect an ohmmeter between fuel tank pressure sensor connector terminal 1 (engine control module (ECM) side) and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Checking the signal cable

Not OK - Checking power cable resistance

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Checking power cable resistance








- Ignition off.
- Tank pressure sensor disconnected.
Connect an ohmmeter between fuel tank pressure sensor connector terminal 1 (engine control module (ECM) side) and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - No Fault Found

Low - Checking connector 24/4

High - Checking power cables

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Checking connector 24/4








- Ignition off.
- Tank pressure sensor disconnected.
- Check connector 24/4 for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Assemble connector 24/4.
Connect an ohmmeter between fuel tank pressure sensor connector terminal 1 (engine control module (ECM) side) and ground.









The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Fault-tracing information

Not OK - Checking power cable between connector 24/4 and fuel tank pressure sensor

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Fault-tracing information
- The diagnostic trouble code (DTC) has been caused by loose connections in connector 24/4.





Continue - Verification

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Checking power cable between connector 24/4 and fuel tank pressure sensor








- Ignition off.
- Tank pressure sensor disconnected.
- Disassemble connector 24/4.
Connect an ohmmeter between connector 24/4 terminal E4 (engine control module (ECM) side) and ground.





The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Checking for a short-circuit

Not OK - Checking connector 24/2

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Checking for a short-circuit








- Check cable between fuel tank pressure sensor terminal 1 and connector E4 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Continue - Verification

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Checking connector 24/2








- Ignition off.
- Tank pressure sensor disconnected.
- Connector 24/4 disassembled.
- Check connector 24/2 for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Assemble connector 24/2.
Connect an ohmmeter between connector 24/4 terminal E4 (engine control module (ECM) side) and ground.





The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Fault-tracing information

Not OK - Checking power cable between connector 24/4 and 24/2

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Fault-tracing information
- The diagnostic trouble code (DTC) has been caused by loose connections in connector 24/2.





Continue - Verification

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Checking power cable between connector 24/4 and 24/2








- Ignition off.
- Disassemble connector 24/2.
Connect an ohmmeter between connector 24/2 terminal C5 (engine control module (ECM) side) and ground.





The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Checking for an open-circuit

Not OK - Checking control module connector

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Checking for an open-circuit




- Check cable between connector 24/2 terminal C5 and connector 24/4 terminal E4 for an open-circuit 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.
- Tank pressure sensor disconnected.
- Connector 24/4 disassembled.
- 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.
- Connect control module.
Connect an ohmmeter between connector 24/2 terminal C5 (engine control module (ECM) side) 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.





Continue - Verification

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Checking for an open-circuit




- Check cable between connector 24/2 terminal C5 and engine control module (ECM) #B15 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.

Continue - Verification

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Checking power cables








- Ignition off.
- Disassemble connector 24/4.
Connect an ohmmeter between connector 24/4 terminal E4 (engine control module (ECM) side) and ground.





The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Checking for a short-circuit

Not OK - Checking cable between 24/2 and 24/4

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Checking for a short-circuit








- Check cable between connector 24/4 terminal E4 and fuel tank pressure sensor terminal 1 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 cable between 24/2 and 24/4








- Ignition off.
- Disassemble connector 24/2.
Connect an ohmmeter between connector 24/2 terminal C5 (engine control module (ECM) side) and ground.





The ohmmeter should read approximately 0.2 - 1.5 kohms.

OK - Checking for a short-circuit

Not OK - Check

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Checking for a short-circuit








- Check cable between connector 24/2 terminal C5 and connector 24/4 terminal E4 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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Fault-tracing information
- Check cable between connector 24/2 terminal C5 and connector 24/4 terminal E4 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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Check

Does the car have air conditioning (A/C)?

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

No - Checking accelerometer

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Checking the air conditioning (A/C) pressure sensor








- Ignition off.
- Assemble connectors 24/2 and 24/4.
- Tank pressure sensor disconnected.
- Disconnect the air conditioning (A/C) pressure sensor.
Connect an ohmmeter between fuel tank pressure sensor connector 1 and ground.









The ohmmeter should read 0.2 - 1.5 kohms.

OK - Replacing component

Not OK - Checking accelerometer

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





Continue - Verification

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Checking accelerometer








- Ignition off.
- Tank pressure sensor disconnected.
- Air conditioning (A/C) pressure sensor disconnected.
- Disconnect accelerometer.
Connect an ohmmeter between fuel tank pressure sensor connector 1 and ground.









The ohmmeter should read 0.2 - 1.5 kohms.

OK - Replacing component

Not OK - Checking atmospheric pressure sensor

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Replacing component
- Try a new accelerometer.





Continue - Verification

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Checking atmospheric pressure sensor








- Ignition off.
- Tank pressure sensor disconnected.
- Air conditioning (A/C) pressure sensor disconnected.
- Accelerometer disconnected.
- Disconnect atmospheric pressure sensor.
Connect an ohmmeter between fuel tank pressure sensor connector 1 and ground.









The ohmmeter should read 0.2 - 1.5 kohms.

OK - Replacing component

Not OK - Checking for a short-circuit

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Replacing component
- Try a new atmospheric pressure sensor.





Continue - Verification

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Checking for a short-circuit
The fuel tank pressure sensor power cable is connected inside the engine control module (ECM) to the accelerometer, atmospheric pressure sensor and air conditioning (A/C) pressure sensor power cables. If anything happens to any of these cables all four will be affected. Air conditioning (A/C) pressure sensor wiring is pre-routed, even on cars without air conditioning, and should always be checked.
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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