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Home >> Volvo >> 1996 >> 850 GLT L5-2.4L VIN 55 B5254S >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> Manufacturer Code Charts >> EFI / DTC Codes (Engine Control System) >> Motronic 4.4 (MFI) >> DTC EFI-621 >> Signal Too High. Permanent Fault

Signal Too High. Permanent Fault





Checking Ground Lead
- Ignition off.
- Wait for approx. 150 seconds (cars with immobilizer 245 seconds).
- Disconnect tank pressure sensor.
- Connect an ohmmeter between fuel tank pressure sensor connector terminal 2 (engine control module (ECM) side) and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ Proceed to Checking Signal Cable section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Connector 24/4
- Ignition off.
- Tank pressure sensor disconnected.
- Check connector 24/4 for contact resistance, oxidation and remedy.
- Assemble connector 24/4.
- Connect an ohmmeter between fuel tank pressure sensor connector terminal 2 (engine control module side) and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ The diagnostic trouble code (DTC) has been caused by loose connections in connector 24/4.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Ground Lead 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 E6 (engine control module side) and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ Check cable between fuel tank pressure sensor terminal 2 and connector 24/4 terminal C6 for an open-circuit.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Connector 24/2
- Ignition off
- Tank pressure sensor disconnected
- Connector 24/4 disassembled.
- Check connector 24/2 for contact resistance or oxidation and remedy.
- Assemble connector 24/2.
- Connect an ohmmeter between connector 24/4 terminal E6 (engine control module side) and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ The diagnostic trouble code has been caused by loose connections in connector 24/2.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Ground Lead Between Connectors 24/2 and 24/4
- Ignition off
- Tank pressure sensor disconnected
- Assemble connector 24/4.
- Disconnect connector 24/2.
- Connect an ohmmeter between connector 24/4 terminal C7 (engine control module side) and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ Check cable between connector 24/2 terminal C7 and connector 24/4 terminal C6 for an open-circuit.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking The Engine Control Module Connector
- Ignition off
- Tank pressure sensor disconnected
- Connector 24/2 disassembled.
- Check engine control module connector for contact resistance or oxidation and remedy.
- Engine control module connected.
- Connect an ohmmeter between connector 24/2 terminal C7 (engine control module side) and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ The diagnostic trouble code was caused by loose connections in the engine control module connector.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking For An Open-circuit
- Check cable between connector 24/2 terminal C7 and engine control module for an open-circuit.

^ Then proceed to Verification section below.





Checking Signal Cable
- Ignition on.
- Tank pressure sensor disconnected
- Connect a voltmeter between fuel tank pressure sensor connector terminal 3 and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ Proceed to Checking Fuel Tank Pressure Sensor section below.

If value is lower:
^ Proceed to Checking Connector 24/4 section below.

If value is higher:
^ Proceed to test step below.





Checking Signal Cable Between Connector 24/4 And Fuel Tank Pressure Sensor
- Ignition on.
- Tank pressure sensor disconnected.
- Disconnect connector 24/4.
- Connect a voltmeter between connector 24/4 terminal E5 and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ Check cable between fuel tank pressure sensor terminal 3 and connector 24/4 terminal E5 for a short-circuit to supply voltage.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Signal Cable Between Connector 24/4 And 24/2
- Ignition on.
- Tank pressure sensor disconnected.
- Assemble connector 24/4.
- Disconnect connector 24/2.
- Connect a voltmeter between connector 24/2 terminal C6 and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ Check cable between connector 24/2 terminal C7 and connector 24/4 terminal E5 for a short-circuit to supply voltage.
^ Then proceed to Verification section below.

If reading is Incorrect:
^ Check cable between connector 24/2 terminal C7 and engine control module # B3 for a short-circuit to supply voltage.
^ Then proceed to Verification section below.





Checking Connector 24/4
- Ignition off.
- Tank pressure sensor disconnected.
- Check connector 24/4 for contact resistance or oxidation and remedy.
- Assemble connector 24/4.
- Ignition on.
- Connect a voltmeter between fuel tank pressure sensor connector terminal 3 and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ The diagnostic trouble code has been caused by loose connections in connector 24/4.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Signal Cable Between Connector 24/4 And Fuel Tank Pressure Sensor
- Ignition off.
- Tank pressure sensor disconnected.
- Disconnect connector 24/4.
- Connect a voltmeter between connector 24/4 terminal E5 (engine control module (ECM) side) and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ Check cable between fuel tank pressure sensor terminal 3 and connector 24/4 terminal E5 for an open-circuit.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Connector 24/2
- Ignition off
- Tank pressure sensor disconnected
- Connector 24/4 disassembled.
- Check connector 24/2 for contact resistance or oxidation and remedy.
- Assemble connector 24/2.
- Ignition on.
- Connect a voltmeter between connector 24/4 terminal E5 and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ The diagnostic trouble code has been caused by loose connections in connector 24/2.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking Signal Cable Between Connector 24/4 and 24/2
- Ignition on.
- Tank pressure sensor disconnected
- Assemble connector 24/4.
- Disconnect connector 24/2.
- Connect a voltmeter between connector 24/2 terminal C6 (engine control module side) and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ Check cable between connector 24/2 terminal C6 and connector 24/4 terminal E5 for an open-circuit.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Proceed to test step below.





Checking The Engine Control Module Connector
- Ignition off
- Tank pressure sensor disconnected
- Connector 24/2 disassembled.
- Check engine control module (ECM) connector for contact resistance or oxidation and remedy.
- Engine control module (ECM) connected.
- Ignition on.
- Connect a voltmeter between connector 24/2 terminal C6 and ground.
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ The diagnostic trouble code was caused by loose connections in the engine control module connector.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Check cable between connector 24/2 terminal C6 and engine control module #B31 for an open-circuit.
^ Then proceed to Verification section below.





Checking Fuel Tank Pressure Sensor
- Ignition off
- Connect fuel tank pressure sensor.
- Start the engine and idle it for a few minutes.
- Read diagnostic trouble code status message.
- The voltmeter should read approx. 5 Volts.

If Status Message displays a Permanent Fault:
^ Try a new tank pressure sensor.
^ Then proceed to Verification section below.

If Status Message displays an Intermittent Fault:
^ The diagnostic trouble code has been caused by loose connections in the fuel tank pressure sensor connector. Check connector for contact resistance or oxidation and remedy.
^ Then proceed to Verification section below.





Verification
- After carrying out the repair, check that the fault has been remedied as follows.
- Ignition off
- Ensure that fuel tank pressure sensor, A/C pressure sensor, accelerometer and engine control module are connected.
- Connectors 24/2 and 24/4 connected.
- Ignition on.
- Erase diagnostic trouble code.
- Start the engine and idle it.
- Does the diagnostic trouble code recur?

No:
^ Fault corrected.

Yes:
^ Proceed to test step below.

Fault-tracing Information
- The verification result shows that the fault persists.
- Do you want to exit fault-tracing?

Yes:
^ Fault not corrected

No:
^ Return to Checking Ground Lead section above.
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