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Home >> Volvo >> 1998 >> C70 Convertible L5-2.4L Turbo VIN 56 B5254T >> Repair and Diagnosis >> A L L Diagnostic Trouble Codes ( DTC ) >> Testing and Inspection >> Manufacturer Code Charts >> EFI Codes (Engine Control System) >> EFI-131 >> Engine Speed (RPM) Sensor; Permanent Fault, Signal Missing >> Signal Missing. Permanent Fault

Signal Missing. Permanent Fault






Signal missing. Permanent fault

EFI-131 Engine speed (RPM) sensor, signal missing

Checking engine speed (RPM) sensor resistance








- Ignition off.
- Disconnect the engine speed (RPM) sensor.
Connect a voltmeter between engine speed (RPM) sensor connector terminals 1 and 2 (engine control module (ECM) side).









The ohmmeter should read 200 - 500 ohms depending on engine speed (RPM) sensor temperature.

OK - Checking ground lead

Not OK - Try a new engine speed (RPM) sensor. Then continue with Verification.
Replacing component

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Replacing component
- Try a new engine speed (RPM) sensor.





Continue - Verification

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Checking ground lead








- Ignition off.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Engine speed (RPM) sensor disconnected.
Connect an ohmmeter between engine speed (RPM) sensor connector terminal 2 (engine control module (ECM) side) and ground.









The ohmmeter should read approximately 0 ohms.

OK - Checking signal cable resistance to ground

Not OK - Checking engine control module (ECM) ground terminals

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Checking engine control module (ECM) ground terminals












- Ignition off.
- Engine speed (RPM) sensor disconnected.
- Check engine control module (ECM) connector and ground terminals 31/32 and 31/33 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 engine speed (RPM) sensor connector terminal 2 (engine control module (ECM) side) and ground.









The ohmmeter should read approximately 0 ohms.

OK - Checking signal cable resistance to ground

Not OK - Check cable between engine speed (RPM) sensor connector 2 and engine control module (ECM) #A6 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Then continue with Verification
Checking for an open-circuit

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Checking for an open-circuit








- Check cable between engine speed (RPM) sensor connector 2 and engine control module (ECM) #A6 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 signal cable resistance to ground








- Ignition off.
- Engine speed (RPM) sensor disconnected.
Connect an ohmmeter between engine speed (RPM) sensor connector terminals 1 and 2 (engine control module (ECM) side).









The ohmmeter should read 15 - 25 kohms.

OK - Checking for a short-circuit to supply voltage in signal cable

Low - Check cable between engine speed (RPM) sensor terminal 1 and control module #A20 for a short-circuit to ground according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Then continue with Verification.
Checking for a short-circuit

High - Checking control module connector

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Checking for a short-circuit








- Check cable between engine speed (RPM) sensor terminal 1 and control module #A20 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.
- Engine speed (RPM) 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 engine speed (RPM) sensor connector terminals 1 and 2 (engine control module (ECM) side).









The ohmmeter should read 15 - 25 kohms.

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

Not OK - Check cable between engine speed (RPM) sensor terminal 1 and engine control module (ECM) #A20 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Then continue with Verification.
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 - FAULT FOUND

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Checking for an open-circuit








- Check cable between engine speed (RPM) sensor terminal 1 and engine control module (ECM) #A20 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 for a short-circuit to supply voltage in signal cable








- Ignition on.
- Engine speed (RPM) sensor disconnected.
Connect a voltmeter between engine speed (RPM) sensor connector terminal 1 and 2 (control module side).









The voltmeter should read 1 - 2 V.

OK - Checking the engine control module (ECM) connector

Not OK - Check cable between engine speed (RPM) sensor terminal 1 and engine control module (ECM) #A20 for a short-circuit to supply voltage according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Then continue with Verification.
Checking for a short-circuit

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Checking for a short-circuit




- Check cable between engine speed (RPM) sensor terminal 1 and engine control module (ECM) #A20 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 the engine control module (ECM) connector




- Ignition off.
- Check engine speed (RPM) sensor connector for contact resistance and oxidation and remedy according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
- Try to start the engine.

Does the engine start?

Yes - The engine did not start because of loose connections in the engine speed (RPM) sensor and/or engine control module (ECM) connectors. Check connectors for contact resistance and oxidation and remedy in accordance with Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault. Then continue with Verification.
Checking for contact resistance and oxidation

No - Check carrier plate/flywheel for damage and scratches through the engine speed (RPM) sensor hole. If no faults are detected on the carrier plate/flywheel: Try a new engine speed (RPM) sensor. Then continue with Verification.
Checking for damage

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Checking for contact resistance and oxidation
The engine did not start because of loose connections in the engine speed (RPM) sensor and/or engine control module (ECM) connectors.
- Check connectors for contact resistance and oxidation and remedy in accordance with Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.





Continue - Verification

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Checking for damage
- Check carrier plate/flywheel for damage and scratches through the engine speed (RPM) sensor hole. If no faults are detected on the carrier plate/flywheel: Try a new engine speed (RPM) sensor.

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.
- Reconnect connectors and reinstall components.
- Try to start the engine.

Does the engine start?

Yes - VERIFIED

No - 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 engine speed (RPM) sensor resistance

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