Signal Too High. Permanent Fault
Signal too high. Permanent fault
EFI-123 Engine coolant temperature (ECT) sensor signal
Checking ground lead
Warning! Before fault-tracing, disconnect engine cooling fan (FC) relay connector A so that the engine cooling fan (FC) will not run. The diagnostic trouble code (DTC) EFI-514 Engine cooling fan (FC) low-speed, signal may be stored. After fault-tracing the connector must be re-connected.
- Ignition off.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Disconnect temperature sensor.
- Connect an ohmmeter between temperature sensor connector terminal 2 (engine control module (ECM) side) and ground.
Note! If the engine cooling fan runs on, it must be allowed to stop before taking resistance readings.
The ohmmeter should read approximately 0 ohms.
OK - Checking the signal cable
Not OK - Checking control module connector
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Checking the signal cable
- Ignition on.
- Temperature sensor disconnected.
- Connect a voltmeter between temperature sensor connector terminals 1 and 2 (engine control module (ECM) side).
The voltmeter should read approximately 5 V.
OK - Checking temperature sensor resistance
Low - Checking control module connector
High - Checking for a short-circuit
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Checking for a short-circuit
- Check cable between engine coolant temperature (ECT) sensor terminal 1 and engine control module (ECM) #A31 for a short-circuit to supply voltage according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Checking engine coolant temperature (ECT) sensor
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Checking control module connector
- Ignition off.
- Temperature 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 temperature sensor connector terminal 2 (engine control module (ECM) side) and ground.
The ohmmeter should read approximately 0 ohms.
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 temperature sensor terminal 2 and engine control module (ECM) #A18 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 temperature sensor resistance
- Ignition off.
- Temperature sensor disconnected.
Connect an ohmmeter between temperature sensor connector terminals 1 and 2 (temperature sensor side).
The ohmmeter should read approximately 2200 ohms at +25°C (see diagram).
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 engine coolant temperature (ECT) 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.
Continue - Verification
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Replacing component
- Try a new engine coolant temperature (ECT) sensor.
Continue - Verification
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Checking engine coolant temperature (ECT) sensor
Hint: The engine coolant temperature (ECT) sensor may fail if there has been a short-circuit to voltage supply in the signal cable. Check the temperature sensor as follows:
- Ignition off.
- Temperature sensor disconnected.
- Connect an ohmmeter between temperature sensor connector terminals 1 and 2 (temperature sensor side).
The ohmmeter should read approximately 2200 ohms at +25°C (see diagram).
OK - Fault-tracing information
Not OK - Replacing component
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Fault-tracing information
Temperature sensor is OK.
Continue - Verification
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Replacing component
- Try a new engine coolant temperature (ECT) sensor.
Continue - Verification
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Checking control module connector
- Ignition off.
- Temperature 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.
- Ignition on.
- Connect a voltmeter between temperature sensor connector terminals 1 and 2 (engine control module (ECM) side).
The voltmeter should read approximately 5 V.
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 temperature sensor terminal 1 and engine control module (ECM) #A31 for an open-circuit according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
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, reinstall components etc.
- Start engine and run to normal operating temperature. The engine should be hot enough for the thermostat to open.
- Select the Volvo Scan Tool (ST) symbol to read off engine coolant temperature (ECT).
Is the engine coolant temperature (ECT) value within its permitted range.
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 ground lead
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