Faulty Signal. Permanent Fault
Faulty signal. Permanent fault
EFI-123 Engine coolant temperature (ECT) sensor, signal
Checking engine coolant temperature (ECT) sensor signal
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.
- Connect multimeter 999 6525 MULTIMETER 999 6525 Multimeter with temperature box 999 5281 TEMPERATURE SENSOR 999 5281 Temperature Sensor and temperature sensor 999 5282 TEMPERATURE SENSOR 2.5 M 999 5282 Temperature Sensor 2.5 M.
- Carefully remove the expansion tank cover.
Warning! Danger - coolant is hot.
- Clamp the hose between the radiator and thermostat housing using a hose clip and disconnect the hose from the thermostat housing.
- Insert sensor in thermostat housing and reinstall hose.
- Remove hose clip.
- Start engine and run up to operating temperature. The engine should be hot enough for the thermostat to open.
- Select Volvo Scan Tool (ST) to read off the engine coolant temperature (ECT).
Check that the engine coolant temperature (ECT) is within its permitted range.
Is the temperature within its permitted range?
Yes - Replacing component
No - Checking engine coolant temperature (ECT) sensor
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Replacing component
- Try a new coolant thermostat.
Continue - Verification
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Checking engine coolant temperature (ECT) sensor
- Ignition on.
- Disconnect temperature sensor.
Select Volvo Scan Tool (ST) to read off the voltage across the engine coolant temperature (ECT) sensor.
The reading should be approximately 5 V.
OK - Checking ground lead
Not OK - Checking control module connector
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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.
Select Volvo Scan Tool (ST) to read off the voltage across the engine coolant temperature (ECT) sensor.
The reading should be approximately 5 V.
OK - Fault-tracing information
Not OK - Checking for a short-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 a short-circuit
- Check cable between engine coolant temperature (ECT) sensor terminal 1 and engine control module (ECM) #A31 for a short-circuit to another cable according to Checking wiring and terminals. Permanent fault Checking Wiring and Terminals. Permanent Fault.
Continue - Verification
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Checking ground lead
- Ignition off.
- Wait for approximately 150 seconds (cars with immobilizer 245 seconds).
- Temperature sensor disconnected.
Connect an ohmmeter between temperature sensor connector terminal 2 (engine control module (ECM) side) and ground.
The ohmmeter should read approximately 0 ohms.
OK - Replacing component
Not OK - Checking control module connector
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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.
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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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 engine coolant temperature (ECT) sensor signal
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