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Home >> Volvo >> 1998 >> V70 GL 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) >> DTC EFI-123 >> Signal Too High. Permanent Fault

Signal Too High. Permanent Fault





Checking Ground Lead

WARNING: Before fault-tracing disconnect engine cooling fan (FC) relay connector A so that the engine cooling fan will not run. Diagnostic trouble code (DTC) EFI-514 Engine cooling fan low-speed, signal may be stored. After fault-tracing reconnect connector.

- Ignition off.
- Wait approx. 150 seconds.
- Disconnect temperature sensor.
- Connect an ohmmeter between engine coolant temperature (ECT) sensor connector terminal 2 (engine control module (ECM) side) and ground.

NOTE: If the engine cooling fan continues operating after engine has been switched off, it must be allowed to stop before resistance measurements are taken.

- The ohmmeter should read approx. 0 ohms.

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

If reading is incorrect:
^ Proceed to Checking The Engine Control Module Connector section below.





Checking Signal Cable
- Ignition on.
- Engine coolant temperature sensor disconnected.
- Connect a voltmeter between engine coolant temperature sensor connectors terminal 1 and 2 (engine control module (ECM side).
- The voltmeter should read approx. 5 Volts.

If reading is OK:
^ Proceed to Checking The Engine Coolant Temperature Sensor Resistance section below.

If value is lower:
^ Proceed to Checking The Engine Control Module Connector

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





Checking For A Short-circuit
- Check cable between the engine coolant temperature sensor terminal 1 and engine control module # A31 for a short-circuit to supply voltage.

Then continue with:
^ ^ Proceed to Checking The Engine Coolant Temperature Sensor section below.





Checking The Engine Control Module Connector
- Ignition off.
- Engine coolant temperature sensor disconnected.
- Check engine control module connector for contact resistance and oxidation and remedy according.
- Engine control module connected.
- Connect an ohmmeter between engine coolant temperature 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 was caused by poor contact in the engine control module connector.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Check cable between the engine coolant temperature sensor connector terminal 2 and engine control module # A18 for an open-circuit.
^ Then proceed to Verification section below.





Checking The Engine Coolant Temperature Sensor Resistance
- Ignition off.
- Engine coolant temperature sensor disconnected.
- Connect an ohmmeter between engine coolant temperature sensor connectors terminals 1 and 2 (engine coolant temperature sensor side).
- The ohmmeter should read approx. 2,200 ohms at +25°C (see graph within image).

If reading is OK:
^ The diagnostic trouble code has been caused by poor contact in the engine coolant temperature sensor connector. Check connector for contact resistance and oxidation and remedy.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Try a new engine coolant temperature sensor.
^ Then proceed to Verification section below.





Checking The Engine Coolant Temperature Sensor
- The engine coolant temperature sensor may malfunction if there is short-circuit to voltage supply of the signal cable. Check the engine coolant temperature sensor as follows.
- Ignition off.
- Engine coolant temperature sensor disconnected.
- Connect an ohmmeter between engine coolant temperature sensor connector terminals 1 and 2 (engine coolant temperature sensor side).
- The ohmmeter should read approx. 2,200 ohms at +25°C (see graph within image).

If reading is OK:
^ Engine coolant temperature sensor is OK.
^ Then proceed to Verification section below.

If reading is incorrect:
^ Try a new engine coolant temperature sensor.
^ Then proceed to Verification section below.





Checking The Engine Control Module Connector
- Ignition off.
- Engine coolant temperature sensor disconnected.
- Check engine control module connector for contact resistance and oxidation and remedy.
- Engine control module connected.
- Ignition on.
- Connect a voltmeter between engine coolant temperature sensor connector terminals 1 and 2 (engine control module side).
- The voltmeter should read approx. 5 Volts.

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

If reading is incorrect:
^ Check cable between the engine coolant temperature sensor terminal 1 and engine control module # A31 for an open-circuit.
^ Then proceed to Verification section below.





Verification
- After carrying out the repair, check that the fault has been
remedied as follows.
- Ignition off.
- Reconnect connectors, reinstall components etc. Connect a multimeter 999 6525 with temperature box 999 5281 and temperature sensor 999 5282
- Carefully remove the expansion tank cap.

WARNING: THE COOLANT MAY BE 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 working temperature. The engine should be warm enough for the thermostat to open.
- Go into scrolling value list.
- Read engine coolant temperature.
- Is the engine coolant temperature value within bounds.

If reading is OK:
^ Fault corrected.

If reading is incorrect:
^ 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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