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Home >> Volvo >> 1998 >> V70 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Tests W/Codes >> Diagnostic Tests >> DTC P0115/EFI 123, DTC P0116/EFI 123, DTC P0117/EFI 123 & DTC P0118/EFI 123 >> Diagnosis (Signal Faulty)

Diagnosis (Signal Faulty)

WARNING: Before beginning testing, disconnect engine cooling fan relay harness connector "A", to ensure cooling fan will not run. DTC P1619/EFI 514 may be stored. After fault-tracing, harness connector must be reconnected.
NOTE: ECM terminal A18 is a common ground for ECT sensor, Camshaft Position (CMP) sensor, and Throttle Position (TP) sensor.
  1. Connect scan tool. See RETRIEVING & ERASING DTCs  under SELF-DIAGNOSTIC SYSTEM. If no DTC's are stored, go to next step. If DTC P0120/EFI 41, DTC P0122/EFI 41, DTC P0123/EFI 411 or DTC P0340/EFI 314 are stored, check for contact resistance and oxidation at ECM terminal A18. Repair as necessary. After repairs, repeat step.
  2. If signal is PERMANENT, go to next step. If signal is INTERMITTENT, check for loose connections, contact resistance and oxidation at ECT sensor and ECM harness connectors. Repair as necessary. Check for intermittent short to voltage and shorted condition in circuit between ECT sensor harness connector terminal No. 1 and ECM terminal A31. Repair as necessary. Check for intermittent open in circuit between ECT sensor harness connector terminal No. 2 and ECM terminal A18. Repair as necessary. After repairs, go to step  8.
    3. NOTE: Use of external infrared thermometer can be used to monitor engine coolant temperature in place of Volvo temperature box (999 5281) and Volvo temperature sensor (999 5282).
  3. Turn ignition off. Connect DVOM with Volvo temperature box (999 5281) and Volvo temperature sensor (999 5282). Carefully remove expansion tank cap. Clamp hose between radiator and thermostat. Loosen hose clamp, and disconnect hose from thermostat housing. Insert sensor in thermostat housing and reinstall hose. Remove hose clamp. Start engine and warm until thermostat is open. Using scan tool in DIAGNOSTIC MODE, read ECT sensor parameter. If ECT sensor is within specification, replace coolant thermostat. After repairs, go to step  8. If reading is not within specification, go to next step.
  4. Disconnect ECT sensor harness connector. Turn ignition on. Using scan tool in DIAGNOSTIC MODE, scroll value list. Read ECT sensor voltage. Voltage should be approximately 5 volts. If voltage is within specification, go to step  6. If voltage is not within specification, leave harness connector disconnected, and go to next step.
  5. Turn ignition off. Check for contact resistance and oxidation at ECM harness connector. Repair as necessary. Ensure ECM is securely connected. Turn ignition on. Using scan tool in DIAGNOSTIC MODE, scroll through value list. Read ECT sensor voltage parameter. Voltage should be approximately 5 volts. If voltage is within specification, DTC was caused by loose connection in ECM harness connector. Go to step  8. If voltage is not within specification, check for short in circuit between ECT sensor harness connector terminal No. 1 and ECM terminal A31. Repair as necessary. After repairs go to step  8.
  6. Turn ignition off. Wait approximately 3 minutes (5 minutes for vehicles equipped with immobilizer). Disconnect ECT sensor harness connector. Using DVOM, measure resistance between ground and ECT sensor harness connector terminal No. 2. Resistance should be approximately zero ohms. If resistance is not within specification, go to next step. If resistance is within specification, replace ECT sensor. After repairs, go to step  8.
  7. Turn ignition off. Check for contact resistance and oxidation at ECM harness connector. Repair as necessary. Using DVOM, measure resistance between ground and ECT sensor harness connector terminal No. 2. Resistance should be approximately zero ohms. If resistance is not within specification, check for open in circuit between ECT sensor harness connector terminal No. 2 and ECM terminal A18. Repair as necessary. After repairs, go to next step. If resistance is within specification, DTC was caused by loose connections in ECM connector. Go to next step.
    8. NOTE: Use of external infrared thermometer can be used to monitor engine coolant temperature in place of Volvo temperature box (999 5281) and Volvo temperature sensor (999 5282).
  8. Turn ignition off. Reconnect all connectors and components. Connect DVOM with Volvo temperature box (999 5281) and Volvo temperature sensor (999 5282). Carefully remove expansion tank cap. Clamp hose between radiator and thermostat. Loosen hose clamp and disconnect hose from thermostat housing. Insert sensor in thermostat housing and reinstall hose. Remove hose clamp. Start engine and warm until thermostat is open. Using scan tool in DIAGNOSTIC MODE, read ECT sensor parameter. If ECT sensor is within specification, fault was corrected. If reading is not within specification, repeat test starting with step  1.
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