Code No. P0183: Fuel Temperature Sensor Circuit High Input




OPERATION



  • A power voltage of 5 V is applied to the fuel temperature sensor output terminal (terminal No. 1) of the air flow sensor connector from the engine-ECU (terminal No. 55).
  • The power voltage is earthed to the engine-ECU (terminal No. 79) from the fuel temperature sensor (terminal No. 2).

FUNCTION



  • The fuel temperature sensor converts the intake air temperature into a voltage and inputs the voltage signal to the engine-ECU.
  • In response to the signal, the engine-ECU corrects the fuel injection amount, etc.
  • The fuel temperature sensor is a kind of resistor, which has characteristics to reduce its resistance as the intake air temperature rises. Therefore, the sensor output voltage varies with the fuel temperature, and becomes lower as the fuel temperature rises.

TROUBLE JUDGMENT


Check Conditions
  • Battery positive voltage is 8 - 16 V
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up.
Judgment Criterion
  • The fuel temperature sensor output voltage is 4.95 V or more for 0.5 second.

PROBABLE CAUSES



  • Failed fuel temperature sensor
  • Open circuit or harness damage in fuel temperature sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

  • Item 21: Fuel temperature sensor
OK: At ambient temperature (fuel temperature) or equivalent.

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2.

STEP 2. Connector check: A-46 fuel temperature sensor connector

Q. Is the check result normal?

Go to Step 3.

Repair or replace the connector.

STEP 3. Check fuel temperature sensor itself.

  • Check fuel temperature sensor itself (Refer to ).

Q. Is the check result normal?
Go to Step 4.
Replace the fuel temperature sensor.

STEP 4. Perform voltage measurement at A-46 fuel temperature sensor connector.


  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 and earth.
OK: 4.5 - 4.9 V

Q. Is the check result normal?

Go to Step 8.

Go to Step 5.

STEP 5. Connector check: C-105 engine-ECU connector

Q. Is the check result normal?

Go to Step 6.

Repair or replace the connector.

STEP 6. Check harness between A-46 (terminal No. 1) fuel temperature sensor connector and C-105 (terminal No. 55) engine-ECU connector.



  • Check output line for open circuit.

Q. Is the check result normal?

Go to Step 7.

Repair the damaged harness wire.

STEP 7. M.U.T.-III data list

  • Item 21: Fuel temperature sensor
OK: At ambient temperature (fuel temperature) or equivalent.

Q. Is the check result normal?
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Replace the engine-ECU. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, the vehicle equipped with the DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Emission Control - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).

STEP 8. Perform resistance measurement at A-46 fuel temperature sensor connector.


  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 2 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?

Go to Step 7.

Go to Step 9.

STEP 9. Connector check: C-105 engine-ECU connector

Q. Is the check result normal?

Go to Step 10.

Repair or replace the connector.

STEP 10. Check harness between A-46 (terminal No. 2) fuel temperature sensor connector and C-105 (terminal No. 79) engine-ECU connector.

  • Check earthing line for open circuit and damage.


Q. Is the check result normal?

Go to Step 7.

Repair the damaged harness wire.