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Home › Mitsubishi › 2002 › Montero Sport LS, 4WD › Repair and Diagnosis › Engine Performance › System › Engine Controls - Self-Diagnostics › Diagnostic Tests › DTC P0181: Fuel Temperature Sensor Circuit Range/Performance Problem › Test Procedure

Test Procedure

NOTE: A DTC could be output if the engine and radiator have been flushed repeatedly when the engine coolant temperature was high (or fuel temperature was high). Because this is not a failure, erase the DTC. Then test drive vehicle following OBD-II drive cycle other monitor pattern. See OTHER MONITOR  under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Check for DTCs. Verify DTC is not output.
  1. Turn ignition on. Using scan tool, check data list item No. 4A (fuel temperature sensor). Air temperature, as measured with a thermometer, and fuel temperature displayed on scan tool should be within 10 percent of each other. If temperature is not as specified, go to next step. If scan tool readings are as specified, problem is intermittent. See INTERMITTENT DIAGNOSTIC TROUBLE CODES . If scan tool readings are not as specified, go to next step.
  2. Turn ignition on. Measure voltage between ground and fuel gauge unit 3-pin connector terminal No. 1 (Yellow/Blue wire) by backprobing. See Figure. See FUEL TEMPERATURE SENSOR VOLTAGE SPECIFICATIONS . If voltage is as specified, go to next step. If voltage is not as specified, go to step  5.
    FUEL TEMPERATURE SENSOR VOLTAGE SPECIFICATIONS

    Volts Fuel Temperature °F (°C)
    2.7 - 3.1 32 (0)
    2.1 - 2.5 68 (20)
    1.6 - 2.0 104 (40)
    0.8 - 1.2 176 (80)
  3. Turn ignition off. Disconnect fuel gauge unit 3-pin connector. Check fuel gauge unit connector for loose, damaged or corroded terminals. If problem exists, repair or replace connector. Go to step  12. If problem does not exist, go to next step.
  4. Turn ignition on. Using scan tool, check data list item No. 4A (fuel temperature sensor). Air temperature, as measured with a thermometer, and fuel temperature displayed on scan tool should be within 10 percent of each other. If temperature is not as specified, go to next step. If scan tool readings are as specified, problem is intermittent. See INTERMITTENT DIAGNOSTIC TROUBLE CODES . If scan tool readings are not as specified, replace PCM. Go to step  12.
  5. Turn ignition off. Disconnect fuel gauge unit 3-pin connector. Check fuel gauge unit connector for loose, damaged or corroded terminals. If problem exists, repair or replace connector. Go to step  12. If problem does not exist, go to next step.
  6. Turn ignition on. Measure voltage between ground and fuel temperature sensor 3-pin connector terminal No. 1 (Yellow/Blue wire). There should be between 4.5-4.9 volts. If voltage is as specified, go to step  8. If voltage is not as specified, go to next step.
  7. Turn ignition off. Disconnect PCM connector C-90. See Figure. Check PCM connector C-90 for loose, damaged or corroded terminals. If problem exists, repair or replace connector. Go to step  12. If problem does not exist, replace PCM and go to step  12.
  8. Check for continuity between ground and fuel gauge unit connector terminal No. 3 (Black wire). If continuity exists, go to next step. If continuity does not exist, check 20-pin intermediate connector E-44 for damage and repair as necessary. If 20-pin intermediate connector E-44 is OK, repair open circuit in Black wire between fuel gauge unit and ground. Go to step  12.
  9. Measure resistance between fuel gauge unit connector terminals No. 1 and 3 (component side). Resistance should be 0.5-12.0 k/ohms. If resistance is as specified, go to next step. If resistance is not as specified, replace fuel temperature sensor. Go to step  12.
  10. Turn ignition off. Disconnect PCM connector C-90. Check PCM connector C-90 for loose, damaged or corroded terminals. If problem exists, repair or replace connector. Go to step  12. If problem does not exist, go to next step.
  11. Check 11-pin intermediate connector C-85 and 20-pin intermediate connector E-44 for damage and repair as necessary. See Figure and Figure . If 11-pin intermediate connector C-85 and 20-pin intermediate connector E-44 are OK, check continuity between fuel temperature sensor connector terminal No. 1 (Yellow/Blue wire) and PCM connector C-90 terminal No. 51 (Yellow/Red wire). If problem exists, repair Yellow/Blue wire or Yellow/Red wire. Go to step  12. If problem does not exist, replace PCM. Go to step  12.
  12. Test drive vehicle following OBD-II drive cycle other monitor pattern. See OTHER MONITOR  under OBD-II DRIVE CYCLES under VERIFYING REPAIRS. Check for DTCs. If DTC P0181 is output, go to step  1 and retry test procedure. If DTC P0181 is not output, inspection is complete.
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