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Home >> Mazda >> 2003 >> B2300 Base, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P0460: Fuel Level Input Circuit Malfunction >> Diagnostic Procedures

Diagnostic Procedures

  1. If QUICK TEST was not performed, go to QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If QUICK TEST was performed, go to next step.
  2. DTC P0460: Check Fuel Tank Level -  With KOEO, observe and record fuel gauge reading. Access FLI PID, observe and record. If both fuel gauge and FLI PID indicate between slightly more than 1/4 (30 percent on FLI PID) and 3/4 (70 percent on FLI PID) filled, go to step  4 . If both fuel gauge and FLI PID do not indicate between slightly more than 1/4 (30 percent on FLI PID) and 3/4 (70 percent on FLI PID) filled, turn ignition off. Inspect fuel tank for leaks. Check for a damaged fuse for fuel pump to fuel gauge circuit:
    • For a damaged fuse without DTC P0460, check for CASE GND short to VPWR circuit.
    • For fuel gauge inoperative without a DTC P0460, see appropriate INSTRUMENT PANEL article in ACCESSORIES & EQUIPMENT.
    • For DTC P0460, go to next step.
  3. Check For Inadequate Fuel Level -  With KOEO, observe both fuel gauge and FLI PID while performing the following:
    • If fuel level is less than 1/3 (33 percent on FLI PID), add 2-3 gallons of fuel to fuel tank.
    • If fuel level is more than 3/4 (75 percent on FLI PID), drain 2-3 gallons of fuel from fuel tank.
    If either fuel gauge or FLI PID indicates a movement upward or downward as fuel was added or taken away, drive vehicle and rerun QUICK TEST  . If DTC P0460 is still present, go to next step. If either fuel gauge or FLI PID does not indicate a movement upward or downward as fuel was added or taken away, turn ignition off. Go to step  5 .
  4. Check FLI Circuit Voltage -  With KOER, access FLI V PID and observe. If voltage reading or FLI PID is 1.23-2.25 volts, perform the following:
    • For DTC P0460, fault is intermittent. See INTERMITTENT  testing under SYSTEM TESTS.
    • If referenced here from symptom trouble shooting, replace faulty fuel gauge. After repair, go to step  12 .
    If voltage reading or FLI PID is not 1.23-2.25 volts, go to step  12 .
  5. Check Fuel Pump Module Resistance -  Turn ignition off. Disconnect FPM 4-pin harness connector. Measure resistance between FLI circuit (Yellow/White wire) and CASE GND circuit (Black/Orange wire) at FPM 4-pin connector (component side). See Fig 1 . If resistance reading is 15-160 ohms, go to next step. If resistance reading is not 15-160 ohms, check for a stuck fuel level float on FPM. Repair as necessary. If fuel level float is not stuck, replace faulty fuel pump assembly. After repair, go to step  12 .
    Fig 1: Identifying Fuel Tank Unit 4-Pin Harness Connector
    G00110115Courtesy of MAZDA MOTORS CORP.
  6. Check FLI Circuit Voltage At Fuel Pump -  Disconnect instrument cluster 12-pin harness connector to fuel gauge. With KOEO, measure voltage between FLI circuit (Yellow/White wire) at fuel pump 4-pin harness connector and negative battery terminal. See Fig 1 . Turn ignition off. If voltage reading was more than 5 volts, go to next step. If voltage reading was 5 volts or less, go to step  8 .
  7. Check FLI Circuit For Short To VPWR In Harness -  Disconnect PCM 104-pin harness connector. With KOEO, measure voltage between FLI circuit (Yellow/White wire) at fuel pump 4-pin harness connector and negative battery terminal. See Fig 1 . Observe voltage. Turn ignition off. If voltage reading is more than 10.5 volts, repair short circuit. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. Go to step  12 . If voltage reading is 10.5 volts or less, replace faulty PCM. After repair, go to step  12 .
  8. Check FLI Circuit For Short To PWR GND In Harness -  Turn ignition off. Disconnect PCM 104-pin harness connector. Connect Breakout Box (49-UN01-130) to PCM harness connector only. See Figure . Measure resistance between breakout box terminal No. 12 (FLI circuit) and negative battery terminal. If resistance reading is more than 10,000 ohms, go to next step. If resistance reading is 10,000 ohms or less, repair short between FLI circuit (Yellow/White wire) and CASE GND circuit (Black/Orange wire). After repair, go to step  12 .
  9. Check FLI Circuit For Short To CASE GND In Harness -  Measure resistance between FLI circuit (Yellow/White wire) and CASE GND circuit (Black/Orange wire) at fuel pump module 4-pin harness connector. See Fig 1 . If resistance reading is more than 10,000 ohms, go to next step. If resistance reading is 10,000 ohms or less, repair short between FLI circuit and CASE GND. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to step  12 .
  10. Check FLI Circuit For Open In Harness -  If here from Symptom Trouble Shooting, measure resistance of FLI circuit (Yellow/White wire) between breakout box terminal No. 12 and fuel pump 4-pin harness connector. If not here from Symptom Trouble Shooting, measure resistance of FLI circuit between breakout box terminal No. 12 and instrument cluster 12-pin connector (Yellow/White wire). If resistance reading is less than 10 ohms, go to next step. If resistance reading is 10 ohms or more, repair open circuit. After repair, go to step  12 .
  11. Check CASE GND Circuit For Open In Harness -  Measure resistance of CASE GND circuit between FPM 4-pin harness connector (Black/Orange wire) and vehicle battery. If resistance reading is less than 10 ohms, replace fuel gauge or repair as necessary (if here from Symptom Trouble Shooting). Perform QUICK TEST  . If DTC P0460 is still set, replace faulty PCM. If resistance reading is 10 ohms or more, repair open circuit in Black/Orange wire between FPM 4-pin harness connector and negative battery terminal. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS. After repair, go to next step.
  12. Verify Trouble Shooting Of DTCs Completed -  Reconnect all electrical connectors. Clear DTC from PCM memory using scan tool. Perform QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If same DTC is present, replace faulty PCM. Repeat QUICK TEST  under SELF-DIAGNOSTIC SYSTEM. If any other DTC is present, go to applicable procedure for other DTCs. See DIAGNOSTIC TROUBLE CODE DEFINITIONS  . If no DTC is present, trouble shooting is complete.
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