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Home >> Mazda >> 2002 >> B4000 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 or FLI PID is 1.23-2.25 volts, perform the following:
    • For DTC P0460, fault is intermittent. See INTERMITTENT  under SYSTEM TESTS.
    • If referenced here from symptom trouble shooting, replace faulty fuel gauge. Go to step  12 .
    If voltage or FLI PID is not 1.23-2.25 volts, go to step  12 .

  5. Check Fuel Pump Module Resistance

    Turn ignition off. Disconnect fuel pump module electrical connector. Measure resistance between FLI circuit (Yellow/White wire) and CASE GND circuit (Black/Orange wire) at fuel pump module connector (component side). See Fig 1 . If resistance is 15-160 ohms, go to next step. If resistance is not 15-160 ohms, check for a stuck fuel level float on fuel pump module. Repair as necessary. If fuel level float is not stuck, replace faulty fuel pump assembly. 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 connector (C215) to fuel gauge. With KOEO, measure voltage between FLI circuit (Yellow/White wire) at fuel pump harness connector and battery negative terminal. See Fig 1 . Observe voltage. Turn ignition off. If voltage is more than 5 volts, go to next step. If voltage is 5 volts or less, go to step  8 .

  7. Check FLI Circuit For Short To VPWR In Harness

    Disconnect PCM connector. With KOEO, measure voltage between FLI circuit (Yellow/White wire) at fuel pump harness connector and battery negative terminal. See Fig 1 . Observe voltage. Turn ignition off. If voltage is more than 10.5 volts, repair short circuit. See WIRING DIAGRAMS article. Go to step  12 . If voltage is 10.5 volts or less, replace faulty PCM. Go to step  12 .

  8. Check FLI Circuit For Short To PWR GND In Harness

    Turn ignition off. Disconnect PCM connector. Install breakout box, leaving PCM disconnected. Measure resistance between breakout box terminal No. 12 (FLI circuit) and battery negative terminal. If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short between FLI circuit (Yellow/White wire) and CASE GND circuit (Black/Orange wire). See WIRING DIAGRAMS article. 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 harness connector. See Fig 1 . If resistance is more than 10,000 ohms, go to next step. If resistance is 10,000 ohms or less, repair short between FLI circuit and CASE GND. See WIRING DIAGRAMS article. Go to step  12 .

  10. Check FLI Circuit For Open In Harness

    If here from Symptom Trouble Shooting, measure resistance of FLI circuit between breakout box terminal No. 12 and fuel pump 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 (C-215) (Yellow/White wire). If resistance is less than 10 ohms, go to next step. If resistance is 10 ohms or more, repair open circuit. See WIRING DIAGRAMS article. Go to step  12 .

  11. Check CASE GND Circuit For Open In Harness

    Measure resistance of CASE GND circuit between fuel pump module connector (Black/Orange wire) and vehicle battery. If resistance 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 is 10 ohms or more, repair open circuit. See WIRING DIAGRAMS article. Go to next step.

  12. Verify Trouble Shooting Of DTCs Completed

    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 DTCs are set, trouble shooting is complete.
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