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Home >> Mazda >> 1999 >> B2500 SX, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 4 (Engine Controls - Self-Diagnostics - EEC-V - 6.8L (99S E Series & 99S F350 To F550)) >> System Tests >> Test NB: Malfunction Indicator Light (Mil) >> Diagnostic Aids

Diagnostic Aids

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Perform this test when instructed during QUICK TEST or if directed by other test procedures. This test is used to diagnose the following:

NOTE: If vehicle will not start, go to TEST A .

  1. MIL Always On

    If any KOEO or Continuous Memory DTCs are present, service DTCs as necessary before continuing. If no DTCs are present, turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector pins No. 2 and No. 51 or 103 (PWR GND). If resistance is less than 5 ohms, repair short in MIL circuit between PCM connector pin No. 2 and MIL. If resistance is 5 ohms or more, replace PCM.

  2. MIL Does Not Come On

    Turn ignition on. Measure voltage between ground side of MIL fuse and negative battery terminal. If voltage is 10.5 volts or less, go to next step. If voltage is more than 10.5 volts, go to step  4.

  3. Check For B+ At Fuse

    Measure voltage between positive side of MIL fuse and negative battery terminal. If voltage is 10.5 volts or less, repair open in MIL or B+ circuit. If voltage is more than 10.5 volts, replace MIL fuse. Recheck MIL operation.

  4. Check For B+ At MIL Bulb

    Turn ignition off. Disconnect instrument cluster connector. Turn ignition on. Measure voltage between B+ circuit terminal at instrument cluster wiring harness connector and negative battery terminal. If voltage is more than 10.5 volts, go to next step. If voltage is 10.5 volts or less, repair open in fuse, MIL bulb or B+ circuit to instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT in appropriate lemon-25® manual.

  5. Check Continuity Of MIL Circuit

    Turn ignition off. Disconnect PCM 104-pin connector. Inspect connector for loose, damaged or corroded terminals. Repair as necessary. Measure resistance between PCM connector pin No. 2 and MIL terminal at instrument cluster wiring harness connector. If resistance is 5 ohms or more, repair open in MIL circuit. If resistance is less than 5 ohms, check MIL bulb and instrument cluster. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Repair as necessary. If no problems are found, replace PCM.
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