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Home >> Mazda >> 1998 >> 626 DX, Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Computerized Engine Controls >> Powertrain Control Module (Pcm) >> Power Circuit Checks
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Power Circuit Checks

  1. Using a voltmeter, check for battery voltage between PCM constant battery power terminals and ground. See appropriate wiring diagram in WIRING DIAGRAMS article to determine PCM power terminals. If battery voltage is not present, check PCM power supply fuse. If fuse is okay, check for open in power supply or PCM wiring.
  2. Turn ignition on. Using a voltmeter, check for battery voltage between PCM ignition power terminals and ground. If battery voltage is not present, check power supply fuse(s). If fuse is okay, check for an open in wiring between fuse and PCM, or check for a defective ignition switch.
  3. Connect voltmeter between ground and PCM start (crank) signal terminal. Turn ignition switch to START position. Battery voltage should be present between PCM start terminal and ground only when ignition switch is in START position. If voltage is not present, check fuse(s). If fuse is okay, check for open circuit in wiring harness between fuse and PCM. If wiring harness is okay, check for a defective ignition switch.
PCM LOCATIONS

Application Location
Millenia Below Center Of Instrument Panel
MPV Below Right Side Of Instrument Panel
626 Below Front Of Center Console
Protege Below Center Of Instrument Panel
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