Power Circuits

1996 Cadillac Seville STSSECTION Power Circuits
  1. Using a voltmeter, check for battery voltage between PCM constant battery power terminals and ground. 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 switch to the ON position. 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 the START position. Battery voltage should be present between PCM start terminal and ground ONLY when ignition switch is in the START position.
  4. If voltage is not present, check fuse(s). If fuse is okay, check for an open in wiring between fuse and PCM, or check for a defective ignition switch.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.