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Home >> GMC >> 2002 >> C3500 HD 8.1 G, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System & Component Testing >> Computerized Engine Controls >> Pcm Power & Ground Check >> Power Circuits
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Power Circuits

  1. Check PCM connectors for corroded or loose connections. Repair as necessary. Disconnect PCM connectors. Using DVOM, check for battery voltage between chassis ground and continuous power terminal(s) at PCM harness connector(s). If battery voltage is present, go to next step. If battery voltage is not present, check for open fuse or fusible link. If fuse or fusible link is okay, check for open in wire between PCM terminal and power source.
  2. Turn ignition switch to RUN position. Using DVOM, check for battery voltage between chassis ground and ignition power terminals at PCM harness connector(s). If battery voltage is present, power circuits are okay. If battery voltage is not present, check IGN fuse. If fuse is okay, check for an open in wire between battery and ignition switch, and between ignition switch and PCM terminal. If wiring is okay, check for a defective ignition switch.
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