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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 79 (ENGINE CONTROL SYSTEM SELF-DIAGNOSTICS - 3.4L)DIAGNOSTIC TESTSDTC P1374: 3X REFERENCE CIRCUITDIAGNOSTIC AIDS
1999 GMC Forward Control 5.7 R, Automatic

Diagnostic Aids

1999 GMC Forward Control 5.7 R, AutomaticSECTION Diagnostic Aids
WARNING: This page is about a different car, the 2002 Pontiac Grand Am, 2002 Oldsmobile Alero, 2002 Chevrolet Monte Carlo, and 2002 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.

DTC P1374 can be caused by secondary components leaking high voltage into the IC module.

Check for any of the following conditions:

  • Incorrect harness routing near secondary ignition components.
  • Ignition coil arcing to wiring harness or IC module Inspect the ignition coils for cracks, carbon tracking and other signs of damage.
  • Secondary ignition wires arcing to the wiring harness.
  • If the DTC is determined to be intermittent, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.

RENDER: 1.0x

NO RELATED

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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.