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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 21 (BODY CONTROL MODULES)SELF-DIAGNOSTIC SYSTEMENGINE ELECTRICAL SYSTEM DIAGNOSTIC SYSTEM CHECK
1999 GMC Forward Control 5.7 R, Automatic

Engine Electrical System Diagnostic System Check

1999 GMC Forward Control 5.7 R, AutomaticSECTION Engine Electrical System Diagnostic System Check
WARNING: This page is about a different car, the 2002 Chevrolet Monte Carlo, 2002 Chevrolet Impala, 2001 Chevrolet Monte Carlo, and 2001 Chevrolet Impala. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Use this check as starting point for any engine electrical system complaint.
  1. Ensure battery is in good operating condition. See appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS. Repair as necessary. If battery is okay, go to next step.
  2. Turn ignition switch to OFF position. Connect scan tool to Data Link Connector (DLC). Turn ignition switch to RUN position. If scan tool powers up, go to next step. If scan tool does not power up, go to TEST D: SCAN TOOL DOES NOT POWER UP  under SYSTEM TESTS.
  3. Turn ignition switch to RUN position. Using scan tool, attempt to establish communications with following modules:
    • Body Control Module (BCM)
    • Powertrain Control Module (PCM)
    • Electronic Brake Control Module (EBCM)
    • Inflatable Restraint & Sensing Diagnostic Module (SDM)
    • Radio
    If communication is established with all modules, go to next step. If communication cannot be established any module, go to TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE  under SYSTEM TESTS.
  4. Select scan tool display DTCs function for following control modules:
    • Body Control Module (BCM)
    • Powertrain Control Module (PCM)
    • Electronic Brake Control Module (EBCM)
    • Inflatable Restraint Sensing & Diagnostic Module (SDM)
    If scan tool displays any DTCs, go to next step. If scan tool does not display any DTCs, perform appropriate symptom test. See SYSTEM TESTS in appropriate GENERATORS & REGULATORS article in STARTING & CHARGING SYSTEMS.
  5. Using scan tool, retrieve DTCs. If DTCs U1000-U1305 are not present, go to next step. If DTCs U1000-U1305 are present, go to TEST C: SCAN TOOL DOES NOT COMMUNICATE WITH CLASS 2 DEVICE  under SYSTEM TESTS.
  6. Check for DTC B1000, B2058, B2947, B2948, B2957, B2960, B3031 or B3032. If scan tool displays DTC B1000, B2058, B2947, B2948, B2957, B2960, B3031 or B3032, go to DIAGNOSTIC TROUBLE CODE DEFINITIONS . Repair as necessary. If scan tool does not display DTC B1000, B2058, B2947, B2948, B2957, B2960, B3031 or B3032, perform appropriate test. See DIAGNOSTIC TROUBLE CODE DEFINITIONS . Repair as necessary.
RENDER: 1.0x

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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.