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HOMESERVICE MANUALSGMC1995SUBURBAN K2500, 6.5 FREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 131 (ENGINE CONTROLS - BASIC DIAGNOSTIC PROCEDURES - 4.3L)A-4 INJECTOR CIRCUIT DIAGNOSIS
1995 GMC Suburban K2500, 6.5 F

A-4 Injector Circuit Diagnosis

1995 GMC Suburban K2500, 6.5 FSECTION A-4 Injector Circuit Diagnosis
WARNING: This page does not describe the selected car, but rather 16 other vehicles, including the 1996 Chevrolet Chevy Van, 1995 GMC Vandura, 1995 GMC Sonoma, 1995 GMC Safari, and 1995 GMC Rally. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: This test only applies to vehicles equipped with a VCM.
  1. ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK . After performing OBD system check, go to next step.
  2. Disconnect injector connector at intake manifold. Turn ignition on. Using test light connected to ground, probe ignition feed circuits. See WIRING DIAGRAMS article. If test light illuminates, go to next step. If test light does not illuminate, go to step 7).
  3. Install injector test light to each injector circuit, one at a time. Crank engine. If injector test light flashes on each injector, check fuel injector(s). See FUEL SYSTEM in I -SYSTEM/COMPONENT TESTS article. If injector test light did not flash on an injector circuit, go to next step.
  4. If injector test light was on steady on an injector circuit, go to next step. If injector test light did not illuminate on an injector circuit, go to step 6).
  5. Install injector test to affected injector. Turn ignition off. Disconnect Blue and Red VCM connectors. Turn ignition on, with engine off. If injector test light turns off, go to step 11). If injector test light stays on, go to step 8).
  6. Check for open or short in battery circuit to affected injector. If circuit is open or shorted, go to next step. If circuit is okay, go to step 9).
  7. Repair circuit as necessary. After repairs, go to step 12).
  8. Repair short to ground in injector control circuit. After repairs, go to step 12).
  9. Check terminal contact at VCM connector. If terminal contact is faulty, go to next step. If terminal contact is okay, go to step 11).
  10. Repair terminal contact. After repairs, go to step 12).
  11. Replace VCM. Reprogram replacement VCM. After replacing VCM, go to next step.
  12. Using scan tool, select DTC, CLEAR INFO mode. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start or starts and stalls/dies, go to step 14).
  13. Warm engine to normal operating temperature. Using scan tool, select DTC, FAILED THIS IGN mode. If other DTC(s) are present, diagnose affected DTC(s). If no other DTC(s) are present, go to next step.
  14. Using scan tool, select CAPTURE INFO, REVIEW INFO. If additional undiagnosed DTC(s) are present, diagnose affected DTC(s). If DTC(s) are not present, system is okay.
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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.