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HOMESERVICE MANUALSCHEVROLET1998SUBURBAN K2500, 7.4 J, PART TIMEREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 18 (ENGINE CONTROLS - BASIC DIAGNOSTIC PROCEDURES - 6.5L DIESEL)ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECKMALFUNCTION INDICATOR LIGHT (MIL)
1998 Chevrolet Suburban K2500, 7.4 J, Part Time

Malfunction Indicator Light (Mil)

1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Malfunction Indicator Light (Mil)
WARNING: This page does not describe the selected car, but rather 10 other vehicles, including the 1997 GMC Yukon, 1997 GMC Suburban, 1997 GMC Pickup, 1997 GMC Cab & Chassis, and 1997 GMC C3500 HD. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform On-Board Diagnostic (OBD) System Check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK  . After performing OBD system check, go to next step.
  2. Attempt to start engine. If engine starts, go to next step. If engine does not start, go to step 6).
  3. Check fuse No. 4 (Gauges). If fuse if faulty, go to step 14). If fuse is okay, go to next step.
  4. Turn ignition on. Using a test light connected to ground, probe ignition feed terminal at instrument cluster connector. See the WIRING DIAGRAMS article. If test light illuminates, go to step 5). If test light does not illuminate, go to step 11).
  5. Turn ignition off. Disconnect Blue PCM harness connector. Turn ignition on. Using a fused jumper wire connected to ground, jumper MIL control circuit at PCM connector terminal. See the WIRING DIAGRAMS article. If MIL illuminates, go to step 9). If test light does not illuminate, go to step 10).
  6. Check fuses to PCM ignition and battery feed circuit. If fuses are okay, go to next step. If fuse(s) are faulty, go to step 13).
  7. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a test light connected to ground, probe PCM harness connector ignition and battery feed circuits. See the WIRING DIAGRAMS article. If test light illuminates on both circuits, go to next step. If test light does not illuminate on both circuits, go to step 12).
  8. Check for faulty or poor PCM ground connections. Repair as necessary. After repairs, go to step 20). If ground connections are okay, go to next step.
  9. Check for poor connection at PCM harness connector. Repair as necessary. After repairs, go to step 20). If connector is okay, go to step 15).
  10. Check for open in MIL control circuit. Repair as necessary. After repairs, go to step 20). If circuit is okay, go to step 16).
  11. Repair open in ignition feed circuit to instrument cluster. After repairs, go to step 20).
  12. Locate and repair open in PCM battery feed or ignition circuit. Repair as necessary. After repairs, go to step 20).
  13. Locate and repair short to ground in PCM ignition feed circuit or PCM battery feed circuit. Repair as necessary. After repairs, go to step 20).
  14. Locate and repair short to ground in instrument cluster ignition feed circuit. After repairs, go to step 20).
  15. Replace PCM. Perform PCM relearn procedures. After repairs, go to step 20).
  16. Check for poor connection at MIL control circuit to instrument cluster connector. Repair as necessary. After repairs, go to step 20). If circuit is okay, go to next step.
  17. Remove instrument cluster assembly. Inspect MIL bulb. If bulb is okay, go to step 19). If bulb is faulty, go to next step.
  18. Replace MIL bulb. After replacing bulb, go to step 20).
  19. Replace instrument cluster. After repairs, go to step 20).
  20. Using scan tool, select DTC, CLEAR INFO function. Attempt to start engine. If engine starts and continues to run, go to next step. If engine does not start, or starts and dies/stalls, go to step 2).
  21. Warm engine to normal operating temperature. Using scan tool, select DTC, FAILED THIS IGN function. Diagnose any DTC present. See the TESTS W/CODES article. If DTC(s) are not present, go to next step.
  22. Select CAPTURE INFO, REVIEW INFO function. If DTC(s) are present. Diagnose any DTC present. See the TESTS W/CODES article. 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.