Diagnostic Procedures

1998 Chevrolet Suburban K2500, 7.4 J, Part TimeSECTION Diagnostic Procedures
WARNING: This page is about a different variant/trim than selected.
  1. Perform POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECKΒ , then go to next step.
  2. If engine knock can be heard, repair mechanical problem before proceeding. Install scan tool. Operate vehicle within the conditions for setting this DTC. Using scan tool, monitor SPECIFIC DTC for this DTC. If scan tool indicates that this DTC FAILED THIS IGN?, go to step 4). If scan tool does not indicate that this DTC FAILED THIS IGN?, go to next step.
  3. Turn ignition on, with engine off. Using scan tool, review and record FAILURE RECORDS data. Operate vehicle within FAILURE RECORDS conditions. Using scan tool, monitor SPECIFIC DTC for this DTC. If scan tool indicates that this DTC FAILED THIS IGN?, go to next step. If scan tool does not indicate that this DTC FAILED THIS IGN?, see DIAGNOSTIC AIDS.
  4. Check KS signal circuit for incorrect routing near secondary wires and repair as necessary. If a problem is found, go to step 8). If no problem is found, go to next step.
  5. Check if KS module is fully seated or incorrectly installed and repair as necessary. If a problem is found, go to step 8). If no problem is found, go to next step.
  6. Replace KS module. Operate vehicle within the conditions for setting this DTC. Using scan tool, monitor SPECIFIC DTC for this DTC. If scan tool indicates that this DTC FAILED THIS IGN?, go to next step. If scan tool does not indicate that this DTC FAILED THIS IGN?, go to step 8).
  7. Replace VCM. Program replacement VCM using required equipment. After replacing VCM, go to next step.
  8. Using scan tool, select DTC, CLEAR INFO. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter this DTC. Operate vehicle within the conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2).
  9. Using scan tool, select CAPTURE INFO, REVIEW INFO. If any undiagnosed DTC(s) are displayed, go to applicable DTC test.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.