Diagnostic Procedures

2000 Chevrolet Cab & Chassis C2500, 6.5 F, AutomaticSECTION Diagnostic Procedures
WARNING: This page is about a different car, the 1999 GMC Sierra and 1999 Chevrolet Silverado. However, it is still accessible from the selected car via links, so may be relevant.
  1. If BCM diagnostic system check has been performed, go to next step. If BCM diagnostic system check has not been performed, perform BCM diagnostic system check. See BCM DIAGNOSTIC SYSTEM CHECK  under SYSTEM TESTS.
  2. Set parking brake. Turn ignition off. Turn thumb wheel (dome light dimmer) completely down to MAXIMUM DIM position. Using scan tool, monitor current DTCs. Remove ILLUM fuse (10-amp) located in Left Bussed Electrical Center (LBEC). If scan tool displays DTC B2613 as current, go to next step. If scan tool does not display DTC B2613 as current, go to step  4 .
  3. Disconnect Purple BCM connector C3 while monitoring current DTCs. See Figure . If scan tool displays DTC B2613 as current, go to step  8 . If scan tool does not display DTC B2613 as current, go to step  5 .
  4. Reinstall ILLUM fuse in LBEC. Disconnect headlight and panel dimmer switch while monitoring current DTCs. If scan tool displays DTC B2613 as current, go to step  6 . If scan tool does not display DTC B2613 as current, go to step  7 .
  5. Repair short to battery voltage in Gray wire between Purple BCM connector C3 terminal A5 and LBEC connector C1 terminal B4. See WIRING DIAGRAMS  . After repairs, go to step  9 .
  6. Repair short to battery voltage in Dark Green wire between headlight and panel dimmer switch connector terminal "K" and LBEC connector C1 terminal C4. See WIRING DIAGRAMS  . After repairs, go to step  9 .
  7. Replace headlight and dimmer switch assembly. See HEADLIGHT & DIMMER SWITCH  under REMOVAL & INSTALLATION. After replacing switch, go to step  9 .
  8. Replace BCM and program. See BODY CONTROL MODULE (BCM)  under REMOVAL & INSTALLATION.
  9. Reconnect all components. Clear DTCs. See CLEARING DIAGNOSTIC TROUBLE CODES (DTCS)  under SELF-DIAGNOSTIC SYSTEM.
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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.