Diagnostic Aids

1995 GMC Suburban K2500, 7.4 NSECTION Diagnostic Aids

If glow plug relay was stuck in ON position, check for proper operation of glow plugs. When glow plugs are commanded on by scan tester, an internal PCM timer protects glow plug from damage by cycling them on for 3 seconds and then off for 12 seconds.

Fig 1: DTC 29 Schematic (6.5L Diesel) Glow Plug Relay Circuit Fault
G95D26966
RENDER: 1.0x

NO RELATED

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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.