Diagnostic Aids

2000 Chevrolet Chevy Express G3500, Van Passenger, 7.4 JSECTION Diagnostic Aids

DTC could be caused by an IAC valve which is stopped and cannot respond to VCM, a throttle stop screw which has been tampered with, or a damaged throttle or linkage.

A slow, unstable or fast idle could be caused by a non-IAC valve system problem that cannot be overcome by IAC valve. See appropriate TROUBLE SHOOTING - NO CODES article. Out of range control IAC scan tool counts will be greater than 60 if idle is too low and zero if idle is too high. Check for fuel system too lean and rich. Check throttle body bore for foreign material. IAC reset is done with scan tool miscellaneous functions mode.

RENDER: 1.0x

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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.