DTC 17, High Resolution Circuit Fault: Notes

1995 GMC Rally G2500, 4.3 ZSECTION Notes

Optical sensor provides a high resolution signal to PCM by counting pulses on sensor disk located in injection pump. High resolution signal is one of the most important inputs used by PCM for fuel control and timing. DTC 17 will set when 8 pump cam reference pulses occur without an increase in high resolution counts (internal to PCM). PCM will default to backup fuel.

NOTE: Test numbers refer to numbers on diagnostic chart.
  1. This step determines if a 5-volt reference is present.
  2. This step checks ground circuit.
  3. This step checks if sensor is sending a signal back to PCM.
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.