Diesel Cold Advance System Check: Notes

1991 GMC Jimmy 5.7 K, Automatic, 4L60/MD8SECTION Notes

With ignition on and coolant temperature less than 80°F (27°C), the ECM grounds circuit No. 905 to the cold advance relay. Grounding circuit No. 905 turns on cold advance relay to supply 12 volts to the cold advance solenoid (in the injection pump), and glow plug controller. The cold advance solenoid is now energized, causing injection pump timing to be advanced about 4 degrees.

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:

  • 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.