1990 Chevrolet Suburban R2500, 5.7 K, Automatic, 3L80-HD/M40FACTORY OEM SERVICE PROCEDURE

Cold Advance Control

The cold advance control circuit is designed to advance injection pump timing about 4 degrees during cold engine operation. This circuit is activated by the ECM, through the cold advance relay, to energize the cold advance solenoid. The ECM opens the circuit when coolant temperature is above 95Β°F (35Β°C).

Below the switching point, and with ignition on, the cold advance solenoid is continuously energized without the engine running. Below the switching point and the engine running, injection pump housing pressure is decreased from 10 psi (.70 kg/cm2 ) to zero, which advances injection pump timing by about 4 degrees. As engine warms-up, the cold advance solenoid is de-energized and the injection pump housing pressure is returned to 10 psi (.70 kg/cm2 ).

Factory Service Tools

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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.

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