Cold Advance Control

The cold advance control circuit is designed to advance injection pump timing about 4 degrees during cold engine operation. ECM activates this circuit through the cold advance relay to energize the cold advance solenoid. The ECM opens the circuit when coolant temperature is greater than 95°F (35°C).

When coolant temperature is less than the switching point and with ignition on, the cold advance solenoid is continuously energized without the engine running. When coolant temperature is less than the switching point and with the engine running, injection pump housing pressure is decreased from 10 psi (.7 kg/cm² ) to zero, which advances injection pump timing by about 4 degrees. As engine warms, the cold advance solenoid is de-energized and the injection pump housing pressure is returned to 10 psi (.70 kg/cm² ).