Cold Advance Control Check
The cold advance control (CAC) circuit is designed to advance injection timing about 4° during cold operation. The circuit is activated by a temperature switch through a cold advance control relay to a cold advance solenoid. The switch is calibrated to open the circuit at coolant temperatures above 95°F (35°C).
Below 95°F (35°C), with the ignition switch "on", the cold advance solenoid is continuously energized without the engine running. Below this temperature, with the engine running, a timer in the relay starts to operate and closes the circuit to the cold advance solenoid for 35 seconds. When the solenoid is energized and the engine is running, housing pressure is decreased from 10 psi (69 kPa) to zero which advances the timing 4 degrees.
After 35 seconds, the cold advance solenoid is de-energized and the housing pressure is returned to 10 psi (69 kPa).