Diesel Cold Advance System Check: Notes
WARNING: This page does not describe the selected car, but rather 35 other vehicles, including the 1992 Pontiac Trans Sport, 1992 Oldsmobile Silhouette, 1992 Oldsmobile Bravada, 1992 GMC Yukon, and 1992 GMC Vandura Special. However, it is still accessible from the selected car via links, so may be relevant.
With ignition on voltage is supplied to the cold advance relay through the 20-amp GAGES fuse. When coolant temperature is less than 80°F (27°C), as sensed by the coolant temperature sensor, the ECM provides a ground at terminal C6. See Figure. Grounding terminal C6 energizes the cold advance relay, closing the relay contacts and supplying 12 volts to the cold advance solenoid (in the injection pump), and the glow plug controller. The cold advance solenoid is now energized, causing injection pump timing to be advanced about 4 degrees.