Low Coolant Indicator (Diesel)
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 1997 GMC Savana Special, 1997 GMC Savana Camper Special, 1997 GMC Savana, 1997 Chevrolet RV Cutaway, and 1997 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
Warning system consists of radiator-mounted sensor, low coolant module, and warning light. When coolant level is low in radiator, sensor resistance is high. Module senses high resistance and turns on LOW COOLANT warning light. As a bulb check, light comes on when ignition is turned on. If no problem exists, light goes out when engine starts.