Coolant Level Control

WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2003 GMC Yukon XL, 2003 GMC Yukon, 2003 Chevrolet Tahoe, 2003 Chevrolet Suburban, and 2003 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.

The engine cooling system contains an engine coolant level switch to alert the driver in the event of a coolant loss. The powertrain control module (PCM) sends out a coolant loss signal over the coolant level switch signal circuit. When the engine coolant level switch reads a low coolant level in the fill tank, the switch opens. The instrument cluster has an internal logic which displays information on the message center. The logic receives power from the fuse block on 3 individual power circuits; ignition 3 voltage, off/run/crank voltage, and ignition 1 voltage circuit through the body wiring harness junction block. The message center receives it's power from engine wiring harness junction block on the battery positive voltage circuit. Ground is provided by the ground circuits via the body wiring harness junction block and the engine wiring harness junction block. The message center receives the signal from the logic and displays the LOW COOLANT message. The message is a continuous display shown in amber.