78 GETTING TO KNOW YOUR INSTRUMENT PANEL BASE / MIDLINE INSTRUMENT CLUSTER — DIESEL D IESEL I NSTRUMENT C LUSTER 1. Tachometer 2. Engine Coolant Temperature This gauge shows the engine coolant temperature. The gauge pointer will likely show higher temperatures when driving in hot weather, up mountain grades, or in heavy stop and go traffic. If the red Warning Light turns on while driving, safely bring the vehicle to a stop, and turn off the engine. DO NOT operate the vehicle until the cause is corrected. Indicates the engine speed in revolutions per minute (RPM x 1000).