2012 GMC Sierra Owner's Manual - Page 410

10-24 . . Vehicle Care vehicle distance from the vehicle in front. If the warning does not come back on, continue to drive normally. If the warning continues, pull over, stop, and park the vehicle right away. If there is no sign of steam, idle the engine for five minutes while parked. If the warning is still displayed, turn off the engine until it cools down. Also, see "Overheated Engine Protection Operating Mode" later in this section. This operating mode allows the vehicle to be driven to a safe place in an emergency. Driving extended km (mi) and/or towing a trailer in the overheat protection mode should be avoided. Notice: After driving in the overheated engine protection operating mode, to avoid engine damage, allow the engine to cool before attempting any repair. The engine oil will be severely degraded. Repair the cause of coolant loss, change the oil and reset the oil life system. See Engine Oil on page 10‑7. Idles for long periods in traffic Tows a trailer; see Trailer Towing on page 9‑78. If the ENGINE OVERHEATED STOP ENGINE or the ENGINE OVERHEATED IDLE ENGINE message appears with no sign of steam, try this for a minute or so: 1. Turn the air conditioning off. 2. Turn the heater on to the highest temperature and to the highest fan speed. Open the windows as necessary. 3. If stopped in a traffic jam, apply the brake, shift to N (Neutral); otherwise, shift to the highest gear while driving - D (Drive) or 3 (Third). If the temperature overheat gauge is no longer in the overheat zone or an overheat warning no longer displays, the vehicle can be driven. Continue to drive the vehicle slowly for about 10 minutes. Keep a safe Overheated Engine Protection Operating Mode If an overheated engine condition exists and the ENGINE POWER IS REDUCED message displays, an overheat protection mode which alternates firing groups of cylinders helps to prevent engine damage. In this mode, a loss in power and engine performance will be noticed. Engine Fan If the vehicle has a clutched engine cooling fan, when the clutch is engaged, the fan spins faster to provide more air to cool the engine. In most everyday driving conditions, the fan is spinning slower and the clutch is not fully engaged. This improves fuel economy and reduces fan noise. Under heavy vehicle