2000 GMC Sierra 1500 Pickup Owner's Manual - Page 156

yellowblue Engine Coolant Temperature Gage This gage shows the engine coolant temperature. Transmission Temperature Gage (If Equipped) If your vehicle has a heavy duty automatic transmission, you will have a transmission temperature gage. It also provides an indicator of how hard your vehicle is working. During a majority of the operation, the gage will read 210_F (100_C) or less. If you are pulling a load or going up hills, it is normal for the temperature to fluctuate and approach the 250_F (122_C) mark. If the gage reaches the 260_F (125_C) mark, it indicates that the cooling system is working beyond its capacity. The "Problems on the Road," section of this manual shows what to do. See "Engine Overheating" in the Index. When your ignition is on, the gage shows the temperature of the transmission fluid. The normal operating range is from 100_F (38_C) to about 265_F (130_C). At approximately 265_F (130_C), the message center will display a TRANS FLUID HOT message and the transmission will enter a transmission protection mode. When the transmission enters the protection mode, you may notice a change in the transmission shifting patterns. The transmission will return to normal shifting patterns when the transmission fluid temperature falls below 260_F (127_C). 2-78