GMC 2002 Sierra - Manual (Page 187)

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Engine Coolant Temperature Gage
United States Canada
This gage shows the engine coolant temperature.
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.
See “Engine Overheating” in the Index.
Transmission Temperature Gage
(If Equipped)
United States Canada
Your vehicle may be equipped with a transmission
temperature gage.
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).