GMC 2003 Sierra - Manual (Page 199)

The foil owing situations can causa the Irflnsmisson to
operate
at higher temperatures:
• Toiflfing a trailer
• Hot culside air temperatures
• Hauling a large or heavy toad
• Low transmission fluid level
• High iransmissfcin fluid level
• Restricted air flow to the radiator and the auxiliary
transmission oil cooler (Л equipped),
A lemporaiy solution to hotter transmission operating
lernperalures may Ъе lo let Ihe transmission cool down.
If the iransmission is operated at higher temperatures
on a frequent basis, see Scftecfuied M aintensncs
ОЛ page 6-5 ior the proper transmission maintenance
Intervals.
Malfunction Indicator Lamp
Check Engine Light
Vour vehicle is equipped
with a eomputar which
rnonitors operation of Ihe
fuel, ignition and emission
control systems.
This system is called OSD ll (On-Board
Diggncstics-Sacond Ganeralion) and is Intended to
assure thal emissions are
at accepiabla levels for the
life ol the vehicle, helpirrg to produce a deanet
envi room enl. The Check Engine light ccmas on to
indicate [hat ihere is a problem and service is reguired-
Maltunctions often will be indicated by the system
before any problem Is apparent. This may prevent more
sedous damagp to your vehicie. This system is also
designed to assist your service technician In correctly
diagnosing any melfunctton.
Notice: ft you keep driving your vehicle with this
light on, after a whiter your emissloin controls
may not work as welL your tuel economy may not
be as good and your engine may not run as
smoothly. This coutd lead to costly repairs that may
not be covered by your warranty.
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