GMC TopKick 2007 Owner's Manual page 287

If No Steam Is Coming From
Your Engine
An overheat warning, along with a low coolant
light, can indicate a serious problem. See
Low Coolant Warning Light on page 171 for
more information.
If you get an engine overheat warning with no
low coolant light, but see or hear no steam,
the problem may not be too serious. Sometimes
the engine can get a little too hot when you:
•
Climb a long hill on a hot day.
•
Stop after high-speed driving.
•
Idle for long periods in traffic.
If you get the overheat warning with no sign of
steam, try this for a minute or so:
1. In heavy traffic, let the engine idle in
NEUTRAL while stopped. If it is safe to
do so, pull off the road, shift to PARK (P) or
NEUTRAL and let the engine idle.
2. Turn on your heater to full hot at the highest fan
speed and open the windows as necessary.
3. If climbing a hill, downshift to raise engine and
fan speeds.
If you no longer have the overheat warning, you
can drive. Just to be safe, drive slower for
about 10 minutes. If the warning does not come
back on, you can drive normally.
If the warning continues and you have not
stopped, pull over, stop, and park your vehicle
right away.
If there is still no sign of steam, you can push down
the accelerator until the engine speed is about
twice as fast as normal idle speed for at least
three minutes while you are parked. If you still have
the warning, turn off the engine and get everyone
out of the vehicle until it cools down.
You may decide not to lift the hood but to get
service help right away.
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