GMC 1995 Jimmy Owner's Manual page 216

If No Steam Is Coming From Your Engine
If you get the overheat warning but see or hear no steam, the problem may
not be too serious. Sometimes the engine can get a little too hot when you:
0
Climb a long hill on a hot day.
0
Stop after high speed driving.
Idle for long periods in traffic.
0
Tow a trailer. See "Driving on Grades" in the Index.
If you get the overheat warning with no sign of steam, try this for
a
minute
or so:
1 . Turn off your air conditioner.
2. Turn on your heater to full hot at the highest fan speed and open the
3. If you're in a traffic jam, shift to NEUTRAL (N); otherwise, shift to the
window as necessary.
highest gear while driving
-
AUTOMATIC OVERDRIVE
(a)
or
DRIVE (D) for automatic transmissions.
If you no longer have the overheat warning, you can drive. Just to be safe,
drive slower for about ten minutes. If the warning doesn't come back on,
you can drive normally.
If the warning continues, pull over, stop, and park your vehicle right away.
If there's still no sign of steam, push the accelerator until the engine speed is
about twice as fast as normal idle speed. Bring the engine speed back to
normal idle speed after two or three minutes. Now see if the warning stops.
But then, if you still have the warning, turn
oJf
the engine and get everyone
out o f
the vehicle until it cools down.
You may decide not to lift the hood but to get service help right away.
When you decide it's
safe to lift the hood,
here's what you'll see:
A. Coolant recovery
tank
B, Radiator pressure
cap
C. Engine fan