GMC 1995 Suburban Owner's Manual page 88

NOTICE:
Don't try to shift to PARK (P) if your vehicle is moving. If you
do, you could damage the transmission. Shift to PARK (P) only
when your vehicle is stopped.
Turn your ignition key to R U N .
Observe the GLOW PLUGS light. (This light may not come on if the
engine is hot.)
NOTICE:
If the GLOW PLUGS light stays on, it means that your vehicle
could have one of several problems, so you should have it
serviced right away.
2. As soon as the GLOW PLUGS light goes off, IMMEDIATELY turn the
ignition key to START. When the engine starts, let go of the key. (The
longer you wait to start after the light goes off, the harder it will be to
start the engine.)
NOTICE:
Holding your key in START for longer than 15 seconds at a time
will cause your battery to be drained much sooner. And the
excessive heat can damage your starter motor.
3. If the engine does not start after 15 seconds of cranking, turn the
ignition key to OFF. Wait one minute for the starter to cool, then try the
same steps again.
If you're trying to start your engine after you've run out of fuel, follow the
steps in "Running Out of Fuel" (see "Diesel Fuel Requirements and Fuel
System" in the Index).
When your engine is cold, let it run for a few minutes before you move your
vehicle. This lets oil pressure build up. Your engine will sound louder when
it's cold.
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