GMC 2005 T-Series Owner's Manual page 195

9. Connect the other end
of the negative (−)
cable at least 18 inches
(45 cm) away from
the dead battery, but
not near engine
parts that move. The
electrical connection is
just as good there,
and the chance
of sparks getting back
to the battery is
much less.
10. Now start the vehicle with the good batteries and
run the engine for a while. If your vehicle has the
high idle option, use it.
11. Try to start the vehicle that had the dead batteries.
If it will not start after a few tries, it probably needs
service.
5-45