GMC 2003 GMT560 T-Series Owner's Manual page 197

Don't let the other end touch anything until the next
step. The other end of the negative (−) cable
doesn't go to the dead battery. It goes to a heavy,
unpainted metal engine part or to the remote
negative (−) terminal on the vehicle with the dead
battery.
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 battery and run
the engine for one or two minutes. If your vehicle
has the high idle option, use it.
11. Try to start the vehicle with the dead battery. If it
won't start after a few tries, it probably needs
service.
Notice: Damage to your vehicle may result from
electrical shorting if jumper cables are removed
incorrectly. To prevent electrical shorting, take care
that the cables don't touch each other or any
other metal. The repairs wouldn't be covered by
your warranty.
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