GMC 1994 Yukon Owner's Manual page 209

5. Check that the jumper cables don't have loose or missing insulation. If
they do, you could get a shock. The vehicles could be damaged, too.
Before you connect the cables, here are some basic things you should
know. Positive
(+)
will go to positive
(+)
and negative
(-)
will go to
negative (-)
or
a
metal engine part. Don't connect
(+)
to
(-)
or you'll
get a short that would damage the battery and maybe other parts, too.
I
A
CAUTION:
Fans or oeher moving engine parts can injure you badly. Keep
your hands away from moving parts once the engines are
running.
5-5