GMC 2002 Sierra - Manual (Page 331)

5-4
2. If you have a vehicle with a diesel engine with two
batteries (or more), you should know before you
begin that, especially in cold weather, you may not
be able to get enough power from a single battery in
another vehicle to start your diesel engine.
If your vehicle has more than one battery, use the
battery that’s closer to the starter
-- this will reduce
electrical resistance.
3. Get the vehicles close enough so the jumper cables
can reach, but be sure the vehicles aren’t touching
each other. If they are, it could cause a ground
connection you don’t want. You wouldn’t be able to
start your vehicle, and the bad grounding could
damage the electrical systems.
To avoid the possibility of the vehicles rolling, set
the parking brake firmly on both vehicles involved
in the jump start procedure. Put an automatic
transmission in PARK (P) or a manual transmission
in NEUTRAL before setting the parking brake. If
you have a four
- wheel - drive vehicle, be sure the
transfer case is in a drive gear not in NEUTRAL.
NOTICE:
If you leave your radio on, it could be badly
damaged. The repairs wouldn’t be covered by
your warranty.
4. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or accessory power outlets. Turn off the radio
and all lamps that aren’t needed. This will avoid
sparks and help save both batteries. And it could
save your radio!