GMC 1994 Yukon Owner's Manual page 208

To Jump Start Your Vehicle:
1. Check the other vehicle. It must have a 12-volt battery with a negative
ground system.
NOTICE:
If the other system isn't a 12-volt system with a negative
ground, both vehicles can be damage&
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If you have a diesel engine vehicle 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 on the
passenger side of the vehicle
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this will reduce electrical resistance.
2. Get the vehicles close enough so the jumper cables can reach, but be
sure the vehicle's 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.
You could be injured if the vehicles roll. Set the parking brake firmly
on each vehicle. Put an automatic transmission in "P" (Park) or a
manual transmission in "N" (Neutral). If you have a four-wheel-drive
vehicle, be sure the transfer case is not in "N" (Neutral).
3. Turn off the ignition on both vehicles. Turn off all lights that aren't
needed, and radios. This will avoid sparks and help save both batteries.
And it could save your radio!
NOTICE:
If you leave your radio on, it could be badly damaged. The
repairs wouldn't be covered by your warranty.
4. Open the hoods and locate the batteries. Find the positive (+) and
negative
(-)
terminals on each battery.
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