GMC Envoy Owner's Manual page 386

Notice: If you leave your radio or other accessories
on during the jump starting procedure, they could
be damaged. The repairs would not be covered
by your warranty. Always turn off your radio and
other accessories when jump starting your vehicle.
3. Turn off the ignition on both vehicles. Unplug
unnecessary accessories plugged into the cigarette
lighter or the accessory power outlets (if equipped).
Turn off the radio and all lamps that are not
needed. This will avoid sparks and help to save
both batteries. And it could save the radio!
4. Open both hoods and locate the batteries. Find the
positive (+) and negative (−) terminals on each
battery. Your vehicle has a remote negative (−) jump
starting terminal. You should always use this
remote terminal instead of the terminal on the
battery. The remote negative (−) terminal is located
on the front engine lift bracket on vehicles with
the L6 engine or the engine accessory drive bracket
for vehicles with the V8 engine, and is marked
GND. See Engine Compartment Overview on
page 5-12 for more information on location.
CAUTION:
{
Using a match near a battery can cause battery
gas to explode. People have been hurt doing
this, and some have been blinded. Use a
flashlight if you need more light.
Be sure the battery has enough water. You do
not need to add water to the battery installed
in your new vehicle. But if a battery has filler
caps, be sure the right amount of fluid is there.
If it is low, add water to take care of that first.
If you do not, explosive gas could be present.
Battery fluid contains acid that can burn you.
Do not get it on you. If you accidentally get it
in your eyes or on your skin, flush the place
with water and get medical help immediately.
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