GMC 1999 Sierra 1500 Pickup Owner's Manual page 249

Good Battery
Dead Battery
K2506
10. Now start the vehicle with the good battery and run the engine for
11.
Try to start the vehicle with the dead battery.
awhile.
If it won't start after a few tries, it probably needs service.
12. Remove the cables in reverse order to prevent electrical shorting.
Take care that they don't touch each other or any other metal.
REMOVE CABLES IN THIS ORDER
5-7