Mercury 1999 Villager Owner's Manual page 186

Roadside emergencies
Connecting the jumper cables
1. Connect the positive (+) booster cable to the positive (+) terminal of
the discharged battery.
Note: In the illustrations, lightning bolts are used to designate the
assisting (boosting) battery.
2. Connect the other end of the positive (+) cable to the positive (+)
terminal of the assisting battery.
186