Dodge 2007 Sprinter Owner's Manual page 199

Battery isolating switch*
Switching on the electrical system
4
1 Connector
2 Ground pin
Insert the key into the ignition lock.
Press connector 1 onto ground
pin 2 until you feel it engage and the
lock inhibitor is released.
The connector must be in full contact
with ground pin 2.
Move the red slide up until it engages.
All consumers are reconnected to the
power supply circuit.