battery isolator switches are usually put on the negative lead which comes of the battery depending on what age of machine you have the this could be positioned in the front of the grill or in the battery box or just below the front of the cab.you basically split the the lead or buy 2 new seperate negative leads, one connects to the battery negative then on to one terminal of the isolator the other then connects on to the other terminal on the isolator and would go to where it was b4.all you do then is insert the key and turn it to complete the circuit to isolate simply remove the key.hope this helps
bally, February 2010
