Check the ground wire for that column first. The drive transistors usually show signs that they have burned up (melted plastic, scortch marks on the driver board, etc). The most common things are bad connections at the connector or a broken wire in the set. Make sure you check the continuity between items as well. Sometimes the wire will break in the insulation between items (switches, lights, solenoids, etc.). If you just look for a broken wire, you may miss these. The easiest way to check is to put the meter on one end of the chain and go item by item until you find you have lost continuity. Then start from there and work backwards to the previous item. The break or bad connection is usually in that leg.
ken