How to operate K-Line F7 (TRAILING UNIT-not bi-modal, not tri-modal) Independently

Your second A unit only has lights and motors, no E-unit of any kind. You would have to put a E-unit in. The problem then would be, you could not operate it as a A-B-A or A-A. The back unit would start forward as the front unit would. Not good. Don

scale rail posted:

Your second A unit only has lights and motors, no E-unit of any kind. You would have to put a E-unit in. The problem then would be, you could not operate it as a A-B-A or A-A. The back unit would start forward as the front unit would. Not good. Don

Put TMCC in the trailing unit and give it its own ID. If you want to run them together create a train ID in the remote and off you go. 

I have a K-line FA Santa Fe A-A(early 2000s) with the tether between the A units. It's been awhile since I've tinkered with it or attempted to run it in anyway besides the usual configuration, but, if I recall correctly, the unit without the ran on its own and had 2 switches underneath-one for direction lock and one for sounds. That unit ran byitself. The unit with the tether had the sound portion and would not run by itself, it did have 2 motors and was lighted, as @scale rail described above..

Agree with above comments. I had all 3 units of my K-line Santa Fe  ABA set apart to troubleshoot bad tethers.  K-line F7s ABA sets came in 4 motor (powered A-A) or 6 motor (powered ABA) versions.  There is a single set of TMCC electronics in the lead A unit with a tether providing DC to the motors in the other unit(s) and headlight control in the trailing A unit.  Despite all 3 units having pickup rollers, all power comes from the 2 rollers on the lead A unit.  The trailing A unit rollers power a small MARS light circuit and the B unit rollers apparently are only there to create extra track noise. They are not wired to anything. 

Remarkably, the single TMCC board can handle 6 motors.  I have pulled ten 21" K-line aluminum passenger cars without a problem, but I was probably tempting fate.  

Bob