When you program a consist the trailing units are assigned a "direction" of travel with the last unit being given an R for reverse.  This flags the lights and couplers for when you hit the DIR button to switch the consists direction.

www.coilcouplers.com has a nice interactive tutorial on TMCC.

Thanks Chuck.  I have the direction of the non-powered A unit facing "backward" on the lashup.  I am not sure how to program the non-powered A unit from the beginning and I think that is my main issue.  Ay thoughts or good resources showing how to program a non-powered A unit into the Legacy controller?

I am dealing with this same issue on my F7 ABBA. I think he is saying that when building your consist with the "train builder" procedure using the cab 2 unit the engine icon for the last "A" unit should be backward. The actual engine should also be backward also. I am going to try this when I get a chance. Somebody feel free to correct me if I am wrong

This may help.

Sorry to tell you but your F units suffer a factory programing error that won't allow marker lamps to operate correctly when programmed as a lashup. 

I have not heard of a fix to correct the error.

Joe

There are a number of locomotives that have problems in an MU with the marker lights working properly, I have the Conrail SD-80's that don't work properly.  I was told they hard-wired the marker lights to the headlights, so in an MU you can never get them working correctly.

Do the marker lights work properly on the individual engines? i.e. if you hit the reverse button on the powered A unit does the headlight go off and the markers come on?

I don't know about his Chuck, but mine work properly if not in an MU.

I don't have any AA consists with the second a as a dummy, only B units.  On those I did not program the as a consist, I just assigned the same engine ID to both.  The lights and couplers behaved the way they were supposed to.  I don't know if they were wired that way at the factory, aka the "front" headlight and coupler are really the rear?  This was the recommended procedure in the owners manual.

>>>I don't know about his Chuck, but mine work properly if not in an MU<<<

The problem is either in the way the markers are wired or in the programing.  

But, they'll work fine as in a stand alone but not when programmed as a MU..

Amazing, nearly two years after the issue was identified, Lionel is still delivering diesels uncorrected with the same old problem. 

Joe

According to Mike at Lionel, mine are wired into the headlights, which is why they don't behave in an MU.  I haven't verified that, but their behavior matches that wiring scheme, so I suspect he's right.  Obviously, they didn't think of the MU when designing the lighting.

I've considered trying to fix them, but I have to give it some thought, based on the lighting outputs available from the electronics.

Thanks everyone for the input.  Chuck, yes my powered A unt works properly when not in a lashup, all lights work the way they are suppose to.  I have tried to run the AA units just by running the Power A unit and attaching the Non powered A unit as a regular car.  The Power A works like it is suppose to but I lose the uncoupling of the rear/Non-Powered A.  I was hoping I was doing something wrong but it sounds as if there is a flaw within the product itself. 

Did you try assigning the non powered car the same engine id as the powered one?  What is the Lionel product number for the units?

Thanks for the quick response.  I downloaded the manual and it differs from the earlier TMCC F Units.  Those were fairly explicit about assigning the same id number to the units in a consist.  Those also had far fewer features.  Maybe Jon Z will post with a definitive answer.

I am going to try and get a hold of a tech at Lionel tomorrow and see if they can give me some advise on how to get the features working the way they should.  If I find anything out I will post it for all to see.

Thanks for all the advise and input.  RickO I watched the video and I have the dvd with the same info and went through it a few weeks ago.  Great info but still did address the directional lighting issue that i am having, unless I missed it.

I spoke to a person in customer service regarding the lashup of a Power A and NonPower A unit.  The marker lights are not suppose to come on when the two units are in a lashup. She did not know why.  Everything else is now working properly with the lashup and mostly because of the help of you on the forum.  Thanks again for all the great advise, I appreciate it.