Consisting Problem

[nodcc4me]

I did the fuse test using a 1A fuse. Ran the current up to 16% and it did not blow. Of course, the Over Current error did not come up either.    Other than an intermittent motor wire short I guess there is nothing left to check, though I'm still not understanding why it only happens when they are linked.

[Alan]

Can't solve what you can't recreate.

Reproduce your steps again from the very beginning. Can you get the warning to reappear at any point? Then can you then repetitively create the warning on demand? What are those conditions?

[nodcc4me]

I went through several scenarios and have come up with the following:


Either loco runs perfectly by itself in both directions.
They run perfectly when linked, but separated.
They run perfectly when linked and connected and both are going in the same direction.
The problem only occurs when linked, and connected in opposite directions. Then either one or both go over current.
There is no apparent electrical connection between them through the couplers.

[Alan]

What happens if you put a freight car between them?

[nodcc4me]

I put a car between them and set the original problem engine as the lead, running in a forward direction. They ran for at least 5 minutes with no errors. Then I reversed them and after about 2 minutes, as I brought them to a halt the problem loco went to overload. At that point I couldn't get it to run at all. Each time I reset it and barely moved the throttle it overloaded.

[Alan]

Do you get same results without the freight car? i.e is the physical connection of locos relevant to the puzzle.

Swap LMs between the locos. Does the problem follow?

If not you might ask:
Certain all internal wiring is away from spinning parts of drivetrain?
No possibility of a swaying bare wire touching at a connector or in wire run?
Truck wires insulated and free of interference?
Foreign fragment of metal moving around? For instance a single strand of a clipped stranded hookup wire in the motor brush area.

[nodcc4me]

I'm going to take a good look at all the wiring on that loco. The fact that the problem is intermittent leads me to think that is where the trouble lies. They do have to be physically connected, with or without a car in between, and they have to be facing opposite directions for the overload to occur. When facing the same direction, no problem. Pretty weird.

[nodcc4me]

I believe I've found the problem. One of the motor wires was rubbing on a flywheel and a tiny spec of bare wire was evidently touching it. I insulated that spot and now they seem to be running together happily. I'll do some more testing to confirm. Alan, thanks so much for all your good advice. 

[Alan]

My pleasure. Enjoyable, like reading a good who-done-it novel with the last chapter missing from the book.