Problem with power dropout - LionChief Plus GP38

Is the track clean?   If so.  What do you use to clean track?

The track is clean. Used Lionel track cleaning fluid. Also have cleaned the wheels and the rollers with alcohol. And the engine will do this at different places. I also tried it on a different track (although still Fastrack), and the same thing happened. There is no such problem with any other engines I'm running (including other LionChief engines). So I doubt the problem is the track.

@breezinup posted:

The track is clean. Used Lionel track cleaning fluid. Also have cleaned the wheels and the rollers with alcohol. And the engine will do this at different places. I also tried it on a different track (although still Fastrack), and the same thing happened. There is no such problem with any other engines I'm running (including other LionChief engines). So I doubt the problem is the track.

I was going to say, Check the track joints with an ohm meter after opening the circuit. But, you said no other engine have issues. Check for cold solder joints on the pickup roller and ground wires. Maybe even the PC board for loose plugs.

Thanks for the suggestions, Chris. I guess this qualifies as what Click and Clack used to call their question session - "Stump the Chumps" - given that you were the only one to even respond. The engine has two pickup rollers, so I ruled that out as a source of the problem. You mentioned checking the PC board for loose plugs. Seems that's the default first step, and I should have done it before.

I took off the shell and found nothing loose, no wires out of place, etc., but nonetheless pushed all the molex plugs down for good measure, pushed in the boards, shook the wires and so on. There was no indication anything was loose, but after reattaching the shell and running the engine, the problem appears to have gone away! One of the many mysteries of train electronics, a problem which will probably forever remain a mystery.

I personally think your issue is on the ground side.  There were some early LionChief Plus diesels that had their axles going directly through die-cast drive blocks without long-wearing bearings.  That's not a recipe for longevity OR reliable electrical contact!  If you take the loco apart, try to trace the ground path from the wheels to the board stack.  You might have to scrape away some paint and/or clean thoroughly to ensure continuity on the ground side.  Don't even get me started about rubber tires!

If you have a huge layout, you could wire the offending loco to a dummy unit with a tether.  That's a workaround, but it would guarantee good electrical contact.  Personally I've never had enough layout space or a long enough mainline to warrant doubleheading.  Good luck!