This is the Hogwarts Express set. I thought I had a short in the track. So just using the DC section, if I place a car on it, the car lights come on and the DC light stays steady. As soon as I put the engine on the track, the DC light starts flashing on and off and the engine moves backwards a couple inches at a time each time the DC light flashes. I'm new to this, please forgive me, any idea what might be going on before I try to contact Lionel? Thanks.

Hi Larry, this is the set I ordered from Amazon: https://www.amazon.com/gp/product/B01N81B8S2/ref=oh_aui_detailpage_o06_s01?ie=UTF8&psc=1

The power supply is an 18v (54 watt) unit, model sw1803000-q04

I googled it and I believe this is the same unit: https://www.special-action.top/lionel-54-watt-wall-pack-transformer-power-supply-for-fastrack-new-54w-p-17204.html

Sorry, I didn't know the terminology, I just meant that I only tested with the section of the track that you plug the power supply into (terminal track, I'm guessing?) to rule out any issues with the rest of the track. And yes, that is the light that flashes when I place the locomotive on it, all other cars work fine, the light stays solid. I was afraid there was probably an issue with the locomotive, I'll call them in the morning. Thanks for your help.