Lionel Legacy SD70MAC- coupler constantly open/firing

I just  got my legacy SD38 Back from Lionel repair. It took 5 weeks. Lionel did a great repair job.  The SD38 had several issues right out of the box.  I also have the Legacy SD70MAC BNSF MERGER.  Its one of the very best Legacy engines!

@Bruce Spector Undoubtedly I want to keep this SD70mac- the BNsF you mentioned is from the same batch. They all appear VERY well made! I guess I’ll give Lionel repair a shot if the factory reset and lash up don’t work.

ironically, a loco I just returned was an SD38 which had issues with sound.  

Had similar issue on Lionel Legacy CP GP35 produced 10 years ago

the coupler would occasionally open up without command

sent it to Lionel for warranty repair, they found the wiring to the coupler was shorting out

look for exposed wire\ worn insulation making contact with grounded component

Top suspect is indeed a short in the coupler wire.  You want to STOP running this until you resolve this as it is likely to cook the RCMC.  It may have already done that, so I'd box it up and send it to Lionel.

@gunrunnerjohn posted:

Top suspect is indeed a short in the coupler wire.  You want to STOP running this until you resolve this as it is likely to cook the RCMC.  It may have already done that, so I'd box it up and send it to Lionel.

A few years later I did have a RCMC failure, not sure if the coupler wire shorting was factor or the board getting drenched with smoke fluid

@gunrunnerjohn thank you so much for your help and advice!! I appreciate it and will begin my first Lionel return Asap... also, if I ever would have run it since, I would have made sure the 2 molex in the truck were unplugged from the main boards. Disabling and quieting the coupler.

appreciate the help from everyone in this thread. Certainly know my course of action now!