random coupler opening

Beings you’ve replaced everything but the paint on the shell, it’s time to look at other factors that can cause random firing. …..dirty track, arcing, sparking, etc, can cause random coupler firing, …..the oddity can make the system believe it’s seeing a signal to fire,….question is, when the coupler randomly fires open, are you hearing the coupler firing sound as if you commanded it to? ……the other possibility is you may have 2 bad couplers back to back, ….I have had this happen!!….can you confirm the coil is being energized when the random opening occurs??…..that’d be the tell tale of an electrical problem with the system, or a mechanical problem at the coupler itself,…oh, & stop tossing parts at it until you diagnose the issue!….you’ll drive yourself bananas doing that!…

Pat

Pat,

The track is clean,  the opening can occur all over the layout on straight sections and curves.  Tomorrow I will try running without the shell on and the lights out to see if there is any sparking with the coupler opening. 

Thanks,

  Marty

@martind posted:

Pat,

The track is clean,  the opening can occur all over the layout on straight sections and curves.  Tomorrow I will try running without the shell on and the lights out to see if there is any sparking with the coupler opening.

Thanks,

  Marty

Marty, the biggest clue will be do you hear the distinct but faint buzz that says the coil of the coupler has been fired electrically,….turn the sounds off to hear this. Verify it a couple times so you know with authority, and then we’ll be able to help you go down the right diagnostic path.

Pat

Marty, I missed the part in your original post that you unplugged the coupler, but it still opened??……this would lead me to believe you just happen to have a bad coupler mechanically……possibly two, back to back,…..but still, verify that you’re not hearing that distinct buzz of the coil,…..it doesn’t cost anything but time to double check a diag. …….also double check you indeed did unplug the correct connector??….We all make mistakes, ….I’ve chased my tail on diags unplugging the wrong thing!….those that say they havent are lying!….😂😂😂

Pat

Vern,  I think I got the problem.  The 4 pin  connector on the bottom of the rear truck was not firmly seated into the pins.  Once fully seated everything is working properly.   I probably should have started at the back and worked forward with the problem solving.

Thanks for your suggestions

Marty

The problem of random coupler opening reappeared the other day and I started to look at the wires more closely.  On the rear truck,  I found that on the female end one of the 4 pin connector one of the wires had a frayed wire that was  not crimped properly and it was causing a momentary short to one of the coupler pins  I replaced the pins on the wires, put some shrink wrap down as far as I could and plugged it back in, Works fine.  So those who have randomly coupler openings on legacy engines, check those connectors and make sure that there are no frayed wires.

Marty