New MTH F3 Diesel Proto-Couplers not working.

Product number? PS2 3V, PS2 5V, PS3?

While on MTH less critical due to the lower voltage of PS2 and PS3 couplers (since you said under DCS) that track power is less critical, but it still might matter. So how are you powering?

There are known issues with the new MTH F3 couplers. Return it to the store and see if they can quickly do the repair. I shipped mine back to the seller and got it fixed right-on-the-spot in their store. They shipped it back to me the same day. 

@Vernon Barry posted:

Product number? PS2 3V, PS2 5V, PS3?

While on MTH less critical due to the lower voltage of PS2 and PS3 couplers (since you said under DCS) that track power is less critical, but it still might matter. So how are you powering?

I see where you're going with this.  I've tried different voltages and I've tried it with an old Lionel ZW, an NCE 10amp 18volt transformer designed to be used with their DCC system, and an MTH transformer.  I'm starting to think I have a problem with this loco.

Regards,

Joe

If the F-3 only has a forward coupler it may also have switch.  But for PS-3 forward coupler to operate it must sense a rear coupler.  Either a real one, or a resistor simulating one.  AA must be connected to fire front lead A coupler.  G