Like a bad penny, my F7 is back (20-21357-1) is back. It now runs fine...except the powered A unit's couplers do not respond to commands. I inspected the wires, no issues and as suggested in a post here, I specifically checked "the blue wire crimp" and the connectivity was OK. I checked connectivity of the wires from the coupler to the plugs. OK Also connectivity from front to the rear coupler OK I pulled and reseated the plugs on the PCB. Still nothing. Frankly I can't remember if they ever worked. I suspect they did, but, I don't know. Is there a test I can perform to be sure the couplers are actually working? Like the test you can perform on a smoke motor? Oh, the coupler sounds are OK.
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