I'd read the earlier threads but perhaps misinterpreted the reasoning. I guess my frustration is that I've never owned a tow vehicle in 30 years of towing that required different coding or different expensive adapters just to hook up different types of trailers. And I'd already called etrailer.com the other day to ask about the VW adapter and they said it would not solve the problem for the BMW, though it sounds like for nom3rcy it worked fine.

JCL- My first thought was to check the ground so I used my jumper cables to connect the tongue of the trailer to the hitch, and no difference. But thanks for the input.

I've got a pair of ballast resistors that I picked up online earlier this week, came yesterday. Haven't had a chance to install them, it's just to darn cold out to play with the trailer lights.

BMW zone service rep was at my dealer today so I drove over to see him. He said he's never heard of the problem but opened a PUMA case with NA to see what they thought. But he did say that my trailer control module was a way old version, and there have been revisions. He wondered if that's one of the things that may have changed. I'll know more late next week.

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'04 E53, 4.4 Sport
'97 E39 528i
'86 911 Carrera, track car
'96 BMW R1100R