Update. The dealer had the "North American Engineer", whoever that is, spend several hours with it yesterday. The official answer is that they wash their hands of if. Either the Tekonsha Prodigy brake controller is at fault, or it's wiring is at fault.

Of course all the controller does is sense the brake lights going on. I called Tekonsha and they burst out laughing.

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All that is necessary for the triumph of evil, is for good men to do nothing. -E. Burke.

'87 BMW 325 race car (NASA SpecE30)
'03 X5

www.Gress.org