Attention: TDR Forum Junkies 
Lost Trailer/Tow Brake lighting recently, flashers fine, truck lighting both brake and signals fine, traced circuit to make sure brake switch was functional, etc, struggled to find exactly what signal/wire from the brake switch was triggering the TIPM to drive Trailer/Tow Brake Lights. Gave in and brought to dealer to check TIPM for codes and hopefully reset to recover. Tech said programing had change and "combined lighting" was disabled and all was good now, of course I immediately put test light on and found issue not to be resolved, after more waiting Tech showed me on the scanner what he had changed and proceeded to measure for 12v on 7 pin trailer Battery connection, I pointed out the brake light connections he should have been measuring and frustratingly left after paying $120 and basically learning little.
Was fortunate to hook up w/ a Service Specialist group who's business is to support independent service centers w/ difficult problems, we hooked scanner up and confirmed TIPM wasn't seeing brake switch signal, after nearly giving up and ordering TIPM ($$$), we found discrepenies in the wiring diagrams and finally what connection TIPM used for the TT brake function, raised TIPM to measure connection and found connection issue at back of TIPM. The moral of the story is don't just give in and replace the TIPM w/o verifing first, obvious if I had replaced the TIPM I would have thought it resolved the issue! Attached are edited drawings to clarify the circuit as I believe it should reflect?
Was fortunate to hook up w/ a Service Specialist group who's business is to support independent service centers w/ difficult problems, we hooked scanner up and confirmed TIPM wasn't seeing brake switch signal, after nearly giving up and ordering TIPM ($$$), we found discrepenies in the wiring diagrams and finally what connection TIPM used for the TT brake function, raised TIPM to measure connection and found connection issue at back of TIPM. The moral of the story is don't just give in and replace the TIPM w/o verifing first, obvious if I had replaced the TIPM I would have thought it resolved the issue! Attached are edited drawings to clarify the circuit as I believe it should reflect?
