Ford Repair: 1996 RABS light and stray voltage in Brake / turn circuit, trailer brake controler, rabs

Question
After installing a flat bed on 96 F250 4x4 351cid. with (LED lights)brake lamps partially illuminated when key on.  Lights function correctly brake, turn, tail, BU... but always slightly on.  also RABS light on dash is now on.  Brakes function but RR will lock on agressive braking.  disconnect LED lights and found 9.4 V in brake lamp circuit any time Key is on. Traced loom back into harness and un pluged brake pedal,master cylinder pressure and level sensor, pulled fuses, unplugged antilock valve on frame rail Rabs light still on and 9.4 volts still present, engine perfromance is also off.  Also disconnected trailer brake controler and park interlock on steering column.  Local ford dealer had no data since truck was now 10 yrs old.  Any help would be greatly appreciated.  

Answer
The antilock brake module is behind the glove box, try disconnecting that module and see if it makes any difference. That is the only place I can see any relation between the stop lights and RABS. Also make sure all the grounds are good, you could be getting a feedback from a bad ground, the circuit will look for the easiest ground, and can ground thru light bulbs if there is nothing else. Assuming the flatbed lights are wired correctly, that is where I would look next. Possibly one of the light grounds is connected to the wrong circuit. Recheck any wiring added or spliced.



Your Ford dealer is giving you incorrect info, the manuals are available at Fords' technician website. for  1996 may be as far back as it goes, but it info is there. I would think they would welcome the work!