R Model Brake Light Troubles

[BUDD5670]

Ive been experiencing brake light troubles on my 79 R. The lights work when I hold the pedal on hard for a long time, but not when I just set my foot on the treadle lightly. I put in a new pressure switch, it worked good for a while with light foot pressure, then quit again making me have to stand on the pedal to get the lights to come on. There's always power at live side of switch, its not intermittent, all wires look clean. Brake light switch is a newer deal so i took it apart and nothing inside, no dirt etc. Put it back on and the lights came on with light foot pressure again for as long as they feel like. Go to a show or drive, and soon enough I gotta stand on them again to make them come on. The lights work with the Trolley Valve like a snap. Anybody go through this before?

[peterj]

If they work right with the hand valve, but not the foot valve... your double check valve is sticking/bad.

Where it is located on a R model , I don't know. On many old trucks, the stoplight switch screws into the check valve.

Good luck!

[peelermack]

I just installed a new brake light switch yesterday on my '69 R 600. I had the opposite problem, mash brake pedal brake lights come on, release pedal, brake lights stay on. This truck hasn't pulled trailer in years. My dad suspected problems in the valve assembly that feeds the air hoses for the trailer. We sprayed WD-40 down inside both sides of the valve (where the trailer air lines screw in) and sure enough, now the brake lights operate properly. My switch is located at the pedal valve (don't know the proper name)and was not the easiest thing to change out. Thanks to the board members for the switch part #.