Continuing on Truck #1 ( M35A2 ) with no brake light, I pulled out the 2 wire electrical connector that attaches to the switch on the air pack ( conductor # 75, and 75. I depressed the brake pedal leaning a "B" acetylene tank over the pedal,and used my ohm meter sound device to determine continuity. NO circuit! ( see TM9-2320-209-20-2-1 page 25-120 ) Then according to TM9-2320-209-20-2-1, near the same page iit shows how to check the turn signal device, it used my sound devicce and checked for continuity on terminal C, D, AND E. Not there ! So the diagnosis is a bad turn signal device . I also jumpered the corresponding female terminals for ports C, D, AND E on the turn signal control female plug The brake light came on, one side at at time c corresponding to the jumpering. I wonder if I open the turn signal device ifI can fix it?