Originally Posted by jnclem

I just pulled the cover off the lager unit that is supposed to provide brake, tail and flashers. The bulbs are full sized double filliment 12V bulbs. P21/6CP12V is what I think it says. It looks just like a regular 1157 type bulb. I didn't expect that to be what was in there. I need to hook this thing up to one of my trailers and see if it flashes rapidly with a. Actual light system. Maybe I. Chasing a problem in these hitch covers that is actually a problem in the car's wiring or brain.