The brown wire that goes to the brake warning lamp switch is just cut about 2 1/2 inches from the bulkhead connector and a plug is installed there. I see no other explanation than it has something to do with testing that switch, but I cannot find that plug anywhere but in the 73 chassis service manual, which was pointed out by Townsend and where it does say that there is a test plug there. Interesting thing is that I looked all over the 72 and 73 service manual and there is no test in there where you would use that plug...
