This is something I have been slowly working on to find why my brake light don't work, when I was putting our Chevelle together I added 4 whl disc brakes along with a Wilwood adj. proportioning valve that has 2 prongs for the warning light, my 68 only has 1 wire coming from the new harness same as original, Wilwood says to run a 12 volt wire from battery to one prong and the dash light wire to the other, I was curious if this was why my brake lights didn't work, maybe some type of brake in the circuit by leaving the Tan wire disconnected? so I ran a temp wire with a 5 amp fuse on it to 1 side of the P valve and another 5 amp fused wire to the Tan wire and still no brake lights and No voltage to the meter when pushing the brake pedal so I'm sure when the fluid is low it will make a contact to light the dash light but nothing to do with the brake lights, just a little info in case anyone should ever wonder.