I am having the same issue with my 96 k 1500. I have replaced both tail light circuits, turn signal switch, brake switch and relay. Pulled the wiring harness all the way to connectors C104, C110, and C111. Inspected that section of harness, and oh I also have this same elusive wire. Mine was taped off at the rear and has power when you press the brake pedal but no other time.
-Take notice the 4 white wires coming from the TCC/stop lamp upper right corner. 2 of those wires have connector C100 A and C104 E as a point where they are running to. Look further down on image 1 and see brown wire going to connector C104 A.
-In image 2 if you look in the center you see yellow going to C104 C and dark green going to C104 D
- Have not found C104 A
- In 3rd image you see backup lamp wire coming from connector C100 C to the rear.
- You will notice in these images that brown, yellow, d green, and l green all run to rear harness connector C409 but the white shows it going to connector C298 F, stop lamp relay B pin and on page 1 to TCC, cruise, and turn hazard switch. Image 4 shows location of C298.
- Also note that C104, 110, & 111 are all listed as being on the rear lamp harness.
White wire is coming from C298 through the I/p connector to C104 and just runs down to the rear. Same length as other wires. White wire through C100 runs to relay switch in under hood fuse box. Now you are where I am with no brake lights. Everything has been replaced and checked. With multimeter and light. White wire acts like it is the rear brake light, and as far as factory goes. There are no splices or nothing out of the ordinary that does not look factory.
Images (Click to make bigger)
Thursday, July 25th, 2019 AT 5:50 AM