Determining the Function of a Wire Labeled YEL FEED BRK SW on a 1994 Chevy C/K2500

Question:

I have a 1994 Chevy Silverado PU C2500 8 bed. On the existing harness connection plug to the tail lights there’s a wire folded back and taped, the tag on this wire reads YEL FEED BRK SW what would this be for? Thank You

asked by: Robert C

Expert Reply:

The wire you are referring to is probably the center high mount stop light wire or CHMSL. This wire would be used for a third brake light function for example on a camper shell. You can test it by using a circuit tester like # PTW2993. If the wire shows a signal only when the brakes are pressed, and not when the turn signals are on or flashers are engaged, then it is the CHMSL.

If it does show a signal with the blinkers and flashers then it is a taillight brake light wire that also carries the turn signal function, probably for the driver side. If you connect # 118315 and find a function is missing, that may be the reason. I have included a link to the installation details for this wiring harness below.

expert reply by: Michael H