No not to reservoir. Pictures are from a donor 1fz engine and harness in my garage just because I couldn't get a good picture of the actual plug in the engine compartment. I pulled the intake to replace gaskets and clean injectors. Had to disconnect a lot of the wiring harness to remove lower half of intake and now getting a "no start" after putting it back together. Came across this plug while checking connections and can't remember what it went to.Possible to the brake fluid reservoir?