2006 XRunner intake manifold runner question

Hello,
Looking for info on the.intake flap actuation. I have good vaccum to the vacuum solenoid. I can hear the flap cycle when I apply direct vacuum.
I checked for current at the blue wire and.its good. What is puzzling is there voltage on the white wire also but less. Shame on me I was doing a quick check with a test light only.
I don't have a wiring diagram but I would think the white wire is a switched ground wire from the ECU to energize the valve?
I have also read that it gets power from the tail light circuit ?
I did install l.e.d. lamps in the tail lights.
At about 3k rpm I don't hear the sound change from the engine under full throttle like I used to and a bit of a full power loss.
Truck is all stock.
Whats the word. Can anyone send me a diagram and system description or advise?
Thanks in advance