Got a little whine

Hey folks, I've been reading all the "whine" threads that came up from a search, but none seem to fit my particular situation.

My son has a 2014 V6 Tacoma with AT. It's started to make a whine noise that changes pitch with the transmission shifts. Could also describe it as synchronized with the engine RPM I suppose, but you can only hear it when above 20mph. We can put the trans in neutral and hit the gas and it does not whine, but drop it back in drive, and the whine returns. Gets to a high pitch right before a shift, then drops to a low pitch after the shift.

I'm thinking the trans fluid probably needs to be changed. It's got 137K miles, and has never had the fluid changed. Anything else that could be causing this whine?

I'll also mention, you can hear it much better from the driver's seat than the passenger side.

 

I have a somewhat similar sound. I have always thought it was the secondary air filter crap. I can only hear mine in 4th gear above 2000 RPM. Another reason to eventually just delete it and put a compressor there. Mine has been present since I've had 20,000 miles though.

 

Haha nice, I thought that might be coming

 

Tell me more about this compressor...

 

I have a 12 and they added a secondary air filtration system. I would like to bypass that completely and mount an ARB single in that location. Pretty common mod for pre secondary air filter trucks. OBA is essential to my eventual want of an air locker in the front. Plus it is just convenient.

 

just a thought, have you ruled out engine pulleys?