98 lx Auto 162k
I dont know if this is considered as "normal" or not but, lately while working around the engine bay i noticed this buzzing noise in the engine bay.
Only hear it when key turn to II (on) position. Not starting. Just turn key to ON position.
I was trying to diagnose the idle issue, by unhooking harnesses, when i noticed it.
Its a constant buzzing, not loud if hood is shut.
I narrowed it down to the tranny. That's where the noise is emitting from. Directly under the air box..
I unhook all the sensors i could find on the tranny itself but no change..
As though it's an electrical buzz. Like ground loop buzz. Ground cable is solid and clean. Battery posts are free of corrosion.

No trouble code. No flashing D on cluster. Tranny shift smoothly. No hiccup.

What could it be?

 

Maybe a solenoid is stuck on. Do you have a battery drain? Do you have a multi-meter?

 

No battery drain. Yes I do.
Stuck solenoid, if that was the case would it stop buzzing once I unplug the solenoid harness?
It threw a code for the solenoid when I unplug it. So I don't think it's that..code disappear when I plug it back in..noise still present.

I googled it but nothing shows up similar to my issue. Most result are for buzzing while acceleration, buzzing when removed key from ignition. Doesn't fit my scenario.

 

Post the voltage measurement across the two battery posts.

 

Car off: 12.14v
Car Running: 14.54v

 

The battery charge is low. Have it tested.

 

Load tested not just voltage tested. Most auto parts stores can do so.

 

I went to the local part today and they couldn't test it because their machine was dead. Will try other time. I also notice the battery is 2 yrs old. Sold Jan 2014. Marking on battery, 48 months warranty. Its a Lexus OEM battery the previous owner had replaced at the Lexus dealership where he work. No receipt.