Hi. I have a 99 f250 that has a buzzing noise coming from the transmission. 4 speed auto Trans, v8, The dtc code function on this truck does not show any codes. But it does have a code saying the dtc obd2 function is not working properly.

It seems to do it when in 1st, 2nd, & drive, when at a stop on brake. But I'm not sure the brake part matters. The Trans is a rebuild but has performed flawless for a long time. This issue is new.

I have the pan off and no apparent issues. Could this be a solenoid going out or getting ready to go out.

It's definitely a buzz. Loud enough to hear inside truck with window down.

Fluid and filter was changed on schedule.