Buzzing starts when in gear then stops when in park 1999 Chevy venture

Best thing go to www.reliable-store.com they have got books on every vehicle and also how to service/repair it,

service/repair/owner's/maintenance manual with
parts info, fuse box, gear box, PCV, torque specs,coiling, wiring diagrams, electrical diagrams, fuse diagrams, error codes, etc everything
Worth it

shift cable adjusment

Try moving the gear shifter to neutral an seeing if it will start then. Park neutral safety switch possibly

I had a simular problem on a mercedes and it turned out to be a blown blub. Check to see if all your bulbs are ok?

Check if the brake light come on when pressing the brake paddle?, IF brake lights do not come on then replace the brake light switch and the shifter will come out of park.

egr valve can be stuck closed

I would be looking at replacing the wiper motor....the wiper switch is just that, a switch to tell the wiper motor what to do.....most of the wiring is housed internal of the wiper motor such as the park circuit and the speeds........osunds like an internal fault.....replacement would be advised

It sounds like you may have bad shock absorbers. It could also be the anti-sway bars are worn out, or broken. These are 2 components that could cause the problem you're having. Take it to a repair center, & have it put on a lift to see the full view of the undercarriage. That will let you see all the components at the same time.

You may have a missing or damaged rubber mount on the transaxel, also a missing bolt can cause this....

when the trans went into park it most likley broke the small rod that engages park and unless you are a capable mechanic with a repair manual you should leave fixing that to a pro hope this helps you