450G John Deere Dozer

Pedals won't pump up after starting machine. I have checked everything possible! Any suggestions?

Do you have two pedals or one brake pedal? I did read the statement with the plural on the word pedal...so I am thinking you have steering controls for your feet.
Sorry this is just for my clarification - the 450G I am familiar with has one big pedal for the brake and one small one for the throttle decel.
Mine steers by levers, but the brake pedal immediately 'pumps up' as soon as the machine goes into gear after moving park lever.

In the trouble shooting section of the deere manual is mentions this... sadly I don't have the manuals anymore nor do I remember what the solution was. incidentally, when you raise the park lock control do the lights go out on the dash and you can move the machine?

I looked into the manual: in the section 9005-10-6, Brake Pedal Upper Stop and Return Spring Check - "....should be able to watch the brake pedal rise to the upper stop....if not go to section 9020-20....." That section begins with Engaging Tow Disconnect Pins Manually (with access by opening floor board). Then there are a lot of sections on brake adjustment. Some section on pressure adjustment.

Didn't really see any words on Pedal Rise when shifting lever out of Park position.

Your 450G sounds to be equipped similarly to my 650G. Dual pedals (foot steer) direct-drive power-shift transmission?

You should be getting a 'STOP' light and loss of hydraulic pressure warning. Is that happening? If so, then the hydraulic pressure for shifting and brakes has not engaged, lost prime, fluid low, etc.

Of course the engagement lever has to be lifted out of 'park/brake', into 'operate' position, as StumpJumper suggested.

If you have lifted the park/brake lever, the steering pedals do not pump up, and you are not getting any fault indications, I'd suspect the warning system was non-functional.

there is a screen where the trans oil goes into the pump , go through the floorboard its on the transmission case, they have been known to collapse or stop up

Anyone ever figure out a fix for this, mine is doing the same thing… will not move…. Pedals will not come up… no warning lights on. Was running dozer and it stopped suddenly.

I copied my response from a 550G thread you posted a similar question on earlier today.
I suspect the transmission suction screen was uncovered for a few seconds and the transmission pump took a big gulp of air. The suction screen is dead center on the lower bottom edge of the transmission front face. I also suspect the transmission pump is in poor condition and is struggling to pull the oil from the transmission case. I suggest loosening off the transmission pump discharge hose ,roll the engine over on the starter and see if the pump will regain its prime. You may have to slightly pressurize the transmission case at the dipstick tube to help shove the oil to the pump.