Pete 389. Parking brake won't release, please help

If you had a couple tools, we all would gladly walk you through isolating the issue and getting you repaired.

 

Take off all the service brake hoses off @ brake chambers on drive axles. Release tractor brakes only and see if air is leaking thru a chamber would be the first step.

 

Most Pete's I have worked on use -8 SAE flare fitting on service side of chamber, so should be 7/8 wrench.

 

Just an FYI for the future (not going to throw any suggestions because @spsauerland is leading you in the right direction). Most all air valves have their exhaust ports open to atmosphere when not actuated. So when an air valve is leaking large amounts of air out the exhaust, chances are its a valve/component up or downstream of the leaking valve that's the culprit. Just passing along to hopefully save someone a few bucks in the future.

 

Be safe out there and keep us posted. A couple decent adjustable wrenches, vise grips, and assortment of brass fittings and caps/plugs/unions is a must among a few supplies that are a must for a truck in my opinion.

 

You got a rubber disk of sorts with a center tab holder. Examine that area if possible very carefully. Im not current on today's modern braking but I can sort of work it in my head to know that particular box is important to everything related to your service brake.