I have searched our resource guide and the forum topics and have not come up with the procedure of replacing the dash brake valve (has the truck parking and trailer parking brakes, yellow and red knobs). Mine is definitely leaking. I think from the trailer brake valve. Are these valves repairable or only replaceable. Has anyone took one apart to replace the o rings? I came up with a volvo part number 85112212. I have a 2001 volvo which I think would be a gen I . Which is the best way to remove the valve. The volvo valve is kinda pricey. Like around 250.00 , is there an aftermarket valve that is a replacement for this valve.