I am at the end of my rope,,,, My 99 e-150 has brake problems that not one shop can diagnose. My right rear drum brake locks up, but not all the time. The entire front and rear system has been replaced, including master cyl and brake booster. The Proportioning valve has been discussed but dismissed because only the right rear locks and not the left. AND, there are not and new or used pro valves available except from Ford at $590. I can’t find a rebuild kit either. Two professional shops sat that the pro valve is the squareish looking block with the brake lines attached and other shops say the valve that looks like a 3/4” socket is the pro valve???? I am capable of pulling valve and replacing o rings?? I read about a reset, is there?? I read about a valve bleeder, ?? I have no dash lights on. Can anyone help.

Up date, brake problems. I installed all new front brakes. Calipers, pads, pistons, and rotors. At same time I installed rear, axels, bearings, seals, drums, shoes, and hardware kits. On a 1000 mile trip, heard rubbing on right rear, like out of round drum. Found nothing. Return 1000 mile trip, same thing. Found nothing , but right rear still rubbing. Everything looked great. Then saw ABS light on dash was on. I had it replaced. Light goes out. Still rubbing on right rear, but now very serious grabbing on right rear. Took to brake shop and had drums turned. A week or two later same right rear grabbing. Took to a new brake specialist. Said, due to bad rear system brake settings, front system is burnt, Toast! Replaced calipers, rotors, pads pistons and master cylinder. Still rear grabbing. Replaced front brake booster, still grabbing. Shop says rear system looks great. The shop says they are stumped. They are now talking ABS, modulator and or Proportioning valve. There is even debate about which is which? Google search shows proportioning valve as two different items. Finally went to Ford. First off they say the proportioning valve is out of stock, and no longer available, however they have a source for one at $594. Ford will not work on my van unless they can start from scratch. @ $114 per hour. This van only has 105, ooo miles abs I am only Owner. I suggested pinched brake line, shop says no? If Proportioning valve controls front to rear, why only right rear? System has been bled several times? Pressure at rear wheels has not yet been checked with a gauge. I am a little confused,,,,,,, mrgarlic

Will this help

Hello Hanky, Go to Google Search. Put in Proportioning valve and you get lots of valves. You get the very same picture of same valve. One says proportioning , one ABS MODULATOR. CALL Ford and ask for Pro valve and they quote $595. There is one that looks like a 9/16 socket and is attached to the master cyl. And one that looks like a brass square sided 4” long with brake lines. And is ata he’d to the brass valve. InPortland Ore, the stupid shops are using both names????? I am 77 and grew up doing all my own mechanical jobs. This has me stumped. To make it worse, shops do not like to work on top of another shops works, I spent another two hours today driving around town. Everything seems fine for a while, then stomp on brakes, you will get quick lock on right rear. Do this a few times, the. Go maybe 5 to 8 mph,”touch” brakes and you are stopped dead in your tracks, again, the right rear grabs. I have no problem buying used, . If you choose, I would love to send you photos by email. Of my valves under hood. mrgarlic@gmail.com. Thanks