Backstory, own a 1986 Toyota Truck. Came to me with the rear line disconnected at the T on the rear axle.

Reconnected this line and attempting to bleed down the brakes now are. The load sensing proportioning valve I believe is cock blocking me from any bleed south of the LSPV.

The good news is the bed is off this truck so everything is super accessible. I'll post a picture in the morning. If anybody has ever messed with this valve please drop me a p.m. with a phone number. I figure the procedure super straightforward once you've done it. Thanks in advance.

LSPV stands for load sensing proportioning valve. I hate it when people post an acronym and then don't tell you what the hell it stands for.

It does seem like a strange critter to me, but Toyotas are very impressive so maybe I'm missing something

It distributes the braking force when the bed is loaded down. With the bed off, it could be directing all the fluid to the front brakes. You could try setting some weight on the frame to lower it and see if it bleeds. They do get plugged up from non-use so a junkyard replacement isn't advised. Plan B would be to just bypass it.

Plan B wouldn't be a smart move. Rear wheel lockup with no load isn't quite the ideal situation when braking hard.......................

I bought a tested used replacement off ebay, looked to be in excellent shape, wasn't much to it, and it had a bleeder valve on it, IIRC , so it was easy

I ended up replacing all brake lines and fuel lines, gas tank, sending unit, fuel pump, etc - even the spare tire carrier assembly, just because I had the bed off and I didn't want to touch it again anytime soon

mine doesn't look like this but here is a new one for $60

https://www.ebay.com/itm/NEW-1984-1991-Toyota-4Runner-Pickup-Rear-Brake-Load-Balance-Sensing-Valve/142655049879?fits=Model%3APickup%7CMake%3AToyota&hash=item2136e75097:g:Fy0AAOSwpspbdavX

here is the one I bought

rear brake valve

I'll go and fetch pictures in a few minutes. I was reading about it some on the Toyota nation folks and some seem to say that by passing the unit with a regulating valve is the best way. Lot of folks actually say put the regulating valve inside the cab and I adjust kind of like you adjust a brake controller for electric brakes. Don't know.

She's a $700 truck so I'm sure there's a boatload of things wrong with her. But she runs strong. I'll post pictures in a bit.









All pics...

https://photos.app.goo.gl/3sUFcGjC5ATqtwYw7

Both of my Toyotas('87 pickup and '98 T-100) have this valve but I've never touched either one.

You might be able to disconnect it from the rear end and lift the arm up to open the valve.

I am thinking that I might use a ratchet strap to pull the bed downward toward the axle to open the valve and therefore be able to bleed everything.

Obviously Toyota thought this was a great idea because they've been using it in all of their truck since the beginning of time. Seems super weird to me but if I had my choice of throwing a Japanese engineer or a General Motors engineer off the bridge... it sure would not be the Toyota guy.

You should replace alla the parts on that truck that are over 6 years old.

I would bet it is rusted up and frozen inside, which is why it won't bleed. I replaced mine on my 1997 Land Cruiser, it was a ball of rust and I had to saw it off, the gas tank blocks access to the bolt heads abd the bolts probably would have broken anyway.

There is always a big debate about this at IH8MUD, lots of guys are pretty cavalier about taking them off and running straight lines or maybe some kind of manually adjustable valve. I am on the side of, the Toyota engeineers probably know more about it than I do, and they think it's a good idea, so I'm not going to disable a major Toyota-designed safety feature on the truck. But lots of guys sneer at me on the forum.

The great news for you is, it's so accessible! Won't be hard at all to change.

Damn...

I don't know if I'd agree to that, but if you have the bed off, I'd certainly look at replacing brake lines that show rust. Whether its a $700 or $7000 truck you don't want brake issues while driving.

I ended up buying a new extra sending unit because it took so long to get one shipped from Malaysia, so I have the one from Malaysia, if anyone reading this needs one, I'd give it to someone if they just cover a few dollars for shipping. Its just going to sit in my garage collecting dust