So I know its the RWAL causing me problems. How to i bypass it?

 

Not exactly sure, I was having trouble with the '92 W150 I used to own, and I seem to remember unhooking the electric "brain" behind the glove box. I left the control under the truck and it worked fine. Just no ABS.

 

most cars have a fuse that runs just the ABS. I'm not sure on that truck but thats what I would look at and just pull the fuse if so.

 

Splice in a piece of brake line around the valve on the rear left frame rail
to hydraulically bypass the valve, then go behind the glove box and unplug the controller so the anti-lock light stays off.

 

Does the ABS really do much when it is working?

 

Seems to be a love / hate relationship.

Unplug it behind the glovebox and the light goes out but you are stuck with what ever condition the dude is in.

Someone posted the NAPA #s to bypass the box over the rear axle to remove the whole effect. Not sure if it is in the sticky now or not.

I got the parts but not the time...

 

Dean, what kinda problems are you having with it?

I know alot of guys get touchy about " critisizing" their mods, but you realy need to think hard about disconnecting safety equipment....
Should you be involved in a severe enough accident that they investigated your vehicle condition( normal in fatalites or lawsuits) and it was discovered you had by-passed a "major" saftey feature such as your anti-lock, it could put you in a very bad spot liability wise.... and I am speaking as a past accident investigator who has testified and given dispositons in fatality investigations/suits

The parts for the RWAL arent that much, and are available, so by-passing or disconnecting them is something you realy need to give some thought to if this is a vehicle your gonna be driving on the roads.....


flame-suit on.....go ahead guys, I'm braced and ready...

 

I know the chrysler engineer over on TDR, that used to hang out there, called them the "anti-stop valve" instead of the ABS valve lol Said it was common practice for him to remove them.

If you break hose is long enough to reach it looks like you can just move it back so that it attaches to the line going into the valve instead of hooking the two hardlines together.

Andy

 

If your ABS valve is in the "dump" position and you unhook the brain box in the cab it wont make a bit of difference. You have to either fix the control valve on the rear framerail or bypass it. I bypassed mine using the fittings which I believe are in the sticky. Took about 30 min including bleeding, all you need is a couple of wrenches. It is crazy how easy it is to lock the rear now. I would recommend fixing instead of bypassing RWAL in snow and ice country!

 

anyone have the part # to get a new rwal valve...and what kind of issues are you guys having?? not trying to hijack but

My w250 has all new everthing except hard lines and ralw , was bled till i was blue in the face and my pedal goes down real slow ...about 3" before It give resistance everything is adjusted right, no air, and I did bleed it properly.it acks like fluid doent flow out of the master fast enough or like drums aren't adjusted tight ..(they are) and if i push for all im worth i dont feel the ABS system even trying . my other trucks have fast pedal responce once i get pedal it stops but getting there is slow

 

The problems i'm having is crappy brakes, i think the valve is junk. does anyone have a part number on where i could get one. I went to AutoZone, advance auto, and napa and they all were like "huh" when i asked for one. That is the only reason I wanted to bypass it is because no one knows what I'm talking about.

 

Rebal,

You are describing the symptoms I had. My RWAL valve was stuck in the "dump" or "open" position, basically releasing any hydralic pressure I could build. The truck would stop, but not like it should. I couldn't figure out how to get the valve unstuck so I bypassed. I am not saying bypassing is the best solution, as it makes the truck a little unpredictable in wet, icy, snowy, muddy conditions. It definetaly suprised me when it turned sideways on the first application of the brakes!!

But hey, remember when trucks didn't have any ABS. Somehow, some people managed to drive them sensibly!

I think a non-ABS system is better than a malfunctioning ABS system. That said, I wish my 90 had working ABS, but i will get by without it.

 

I would always recommend fixing the ABS as a first choice. Like JMD says above, it will go sideways in a heartbeat on slippery stuff, and always at the worst possible time, plus you won't be able to get the maximum braking out of the fronts because the rears will be in lock long before the fronts on an unloaded truck. That said, if you absolutely must disconnect the ABS it would go a long towards good drivability by installing a manually adjustable proportioning valve in the rear brake circuit. When you're running light, adjust it so that the fronts lock slightly ahead of the rears and you're safe. When running heavy, crank it up to get more out of the rears.

One easy thing to check and fix on these is a build up of shavings on the ABS sensor in the diff. The sensor is on the top of the diff, comes out with one bolt. Wipe the shavings off and put it back in. Disconnect the battery for a couple minutes to reset the computer and take it for a drive. This fixed mine when it had the same problem you described (long pedal which pumps up).

 

There are salvage yards filled with those parts at reasonable prices.
I know for many "Dealer" is a cuss word, but they do have correct parts avaliable. It is difficult to fix without information provided in a FSM. It is amazing how much diagnostic aid is in FSM.

 

My FSM says RWAL is not servicable..that said we know most stuff can be