2004 Workhorse W20 Brake Failure Warning

[zooki11]

Hey Everyone!

Need some help with my 2004 Brave W20 34D. I got the "Brake Failure" warning and alarm a few weeks ago while just sitting at my house idling. I replaced the brake proportioning switch on the master cylinder. The previous owner had glued it in there! It was extremely dirty, I cleaned a lot of the old dirt and rust that I thought contributed to the warning. Fired it up and it was all fixed, so I thought.

Went out today to wash it and it had the failure again, I pulled the switch back out and cleaned it. Still there. I read on another post if you read 0 ohms you'll get the warning. I was reading 0 ohms. I pulled the switch out and was moving it around and could never get anything other than 0 ohms. I left the switch disconnected and still got the warning, should have been an open circuit and canceled the warning but didn't. I then took it for a test drive and the brakes felt exactly like they have always felt. I've replaced the fluid and bled the brakes about 9 months ago. Without smashing all the dishes in the kitchen I did some pretty hard stops, all 4 brakes are working, no leaks.

Attached is a pic of the warning on the dash and the female end of where the proportioning switch screws into.

I'm stumped, any ideas? Thank you!

[zooki11]

Pictures in case they didn't load.

[creativepart]

Not only didn’t any images load, when, as an administrator here, I look at the inner details of your posts there is no evidence of any images even being attempted to be attached.

Here is how you attach photos to your posts:

https://www.winnieowners.com/forums/...ml#post3773760

Also, if you haven’t done so already try asking for more info on this topic at the Workhouse Chassis forum on IRV2:

https://www.irv2.com/forums/f22/

[zooki11]

Thank you Sir, try number 2.

I've been all over the interwebs trying to figure this out. Will also post on irv2. If anybody has any suggestions I'm all ears.

[Morich]

Thoughts on a subject that I've not been near in 50 years?
I think there is likely to be a much more serious problem than simply the light.
I've forgotten most of what I knew about it but I think the way the light works is that the sensor is set so that the pressure on front and rear sections of the reservoir are equal.
The system is divided, one tank for rear brakes, one for front. Then if the pressure drops on front or rear, the sensor makes contact and lights the light.

A long time back, I worked with a brother to put the sensor in, then bleed brake fluid off one section or the other to get the sensor centered.

But looking at the pictures and mention you make of rust, really makes me wonder how much trouble you have. If you are finding rust inside the reservoir at the master cylinder, there has been way too much water in the fluid for way too long to cause the rust.
What I have seen is the water in the brake fluid is a natural thing for brake fluid to collect and absorb the water. Check the brake fluid can for info on that.

But once the water is in the fluid and passed down to all the brake parts like the wheel cylinders, it will rust the inside shiny surface where the cylinder moves as we brake.
As the cylinder moves the rust then is scraping along the sides and will often score them so that we can no longer keep them from leaking. Minor rust can be buffed off but deep scratches require replacing the wheel cylinders.
Classic car rebuilders can tell you lots more about that!

That leak causes the fluid in front or back of the tank to go down and the sensor is no longer centered, so it turns the light on!

I would first look underneath at each wheel for signs of brake fluid loss. It is often easy to spot as the fluid is often sprayed out in all direction as the wheel turns. If you have one wheel that looks different than the others on the inner side, it most likely is leaking!

For resetting the sensor, I recommend finding a manual for the truck chassis the RV is built on and find the specific method to rest it.
But first, I would want to check the system for lots of larger problems that may have caused the alarm to go on.
Rust at the sensor sounds bad from here!

[zooki11]

Morich!

Thanks for the reply! I checked the fluid level, it was full. I also crawled under the old girl and looked at each brake and looked for any sign of leaks. I didn't see any. I even cracked a brake bleed line to examine the fluid and it looked clean.

The dirty metal debris I was talking about was in reference to the female end of the proportioning valve switch, that is one of the attached pictures. It's my understanding that the little hour glass piece in there that would move the switch is sealed off from the reservoir and fluid in the master cylinder.

My chassis has the foot e brake, would anything in the e brake cause this warning. I have read a few older posts that may suggest it?

I'll be under it again today to check along the frame if there are any signs of leaks I'm still When I drove it yesterday the brakes worked like they always have.

[Morich]

OK! Sounds like you may have a better handle on what's up than I might, as it has been a long time back!
I quite likely misread the issue with the rust. I'm likely to be a bit paranoid on that issue as I did have an old Winnebago which I "rebuilt" for a one time trip from Central US to California and back. We drove lots of mountains of course but made it fine.
Other than some stress of elderly mother in law asking my wife if we had brakes coming down East of Denver! YES, Mom, we've got brakes! Bit of stress building between mother and daughter!

Only to sell it after we got home and meet the new owners after a bit and they asked if we had ever had brake problems! Seems ALL the master and wheel cylinders had to be replaced! UGH? Did we have brakes or were they leaking as we came out of the mountains?

I may have built a totally wrong picture? One of the big advantages of the two section design is that any single leak will leave the front or rear brake fluid level different than the other. That can be the first clue to loo for leaks!
But that whole idea may be different in the "newer" RV you have as my bad apple was more likely from the 70-80's period!

[zooki11]

Guy's,

It turned out be the brake reservoir level sensor. Had this emailed to me. See attachment. Thanks!