Please excuse me is I am in the wrong place for this question, as I am a nube to this forum, but anyways, here goes:
I have an 2000 E450 (might be a '99 frame) with a class C motorhome attached. This thing gets little use, about 1000 miles a year. It was last driven about 4 months ago.
When I started it today, the brake & ABS light are on and stay on. The pedal is spongy (if I hold steady firm pressure, it will creep to the floor). When I start the engine, the lights are on for the normal light check time...then they go out for a split second, then they come back on. This is a new problem as everything was fine when parked, and now the brakes seem to work, just problems as described.
I have tried pulling the fuses, as was suggested elsewhere in this forum...That didn't work.

All suggestions will be welcome. I do understand this stuff....all except the ABS parts (they didn't have that stuff when I stopped turning wrenches).

Thanks for your input.

Bill the nube.

As an electrician I always suggest:
"Its only a shock if you don't expect it"

 

A large number of times the ABS light can be attributed to a wheel sensor having go bad or misreading. However since you are also experiencing the pedal slowly going to the floor, My guess would be a vacuum leak somewhere between the master cylinder and the brakes. Which on a Class C can be some long lines to check.
While your coach is V-10 powered you may also try looking in a few other forums that may be able to steer you more to a brake/mechanical area. One site that comes to mind is RV.Net : RV.Net - The Leading RV Community, Club, RV Travel and Information Source for Recreational Vehicle Camping and go to the Class C forum. Or to one of the more mechanical forums here on this site.
Good Luck
Happy Camping,

 

Had a transmission range sensor/wiring harness problem that contributed to my ABS light issue.

 

Could be lots of things, but the sinking pedal is not a good thing.

Sounds like the ABS unit might be leaking internally, and bleeding off pressure into an accumulator. I don't know why that would happen suddenly though.

Gotta check out the entire brake system, make sure nothing's leaking.

I assume you hit the brake pedal when you went to start it?

Usually, the brake light comes on either when the master cylinder reservoir is low, or the valve that balances the front and back brakes goes all the way over to one side when there is no pressure in one side. Not sure if the ABS unit finding something wrong will light the brake light, but I think so.

Let's work more on this...

 

Thanks for the input, krewat..........I'm trying to find someone where I can take the motorhome and get the codes pulled. I really HATE the local "stealer" as I had lots of trouble with them with a Windstar in the past.
Normally I would just go to an ASE mechanic, however tooling around in a 31' motorhome is a little different than a PU. Most shops around here are tight for space.
The one thing I need to really check again is the brake fluid level sensor. That seems to be a probable cause of the brake light and the installed configuration makes it hard to get to.

Wish me luck.....
Bill

As an electrician I always suggest:
"Its only a shock if you don't expect it"

 

Well, just got back from the mechanic. It appears that the rear VSS is out. I kinda discounted that as a problem as my spedo is working fine...........should have looked for the spedo cable to the trans.
This new (to me) mechanic found the problem, so I'll let him fix it. In this economy we all need the work. He will have the part tomorrow.

Thanks to all
Bill

As an electrician I always suggest:
"Its only a shock if you don't expect it"

 

Ah yes, the old E-series speedo thing...

It's one of the things I've tried to keep in my brain.

Find a V10 w/tranny from an E-series, to transplant into any vehicle. No need for a VSS for the speedo so the PCM can shift right... Because the tranny has an output shaft speed sensor instead of using the VSS for road speed.

 

While it's great the VSS solved the light-on issue, it doesn't address the soft pedal. I would continue to look for brake issues. Stopping these rigs require solid brakes!

 

After driving the rig today, (I actually had not "driven" it, just in the driveway) I think that the soft pedal was just in my imagination. I could get the pedal to drop, but I had to really stand on it for 30 seconds or so. But yes, Monsta, I will pay close attention to the brakes so I don't make the nose of this rig any stubbier than it already is