Brake me. My back and brain is broke

[Kursk]

On a 2004 workhorse W22 chassis (2005 Damon Challenger) when I press the brake pedal (without the key in the ignition) the Hydro-Max booster BACKUP PUMP comes on and stays on as long as I keep my foot on the brake (goes to the floor if I keep heavy pressure on it). I have checked the associated relay, the fluid level indicator switch, differential pressure switch and attempted to check the flow switch (can't get to pins will need to make special tool to reach in and check for open/closed circuit). All seems well but still have problem. Brake fluid and power steering levels are fine. No leaks detected at any wheels or in brake resevoir area.

If I disconnect the flow switch, the BACKUP PUMP no longer works and I end up with a very firm brake pedal.

I've worked on this all day...

Any suggestions?

[bsinmich]

If the pedal goes to the floor it sounds like the master cylinder is the culprit. Somehow fluid is going past the piston there and allowing the pedal to go to the floor. If you don't have the power boost on you may not be getting enough pressure to make it happen. Good luck on a crappy brake system.

[RIDE10]

Just a possibility. An ole timer told me to turn the ignition key to acc and let the pump run until the pedal rose to the level you desire. Then turn the key to on but dont start the engine. He said it resets something. I had this trouble twice, the first time they replaced the master cylinder, but I am not sure that was the remedy. Worth a try and very economical
Charlie

[DriVer]

Quote:

Originally Posted by Kursk I've worked on this all day...Any suggestions?

Kursk, I'm sorry that you have been wasting your time to resolve a problem that doesn't exist.

When the key is in the OFF position and you step on the brake pedal. the emergency electric pump motor (eepm) will engage and it will provide pressure to the Hydro-Max until you release the brake pedal.

In the event you loose your ignition and the vehicle stalls for example, all you need to do is step on the brake to stop the vehicle. The "EEPM" is wired constantly hot, so it is expected to work all the time "except" when the engine is running.

When you step on the pedal and it goes to the floor (which is sort of deceiving) what you are feeling is the workings of the Hydro-Max in emergency mode. If I'm lying I'm dying!

Put your vehicle on a moderate grade if you can find one. Place the tranny in Neutral and allow the vehicle to roll forward slightly. Step on the brake and you will stop if the key is in the OFF position or in the ON position as long as the engine isn't running.

At speed it won't be as easy however it is expected that you can scrub off enough speed to come to a controlled stop. Note with the eepm running it does not provide power to the steering gear.

I see this is your first post and I want to bid you welcome to iRV2.com. Please come back and visit often.

[wa8yxm]

I have never held the brakes for any length of time but I think the pump is working normally...... There is a problem somewhere in the brake system though. If you are not up to the job I would strongly suggest professional service.

NOTE: if you can hold on a bit.. Take advantage of the recall

[deputydog]

DriVer is right - that is exactly what it is suppose to do. It does what car power brake systems do when the engine isn't running. They have a can that holds enough pressure for a few stops. The one in your RV will work til the battery quits.

Cheers - DeputyDog

[EngineerMike]

My current & last rig have/had the HydroMax. It works just as DriVer & DDog say. The pedal feels like it is mushing toward the floor. If yours drops like there is no resistance, you have a problem. But if it slowly mushes, that's the minimal backup pump providing some boost to effect a stop when there is no boost from the engine's hydraulic pump. You can do the above tests if you need the comfortable feeling of been-there-before.

More important than that IMO, is to spend some deliberate time memorizing the emergency brake procedure for you rig. If the rig is rolling, either the EB isn't set and should be, or it is set and not working and you have a problem. If the EB process is new or a little foreign, an emergency isn't the right time to have to do some fast thinking, better to do fast reacting. Fast reactions come from familiarity. So I sit in the dirver's seat before an outing, and dry-rehearse the EB proceedure a few times. Sort of like dry fire excercises for bullseye competitors, it builds the reflex you want.

[Kursk]

Thank you all for your replies.

This may all have to do with the current (proposed) brake recall. July 6 2008, on the way back from a six hour trip, and just 1/2 mile from home I was coming down a hill and on application of the brakes the pedal went to the floor, brake and ABS lights came on and warning buzzer went off, instrument cluster message "Brake Failure". The light at the bottom of the hill was red! Fortunately on quick successive brake applications I got pressure and was able to stop (before the light). When I got the rig home I used my scan tool to clear the DTC. I checked every thing out, which included feeling for hot brakes, and once satisfied that everything seemed ok went for a test ride. Every thing was fine until I hit about 7 mph and the ABS light came on again. Everything seemed fine except for the pump running continuously as stated at the begging of this thread. I don't recall ever having this issue before this problem. The ABS light is now on constantly.

I cleaned all the wheel sensors today but haven't run it to see if that makes a diff. Will be going for a long Sunday drive in traffic tomorrow (should make the locals happy) to see if stop and go traffic can get it to act up again.

I haven't been able to identify the ABS system until this afternoon. Thought it was a Meritor WABCO but appears to be a Kelsey-Hayes. Workhorse part number is W0000254 but I believe that's just a generic number for ABS EBCM module. Other numbers on the device include 920254K00027376 from a label on top of unit and AH3325E825ABR from attached pump/pressure unit. I took some picture and will try to post them.

My chassis build date was 1/7/2004

I'm looking for an ABS Scanner that works with my workhorse ABS system. Any suggestions? I'm not pleased with my Actron OBDII scanner. Are the Equus 3150 or 3160 ABS scanner a working alternative for my unit?

Does the Kelsey-Hayes utilize BLINK CODE diagnostics?

[Kursk]

[Kursk]

[Kursk]

[EngineerMike]

I'm not sure if I'm concluding correctly from what you wrote.
"Everything seemed fine except for the pump running continuously as stated at the beginning of this thread"

If that is the 12V pump on the hydromax, and it is running while the coach is ambling 7mph down the road under power, that isn't right. The pump should run only when the coach motor is not, as that is the backup system for stopping the rig if the engine dies. Can you confirm & elaborate on that?

Most ABS lights are sensor issues. Failure of the ABS modulating unit itself are fairly rare, tho they do happen. If your HMax backup pump is running full time that is a problem that needs addressing asap. If the ABS light is stuck on, it is probably a melted, dislodged or fouled sensor (most common causes) and may have started when the pedal went to the floor in conjunction w/overheating brake fluid. You might want to check color of brake fluid at each wheel to see if it got burned, or just bleed the whole system which doesn't take a whole lot longer.

[Kursk]

No, the Hydro-Max booster BACKUP PUMP only comes on when stopped with engine off and key out of the ignition.

I took Bertha (my rig) for a ride yesterday and other than cracking the windshield the only other problem was the ABS light came on again at about 5 mph and is now on continuously. Since the windshield broke I didn't go far so it wasn't a true test of the brakes but for the three miles I did get, they seemed fine.

What color will the burned brake fluid be? Can I just squirt a little out of each wheel into a glass and check color? Thanks.

[bsinmich]

Quote:

Originally Posted by Kursk What color will the burned brake fluid be? Can I just squirt a little out of each wheel into a glass and check color? Thanks.

If you are going to do that much why not do a proper job and flush the brake fluid. Anything other than clear indicates the brake fluid is contaminated. I use Ford brake fluid because it has the highest boiling point of any type 3 fluid. If you have never bled brakes before you should probably have someone with experience assist you. The whole job should take less than 30 minutes.