Brake Failed-05 34 FDDS

[vailbob]

I parked my coach in the middle of of January and was getting it ready for the
summer and turned everything on and turned the key. The gages lights came
on and went off except the brake failed light. I can not find anything that will
tell me what to do to clear it. Does anybody know what I can do to clear it?

vailbob

[EngineerMike]

VB- try cycling your chassis battery switch OFF/ON. this will reboot the Vansco chassis multiplexing modules, and the Actia gauge cluster (the idiot lights, lovingly referred to by Actia as Warning Bank Indicators, are part of the gauge cluster and powered off the same source that runs the computer inside the speedo). That will likely kill whatever is lighting the light.

If it doesn't then let us know and maybe we can give you some more misdirection.

[vailbob]

I did that, but it did not work.

VB

[Dave Fernandez]

Hello and Welcome VB:


I would like to welcome you the Alpine Coach Owners Forum and to IRV2.

When you say “brake failed light” do you mean the ABS system light or low fluid light?

If you could describe that the warning light looks like someone may be able to assist.

[vailbob]

I'll check that in the morning and get back to you.

VB

[vailbob]

The park brake light and the brake fail light are the only lights on.
A warning buzzer goes off at the same time. I have picture, but
can not get it loaded.

VB

[EngineerMike]

According to Actia, "The Service Brake Fail indicator turns on when the HydroMax Flow Switch binary input is low." So if that's the light: There have been some failed switches in the history of the HydroMax. There could also be a failure in the circuit. And of course, there could be a problem w/the flow. So if rebooting doesn't make it magically disappear when you start up the engine, that's where I would head for the next steps.

[vailbob]

Well, I guess it did upload. I will try to do the next one.
/Users/jameswilliams/Pictures/iPhoto Library/Originals/2011/Jun 21, 2011_2/VID00005.MP4
This is a video.

VB

[vailbob]

How do I do that?

VB

[EngineerMike]

VB- the Flow Switch is shown on p.7 of this troubleshooting reference. You will find other files dealing w/your brake system on our ACA Tech Library page as well. On our coaches, the Flow switch harness ground (optional) was not installed, i.e. option not taken, and switch is a one wire switch.

Ordinarily I assume a one wire pressure type switch is a N.O. switch and pressure closes the switch to provide ground "signal" to a circuit. In this case, not sure I can assume that w/the Actia description of the fault "Flow Switch binary input is low" A binary input is 0 or 1, and low is 0, but an analog switch cannot produce a 0 or 1, only contact or no contact. So you will have to probe the switch to see what its doing. If its doing the same thing whether coach is running and steering/brakes seem to be working as it is when the key is OFF, then I'd assume the switch is busted & replace it. Check w/truck service firms who specialize in brake work (there are a few in every large town) for the part, or a Workhorse Authorized Service Center (WH chassis' use the HydroMax brake master cylinder assembly same as Alpines to power their disc brakes). If diagnosing the switch is foreign to you, I'd suggest taking it w/the above info and maybe a printed copy of the diagnostic doc to a truck brake service joint. If figuring out the fircuit's status is w/in your realm of competence, please post your results.

Here is a thread discussing what I think is the same switch w/the gentleman ordering the part & replacing it himself.

[vailbob]

So my son-in-law came by today and we tested the two switches at the MC.
The flow switch seems to be functioning since the backup pump runs when the brake is applied with out the engine running.

The pressure differential switch reads an open circuit both with and without the brake applied. We pulled the switch out and bench tested it and got the same result, and if I read the documentation correct the normal operation of the switch is an open condition and it is only closed if it senses a difference in pressure between the two systems.

Finally I believe I failed to mention that the reason for all this diagnosis is that the coach is currently not running, it seems that the systems never get past the preliminary checks, leaving on the lights I spoke of earlier as well as a warning buzzer, so the engine never has a chance to start.

Any ideas where to go next?

Thanks for all your help with this...
James Williams
vailbob@juno.com

[vailbob]

EM, I had a service man come out and check the Data Port.
He said the the transmission neutal had no power. He jumped
it out and the engine started. I will let you know what happens.

vailbob

[vailbob]

Found ignition wire not making signal to transmission ECU-
bypass wire to start.
Found and located problem,chase out transmission wiring,
fuse connection broken behind fuse block in battery compartment
(wire was pushed out the back)cut wiring and built new fuse holder.

Works fine,
VB

[Rufnek]

VB,

Do you stay in GJ full time?

Don