Parking brake/springbrake issue

[CoachC]

I can't lower my HWH jacks due to parking brake not engaging I believe. Unfortunately I can't move my vehicle from its storage area as the ground is too soft between my pole barn and driveway where it is parked (outside). (Unusually warm here for Dec so ground isn't frozen)
I do not get the parking brake warning light when I pull the valve but brakes do seem to engage. If I push the knob in and do a low pressure test the knob does pop out to engage parking brake.
I have been searching for previously posted info with a similar problem and ideas for possible fixes without much luck. I am learning a lot in the process though.
HWH does not recognize parking brake engagement and the warning (parking brake) light does not illuminate. I want to get my jacks down for storage and finish putting my MH to bed for the winter.
Any suggestions would be appreciated.
Thank you!
CoachC

[dpinvidic]

Is this a Freightliner chassis?

I think all you really need to do is find the parking brake wire that comes from the pressure switch and ground it so that HWH "Thinks" the PB is on.

Your parking brake actually engages when there is no air pressure (or around 35lbs of pressure) in the brake lines.

Regards,

Dan

[GaryKD]

Hi CoachC,
We have the same coach. The diagnostics you have done is spot on. HWH will not turn on if the parking brake (yellow knob) is not pulled out (engaged). As to why engaging the parking brake does not turn on the brake light I do not know. What I do know is if you go fishing behind the parking brake switch, be very careful. The wires are a rats nest and come off their connection points very easily.

If the front of the coach is lower than the rear, consider using this time to completely empty the fresh water tank. When level the tank does not empty completely. Lower the front or raise the rear and it will empty completely.

[GaryKD]

Hi dpinvidic,
The OP has a Spartan chassis.

[twinboat]

The switch in question is probably right on the control, behind the yellow knob.

Air pressure opens the circuit, turning off the parking brake light.

If it has 1 wire on it, ground it like someone suggested.

Otherwise use a meter or test light to see if it works. Build up the air, push in the yellow button and see if it opens the circuit.

[CoachC]

Thanks for the hints. I'll keep looking. I did look at the switch and did not see any wire connections other than what appears to be lighting. I'll look again. Messed with it a bit today. Pbrake does seem to "creep" a bit. Are there sensors in the rear actuators that would illuminate (or not) the parking brake warning light on the dash? Is that done primarily by switch position?
Thanks again for your suggestions.
CoachC

[twinboat]

Because one section of the rear brake chambers contain powerful springs, removing the air applies the brakes. I have never seen any sensors on them.

Could you better explain the creep you are talking about ?

The MH moving ?

The pressure dropping when parking brake is released ?

[CoachC]

Hello twinboat
Yes, MH moves (very slight) and noise of the brake shoes against drums. I'm talking a fraction of an inch movement and it stops after maybe 1,2 or 3 of these "creeps". MH on very slight incline. Very slight if any noticeable pressure drop on release.
Thanks for asking.

[twinboat]

Low drop in pressure indicates brakes are not out of adjustment so what you are experiencing may be normal.

A test of the parking brake is to roll 10 to 20 feet and pop on the parking brake, without stepping on the pedal. It should stop quickly. If it rolls on, you should get them looked at.

Dry S cam bushings, seized clevis pins and a broken air chamber spring will effect the brakes.

Download "Air Brake 2007" for more info then you will ever need.

[dpinvidic]

Originally Posted by CoachC

Hello twinboat
Yes, MH moves (very slight) and noise of the brake shoes against drums. I'm talking a fraction of an inch movement and it stops after maybe 1,2 or 3 of these "creeps". MH on very slight incline. Very slight if any noticeable pressure drop on release.
Thanks for asking.

This is just slop in the brake shoes. You should see the same thing if you kept your foot on the brake, and went from drive to reverse. In my truck, when I set the PB on a hill, there is a slight forward movement when I let off of the foot brake, and the parking brake takes over...even though they are the same shoes. The difference also comes from PB is rear wheels only and foot brake is all 4 wheels.

There is only two ways for your system to know if the PB is applied.
A mechanical switch on the actual PB valve assembly, or a pressure switch on the parking brake line.brake line.

REMEMBER: There are two air supply circuits. Service brake and parking brake. Look for a pressure switch in the parking brake air line...probably somewhere up front.



Wish I could tell you a easy way of tracing it....does Spartan provide any wiring diagrams??

Dan

[hillboy]

Will the park brake disengage? Problem sounds similar to one I had. Pulled into a campground, stopped...went to pull up and could not move the MH. It would struggle to move and brake drums would shake. Did not try the levelers.
A spring in the spring brake chamber broke and punched a hole in the chamber... air leaked out... Brake locked on. New chamber fixed the problem.
Mobile repair guy fixed it in place. Broken spring blocked the "cageing bolt" from engaging so he had to change both chambers.
I did not know until that time that the spring brake chambers fail with age and use. Had the other change when I got home.
May not be your problem but sounds like it

[CoachC]

Thanks Hillboy,
Yes they do disengage or release. Dan may be on to my issue. A pressure switch on the parking brake line would make sense since I am not getting the parking brake warning light when the spring brake is engaged.
CoachC

[CoachC]

Thanks Dan,
A pressure switch issue would make sense. I've seen schematics somewhere online before. I need to search again.
Cheers.


Rick

[CoachC]

Thanks Gary,
Pretty much have the tank empty but it is a bit nose low now so I'll give that a try.
Appreciate the tip.
Rick