Issue with parking brake (sensor?)

[Praise Bus]

Hi,
We are new to the forum and new to the RV world. We had a bumper pull for four years and in October 2023 purchased a 2012 Tiffin Allegro Breeze 32BR. The issue we are having now is when you go to level or do the slide outs the parking brake alarm rings and the light flashers on the dash. However the parking brake is engaged and is holding. Thank you.

 

[Gary RV_Wizard]

Sounds like the brake-on sensor isn't reporting the status. Could be the sensor or simply the wire that delivers the signal. The sensor probably just puts +12v on a wire for other subsystems (like jacks & slides) to detect. Typically that sensor is on the backside of the brake push/pull handle on the dash. Tiffin could probably tell you how/where that signal gets read by the jacks & slides.

 

[Kirk]

I agree with Gary that it must be a missing brake signal. The fact that neither work and both alarm tends to make that more probable. If you do not have one, a copy of the owner's manual may be of some help. If you have a volt/ohm meter it should be fairly easy to trace the signal.

 

[Praise Bus]

Thank you. Before I joined I called Tiffin and their answer was they believe it’s a break in the communication, however they sent me the wiring diagram which I don’t know how to read. I have all the owners information. When I checked under the dash I am only seeing and feeling the air line on the back of the brake switch. I do see a couple of sensors underneath the front hood to access the generator. I keep looking for the obvious. Please come back with any other information. Thank you.

 

[John From Detroit]

How does your parking brake work? Is it a foot pedal with a pull lever to release it?

If so does the parking brake indicator on the dash light up?
Answers:
if the light lights look at the top of the parking brake pedal where the bracket is. you should see what is called a PIN switch. this will have (most likely) a single wire leading to it and perhaps a tab where another wire can connect and a loose wire hanging near.. Connect.

If no dash parking brake indicator play with that pin-switch a bit it may need to be replaced but often you can get it to work by playing with it ONE TIME.

The link is an example of a PIN switch. so called because of the PIN with the spring around it the brake pedal arm presses on it when released. Yours may be different.

Other brake systems use different types of sensors.

https://www.autozone.com/brakes-and-traction-control/parking-brake-release-switch/p/duralast-parking-brake-release-switch-sw7605/866807_0_0?cmpid=OSA:US&srsltid=AfmBOooHe1m0q6_aNPd4xgKGHgNu6owfUEAV7Zyk2UQmZqcWNnm6wd8YS5k

 

[Praise Bus]

This is much different. It's air brakes with a Bendix on the dash pull on push off for parking brake. Same that is on an 18 wheeler. I believe it is going to be a simple fix, I am just not finding it. Thank you.

 

[Kirk]

I believe it is going to be a simple fix, I am just not finding it.

It would sound like you have what Gary described above; "typically that sensor is on the backside of the brake push/pull handle on the dash." Have you looked at the back of that unit? You should have something similar to this mounted into the dash.

It should have both electrical and air systems connected.

 

[Praise Bus]

Yes, that is it, but did not see anything electrical to that switch. I will check at some point tomorrow. It's very tight quarters in that area. Thank you.

 

[Kirk]

they sent me the wiring diagram

That is the key to knowing where the indication is created and how it gets to the slide-out & leveling mechanisms. If you would tell us the make and model of the two mechanisms, that might help us be able to tell you where the parking brake setting is detected.

 

[Praise Bus]

The brand on the slide outs are HWH Hydraulic Spacemaker. The brand of the leveling which are air bags is HWH also. I am not finding the model on the air bags.

 

[Gary RV_Wizard]

If there is no electrical connection at the dashboard air valve, then there has to be an air pressure sensor on one of the air lines to sense the loss of air pressure. The park/emergency brake valve works by dumping air pressure from the brake lines, allowing the spring-activated park/emergency brake to automatically apply. The brake applies if the air pressure drops below about 50 psi.

 

[Praise Bus]

My air pressure on both tanks are holding, however I still need to get back under the dash to check if there is any kind of electrical hookup on the pressure switch.

 

[Gary RV_Wizard]

My air pressure on both tanks are holding,

That seems odd - I would expect a substantial drop in at least one tank when the Park/Emergency valve is pulled. But you say the brake applies as expected? The rear brake line pressure must drop for the mechanical brake to apply. Maybe that tank sensor is the one that tells the jacks & slides whether the brake is applied?

 

[Praise Bus]

Okay, will check by the tanks. I did find the sensor under the dash. I could not get a picture of it but I have attached a similar picture of the ones under the front. I did unplug and replug the one under the dash as did the others. The two under the hood and the one under the dash all have the same type of plug and same color wires, black and white. And to correct the pressure dropping, it's a small amount, but even with things shut down the tanks hold and do not continue to go down.

 

[Kirk]

Have you checked for a voltage signal anywhere? Here is a link to an HWH service manual that is for the 310 series systems. I'm only guessing at which version you have.

 

[Praise Bus]

I have not. But when you push the button for the slide or the level, right away it the parking brake alarm continues to sound and the not in park/brake light comes on. I am still leaning towards the park/brake sensor. Is there a way to bypass it as a test? I finely found it to the side a bit with an electrical wire plugged in. Nothing changed when i unplugged it.

 

[Gary RV_Wizard]

To "bypass" it you would have to apply +12v to the wire. Disconnecting it guarantees no signal.

 

[Praise Bus]

I do have power to the hydraulic pump. To bypass the sensor, if I unplug the sensor, since the sensor acts as a switch, should I make a connection between the black and white wire? I realize you normally wouldn’t hook black and white together. Just trying to figure out the bypass. And if that does cause everything to work, that sensor is bad.

 

[Praise Bus]

I just pulled the plug off the back of the sensor under the dash. I tested both white & black wires at the plug. My light tester is lighting on the white wire. Under the hood on the other two sensors I am not getting the same. Does this mean I am getting power to the dash sensor but not out?

 

[Gary RV_Wizard]

Sorry, I don't know enough about your chassis wiring to give a useful answer. And wire color means nothing for a DC circuit - there is no standard color or hot or ground.