Low Air/Park Break Audible Warning Failure

[gary rv]

In our 2000 CC Intrigue: While parked with the ignition on or when starting the coach with low air pressure, I do not get any audible warning that the park break is engaged or that a low air pressure condition exists (when low air pressure is indicated on the gauge).

All of the lights (front, rear and park break lights) in the annunciator section of the dash are illuminated as per normal, so I know that the pressure switches in the driver compartment bay are functioning.

I have removed the clamshell cover over the dash instruments and have easy access to the small Radio Shack horn. When I test the conductors to the horn with the ignition on, I get nothing. If I turn the ignition switch off, and then back on with my test leads in place, I get a momentary 12.7 volt reading then nothing, with no horn function.

Any ideas out there? Maybe replace the horn and see what happens?

[TR4]

My coach has no audible warning, only the lights. I also wondered if my coach had this audible warning, but wasn't working.

I'll be interested in what others post.

Bill

[dons2346]

I don't recall getting a audible low air pressure alarm

[CarlAda]

I get an audible until the air pressure is up.

[deandec]

To my recollection, which is often faulty, we have never had the audible alarm.

Since I started doing the DOT pre-trip air brake test about 10 years ago, I have never heard the alarm.

[gary rv]

I could be mistaken, but I thought both audible and visual low air warnings were required by law, for vehicles equipped with air brakes. I know my old coach (98 CC Intrigue) had both, but the audible warning on this coach has not worked since we purchased it last July. I am headed out to my shop now to replace the 12V pizeo horn that I just purchased from a closing Radio Shack store, for $0.97. I figured at that price it was worth changing, just to see what happens...

[gary rv]

OK, so I did do some research on the interweb, and discovered that the law requires either a visual or audible warning and both is an option, but apparently not required.

So what is the existing piezo horn for?

Turns out that the horn is wired in series with the stop engine light (should have checked the single lines first, I guess). But in any event, we do not have a horn on the park break indicator light circuit.

So the question now becomes, do we want one? Thinking through the advantage/disadvantage list, an audible warning might be nice, but possibly a little annoying if a guy were running the engine for any length of time while parked. On the other hand, lights have been known to fail, and even though we have replaced most of our annunciator lights with LED's, an audible warning would come in handy under a light failure circumstance.

If we suffer a catastrophic brake air line failure, the park break should begin to apply whenever the pressure drops below a specified point and we would surely know it, light or no light (and, as it turns out, horn). But one could be caught unawares without a light and/or horn and would be doing some serious juggling trying to figure what the heck was going on.

So what do you think? Adding a horn would take about 5 minutes and I could then surely justify the $0.97 expenditure. But is it really necessary?

Too many choices...arrghhh.

[gary rv]

So, this is what we did.

Turns out, the $0.97 piezo horns were such a bargain that I couldn't resist having a spare so, I bought two...one to use, one for spare parts.

After (over)thinking the pros and cons of an audible alarm, I got to asking myself just what alarm would be of value. I thought that front and rear brake pressure alarms would be of greater value than park brake alarm, since the normal functioning of the park brake would be self evident, either in normal or emergency mode.

So I used both of my new bargain horns, one each, on the front/rear brake low pressure alarms. Now, when pressure in the front or rear system is low, I get both visual and audible alarms, which I think would be good I we were to suffer a failure underway. The horn will get your attention, even if the light won't (which in some normal daylight conditions could go unnoticed).

The wiring is a little different, since the pressure switches work by closing the ground circuit, but it's no hill for a climber.

All in all, I think it was a worthwhile modification to the on-board safety/warning system(s).

[TR4]

Thanks for posting back. When I first purchased my coach I didn't even know I had low pressure lights until I read the entire Owners manual. Apparently both low pressure switches were bad so I never saw the low pressure lights illuminated. I was also thinking about an audible warning. But if the pressure switch goes out, the lights and the audible warning would not work.

I'm interested in how you got around this.

Bill

[gary rv]

Bill -

I think the only way a guy would know that the pressure switch had failed would be when starting the coach in an actual low pressure situation, and not having a visual low pressure warning light illuminate, as you described.

The way the switches are supposed to work, I think, should cause a switch failure to illuminate the light (fail to ground)...but maybe not in all failure scenarios, such as a stuck switch. The switches (and lights) are always hot and only transmit power to illuminate the light when the ground circuit is made.

Many of the lights in the annunciator panel portion of our dash were inoperative when we took possession in July '16, including the step light. This was a real problem because the steps were not fully retracting. All of our annunciator bulbs, except ABS system bulbs, have now been replaced with LED's and the steps repaired, so all is well.

My only complaint with the LED's is that the two amber engine lights glow faintly all the time and light up the world when actually on (before start up), which is a small price to pay.

Oops, sorry, off topic...