Park Brake Air Pressure Valve Alarm

[nodine]

Originally Posted by saucerman

Cole-Parmer no longer manufactors the adjustable 50-150 2 wire switch. They have a set 60# 2 wire switch. Do you think that would be an acceptible sub for the adjustable switch? Thanks, Tim 2007 Camelot

I believe you can use the fixed 60 # pressure switch.

Bob

[zo66]

Originally Posted by nodine

Welcome to irv2. You don't mention what coach you have and it is not in your signature or your profile. It is very helpful if folks know what coach you have.

It sounds like you have a very common problem caused by the Nason pressure switch below the parking brake release. It is so common and happens so frequently that I did a study and wrote a paper on the subject. You might find it interesting so I will post it here.

Bob

Bob,

Thanks so much for sharing the your research. I just printed all 15 pages and will use them to solve the issues with my 2006 Camelot.

I have a new Meritor WABCO parking brake switch on order, and I picked up a heavy duty relay and pigtail base at NAPA this weekend. I'm now working on finding a suitable pressure switch replacement. Saucerman was right, Cole-Parmer no longer manufacturers that switch.

Anybody come up with a suitable replacement? I didn't find the fixed 60 pound model. Anybody have a part number of a suitable replacement?

Jim

[slickest1]

On my Imperial that I had I had to replace a sensor on the front air tank that was causing the low pressure alarm. The difference there was the alarm would not stop wether the park brake was on or off.
Having the air pressure drop to 100 and stay there is not such an issue.It will not build back up until it drops to around 90 lbs. and then the compressor will build it back up. If it continues to drop and cause the compressor to cycle then you have a air leak that needs to be fixed. The cause of that may be when the air dryer purges it doesn't seal back up as fast as it should and allows a little too much air to bleed off. It may be time to service the air dryer.

[twinboat]

Originally Posted by slickest1

The cause of that may be when the air dryer purges it doesn't seal back up as fast as it should and allows a little too much air to bleed off. It may be time to service the air dryer.

When the air dryer purges, the purge valve remains open until the governor signals the compressor to start pumping air again.

The system air is retained by a check valve on the downstream side of the dryer. The purge valve remains open so any last bit of moisture and oil can drain out between cycles.

[zo66]

Originally Posted by saucerman

Cole-Parmer no longer manufactors the adjustable 50-150 2 wire switch. They have a set 60# 2 wire switch. Do you think that would be an acceptible sub for the adjustable switch? Thanks, Tim 2007 Camelot

Hey Tim,

I just realized that you were the original post. In my excitement while reading that others have solved the somewhat common re-occurring parking brake pressure switch issue, I failed to recognize that this is your thread. I apologize, and hope that my question about alternative part numbers didn't side track your timely post.

Jim
2006 Camelot

[saucerman]

You did not waste my time. I enjoy reading more info about the whole system.
Tim 2007 Camelot

[YC1]

Bob, only a few techno geeks like me would read through your report like one would a spy novel.

I went through it quickly the first time and then caught my breath. The second time I was doing my Electronic Tech guise and reading out loud specific areas to confirm to myself I was understanding it.

Wow is an understatement.

Can I sit at your table next week??? I would like to know where your expertise comes from. Seriously, you must have done some tech writing in the past.

I got a bit mystified looking at the hand drawn schematic. I had to surmise that the wires off the relay are paralleled and sent to the coach connector.

Without me digging through my coach schematics is it safe to say there is a an original relay living in the front run panel that could be removed as a temporary fix for the annoying alarm or could the plug be removed from the switch to shut the noise off.

I am asking this for future reference as a quick bypass solution when someone is on the road and about to drive off a cliff.

OR, again being too lazy to look at the diagrams can you offer a simple suggestion like, "disconnect the plug from the switch and then jumper color A to Color B"..


Thanks

[nodine]

Originally Posted by YC1

Bob, only a few techno geeks like me would read through your report like one would a spy novel.

I went through it quickly the first time and then caught my breath. The second time I was doing my Electronic Tech guise and reading out loud specific areas to confirm to myself I was understanding it.

Wow is an understatement.

Can I sit at your table next week??? I would like to know where your expertise comes from. Seriously, you must have done some tech writing in the past.

I got a bit mystified looking at the hand drawn schematic. I had to surmise that the wires off the relay are paralleled and sent to the coach connector.

Without me digging through my coach schematics is it safe to say there is a an original relay living in the front run panel that could be removed as a temporary fix for the annoying alarm or could the plug be removed from the switch to shut the noise off.

I am asking this for future reference as a quick bypass solution when someone is on the road and about to drive off a cliff.

OR, again being too lazy to look at the diagrams can you offer a simple suggestion like, "disconnect the plug from the switch and then jumper color A to Color B"..


Thanks

Myron,

I believe what you are looking for is in the box labeled Monaco 2 in the front run bay. On my coach there are two boxes of fuses and relays below the larger FRB circuit board cover. They are labeled Monaco 1 and Monaco 2. We would have to pull out a schematic to verify what to bypass.

You can sit at my table any time Myron!

As for the technical writing, yes I have quite a bit of experience with that. Spent the last 41 years working in Oak Ridge Tennessee, and no, I don't glow in the dark .

Bob

[zo66]

Originally Posted by saucerman

Cole-Parmer no longer manufactors the adjustable 50-150 2 wire switch. They have a set 60# 2 wire switch. Do you think that would be an acceptible sub for the adjustable switch? Thanks, Tim 2007 Camelot

Hey Tim

Thanks so much for posting this thread. I have a 2006 Camelot that has been suffering from the same symptoms. After reading this thread it all makes sense. Thanks also to Bob Nodine for sharing the research paper.

I found this heavy duty relay kit at NAPA that includes a relay base with 12" long leads which are very helpful when building the "Nodine Harness".

Waiting for the new Cole Parmer switch to arrive on Monday

[RCLImperial]

I took a different route or fix my pressure switch than Nodine did. In my electronics junk box I found a microswitch that was the same form factor as the original one in the original unit. I unscrewed the potted switch from the brass base and machined out the old microswitch. With a bit of cleaning up, I fit the new microswitch into the cavity, soldered the wires onto it and potted the switch up with epoxy. After recalibration just as Nodine did, I installed it. It has been working fine for over 2 years and 15K miles.

My one regret is that I didn’t record the maker of that microswitch.

Being cheap and a retired engineer, I’m always looking for alternatives. That old saying applies: “ an engineer can do for a dollar what any damn fool can do for a hundred”

Dick L. 04 HR IMPERIAL

[zo66]

Originally Posted by zo66

Hey Tim

Thanks so much for posting this thread. I have a 2006 Camelot that has been suffering from the same symptoms. After reading this thread it all makes sense. Thanks also to Bob Nodine for sharing the research paper.Attachment 191695

I found this heavy duty relay kit at NAPA that includes a relay base with 12" long leads which are very helpful when building the "Nodine Harness".

Waiting for the new Cole Parmer switch to arrive on Monday

Just wanted to circle back and thank the OP for sending this timely post, and also Bob Nodine for sharing his detailed solution.

I found an unused factory harness that was coiled up behind the access panel right below the parking brake switch. The harness contained exactly what I needed to complete the Bob Nodine harness. (DC common, and an ignition hot). I traced the circuit back to Fuse #14, a 5 amp circuit labeled
"Jack / Antenna Warning" located in the run bay right below the driver's window. It could not have been any more convenient!

I was able to purchase a corresponding plug from Amazon which was the perfect mate to the factory harness.

This project solved both the leaking parking brake switch, and repaired the failed interlock circuit that prevented the leveling jacks from operating. With Bob's relay in place, the reoccurring issue with the interlock should now be rectified.

Thanks again,

Jim[ATTACH]194797

[YC1]

Just curious.

If the thing has failed can you just unplug it to get along down the highway? I understand it won't alarm and one would need to be extra careful.

Just curious if it must send a ground back to the jack pad or transmission to allow the tranny to go into gear.

[zo66]

Originally Posted by YC1

Just curious.

If the thing has failed can you just unplug it to get along down the highway? I understand it won't alarm and one would need to be extra careful.

Just curious if it must send a ground back to the jack pad or transmission to allow the tranny to go into gear.

In my case, the symptoms were that I could drive the coach as usual. The last two times that I reached the destination and attempted to deploy the leveling jacks, they would not operate. If I remember correctly there would be an indication on the leveling jack control panel that the parking brake was not set. I don't believe the red parking brake light on the dash was coming on either.

After the repair, the red parking brake light on the dash illuminates and the leveling jacks now function as expected.

The information here on iRV2 again has saved me so much time, money, and aggravation!

Thanks again everybody

[YC1]

Thanks Zo66.

It would be easy to then apply the signal to let the jacks down if needed. Just need to figure out which two pins to connect.