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Mr.Geritol · 07-18-2012, 12:21 PM

I have a 1996 Raven on the P30 chassis with a tag axle.Currently redoing the tag axle brakes. On the regulating valve from the chassis brake side there is a pressure switch that I can not figuir out what it does. The park brake warning light comes on when I step on the brakes but the switch on the park brake is working well and adjusted correctly. Just wondering if any of the more experienced RV'rs out there know what this switch does.

Mr.Geritol

Jim_HiTek · 07-18-2012, 03:50 PM

I'm confused...why would your PB light come on when you step on the brakes? It should come on only when you shift into Park.

Perhaps that pressure switch can be tested by just removing the electrical connector...see if a light comes on or goes off at the dash. Where is that switch physically?

mgscott4 · 07-18-2012, 06:39 PM

Is it sensing brake line pressure? Low pressure maybe.

Mr.Geritol · 07-19-2012, 08:45 AM

It is sensing Brake pressure by the look of it. I have worked on many brake systems and never seen a pressure switch at the back.

Mr.Geritol · 07-19-2012, 08:46 AM

I plan on doing that my next trip under. Just got a new master cylinder for the tag break and waiting for wheel cylinder kits.

Mr.Geritol · 07-19-2012, 02:46 PM

Quote:

Originally Posted by Jim_HiTek

I'm confused...why would your PB light come on when you step on the brakes? It should come on only when you shift into Park.

Perhaps that pressure switch can be tested by just removing the electrical connector...see if a light comes on or goes off at the dash. Where is that switch physically?

The switch is in the brake line by the valve which regulates the tag brake booster. I am stumped why it is there. If it serves no purpose it will be gone. Or mayby I will move it to the tag axle side to let me know if the brakes which don't appear to have worked for years are working. I am hoping someone can giove me a logical explanation why it is there.

Mr.Geritol

Jim_HiTek · 07-19-2012, 08:48 PM

I'm pretty sure that it serves a purpose. Just have to figure out what it is.

You are also having a problem with the tag axle brakes. Maybe it has something to do with that? While many pressure switches just activate an idiot light on the dash, others go to a relay or controller and activate some other function.

I'd remove it and replace it, just in case there's some function it's suppose to be doing that it isn't. And of course there are ways to test it. Most I'm familiar with have a P/N on them so it's generally easy to find a replacement since it's a generic part. And they aren't that expensive. JMO.

BTW, you started this thread with "Park Brake Light" and P30s are known for having parking brake issues. Rotten green switch comes to mind. It's hard to figure out what system you're working on.

Here's some info that may help: "The Auto Park lamp goes on when the parking brake is applied, or whenever the pump motor is running.
This warning light has two separate switches, which can cause the light to go ON. One is the pump motor switch - a.k.a. the Rotten Green Switch - and the other one is a pressure switch mounted on the actuator. The Rotten Green Switch (RGS) turns on the Auto Park light at the same time it turns on the pump motor."

Mr.Geritol · 07-20-2012, 12:30 PM

Thanks, Like many other P30 chassis owners I have had the autopark problem. For that I changed the switches and adjusted the cables. For as long as I have owned this rig (4 years) the Park Brake warning light comes on when I apply the brakes. It has never made any sense to me but as all else seemed to work I took it to be a idiosincrecy of the unit. I have found a few other mtc issues with the unit. When I found the tag axle brakes not working that started me on the hunt and where I found this forum with a lot of good comments from some very nice people. Work has draged me away form the task for a bit but when I get back to it I will post here. I thought I would ask if anyone knew if it actualy belongs, my own guess is no It does not.

Mr.Geritol