US21 - UltraStop P32 Park Brake Pressure Switch Upgrade Kit

US21 - UltraStop P32 Park Brake Pressure Switch Upgrade Kit


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Part# US21

This kit Replaces GM Part Numbers:

  • Green Switch (At Pump) GM# 15961566 - Also AC Delco# 15034355 (Rotten Green Switch)
  • Grey Switch (At Actuator) GM# 10218778


  • All P-Chassis 1996-2004 that use an automatic apply parking brake system with an electricly driven hydraulic pump.


  • This kit comes with two replacement pressure switches that replace the two factory "High Failure" Pressure Switches.
  • One is commonly known as the "Rotten Green Switch" that controls the pump.
  • The other switch that is replaced is the Grey colored pressure switch at the actuator that controls the "Auto Park" light on the dash.
  • These pressure switches included in the kit are rated at one million cycles of operation.
  • These are a Lifetime replacement guarantee to the original purchaser.
  • Easy installation and comes with instructions.



Last fall, purchased 2003 P32 on winnebago sightseer. Is there any way to know it the your upgraded switches (US21) were previously installed? Without removing the RGS the only #'s I can see are 9171. ( Kenneth Kirby, 08/16/2021 )

Hi Kenneth,

    If you have our switch kit installed they will be red and brass colored. If they look like this one in any way then they are NOT our switches.

( Support )
The first time the brake failed, I had just purchased and it was completely out of fluid. Filling up the reservoir fixed the problem and the RV moved. I drove it 500 miles home and did not not again until recently. I noticed the fluid had leaked, so refilled it again. The next time it failed, the fuse was blown. Replaced fuse and driving it now to have wheel bearing, etc checked.

My problem is that I am getting ready to drive it from Alabama to Oregon and am concerned about a failure or lockup on the brake. Should I purchase the US21 and have the switches replaced? Do these parts interchange with the current RGS and grey switch?

Please reply as soon as possible or call me at 256-508-3650. Thanks for your help.
( Joan McWilliams, 08/04/2021 )
Hi Joan , if the pressure switch(es) are leaking, then the US21 or the US 22 kits would be recommended to ensure your parking brake doesn't lose the fluid and apply the brakes, and /or  cause the pump to fail due to lack of fluid. The US22 kit includes a new 70 amp relay as well as an upgraded threaded bushing for the pump pressure switch. Both kits are replacements for the current RGS and the grey switch.  ( Support )

This may seem like a silly question, but how obvious is the leaking from the factory switches? I've recently purchased a 1998 Pace Arrow. The autobrake is not working properly. When it is engaged, it holds at first, but after 30 seconds to a minute, it slowly releases pressure. Sooo, obviously, there is a small leak somewhere causing it to loose pressure. I haven't had time to troubleshoot it yet, but I thought I'd ask this question. It would be a relatively easy fix if it's just a leaky pressure switch!
( Gord, 05/13/2021 )
Not a silly  question , the leak would probably be apparent by a stream of fluid or lots of fluid under the switch area, also the auto brake is applied by spring pressure and the hydraulic pump and actuator release the brake. If the brake is not holding the vehicle it would indicate aproblem with the brake assembly , the cable , or the "spring can " part of the actuator, the spring being unlikely unless it is rusted or broken .  ( Support )
I have a 2000 Winnebago Brave 33V on a P32 chassis. I'm having issues with the autopark. I have seen several references to Ultra RV having a pneumatic upgrade kit. If this product is available please send me product info and pricing. Thank you. ( Alex, 10/05/2020 )
There use to be an air operated park brake retro-fit available but it was discontinued when we started offering our upgraded hydraulic park brake switches which eliminates about 90% of the issues folks have with this park brake system. ( Support )
My system works fine but I want to upgrade the system to avoid a problem. Can you tell from my VIN if I have an early or late 1995?

What generation system is mine?

What parts do you recommend be proactively replaced to ensure the system is reliable?

Steve D.
( steven dunsford, 08/01/2017 )


This is a later model 1995 and would definitely benefit from our US21 switch kit. I would actually recommend the US22 kit in your case since it would come with an updated relay and steel bushing adapter for the pump switch. The only other failure prone part at the age of your coach is the actuator which can be replaced with part# W8000504N.

( Support )
Description states lifetime replacement for original purchaser but the instructions in the PDF say there is only a two year warranty. Which is it? ( Richard, 07/04/2016 )


We apologize for the confusion. These DO have a lifetime warranty. We will be changing the instructions to reflect this, thank you for pointing it out!

( Support )

Will us21park brake pressure switch fit this viv number

( Raymond E.Parent, 07/15/2015 )


Yes, your VIN indicates that you have an electric park brake pump so the US21 would be the correct kit to replace both the Rotten Green Switch and grey switch at the actuator.

( Support )

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 The state of California requires that this warning be posted for people purchasing products that reside in California.

WARNING: Products may contain one or more chemicals known in the State of California to cause cancer and/or birth defects or other reproductive harm. For more information, visit

VIN Verification Service Item

This product allows for a VIN verification service.

  • This is a service that we provide free of charge when a part is purchased.
  • When you provide your VIN below we will personally verify your part selection by your VIN before shipment of your order.
  • This helps ensure that this is the correct part for your vehicle.
  • This is not an automatic VIN check, it is done by a parts specialist once order is placed.
  • We can only VIN verify vehicles back to model year 1996, if older we can help but can't guarantee fitment.
  • If you would like to have your part selection verified before purchase please call or email us.

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NOTICE: For orders outside of United States

If you are placing an order to ship outside the United States, Shipping Insurance will be required and added automatically at checkout.


  • $295.65
  • $219.00

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