Workhorse P32 auto park brake

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Henry J Fate

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My auto park brake on my 2001 Workhorse chassis P32 has sprung a bad leak somewhere in the line about half way from the pump (front of vehicle) to the rear of the transmission. It's bad and I need to roll out of my location tomorrow. I have not crawled underneath yet and before I do I wanted to see if anyone has manually temporarily disabled one of these auto park brakes to get rolling. It will not be drivable with the current leak so I will either need to fix it or disabled it. Temporarily disabling will be best for my situation.

Anyone know if I can adjust the brake to an off condition to get rolling in the morning?  Thanks.
 

Mark_K5LXP

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The auto brake is spring actuated 'on'.  Without hydraulic pressure to release it, it's stuck in park unless you can restore normal pump operation, or mechanically disassemble the brake shoe actuator assembly.  Then you won't have any park brake at all and will need to use wheel chocks when you stop.

A common failure is the pressure sensor switches.  Are you sure it isn't one of those leaking?  They can be sourced through auto parts stores.

Mark B.
Albuquerque, NM


 

whokares2

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The RGS switch (rotten green switch) which is inside a box covered by a plate often fails. I always carried a spare.  Very high pressure on it when engine is running and it fails, leaks.
 

Henry J Fate

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I did not get under the vehicle last night due to the weather. The reservoir is about empty. There is a bad leak out near the drum assembly. Could be a line or possibly the actuator. The pump, switch and valves are working properly to the best of my knowledge. There are no leaks at the pump control center.

I will have a look this morning to see what is leaking but it puddled up yesterday and appears to be near or at the actuator. It doesn't look good.

I am aware of the functionality of the auto park system and was hoping I could find someone who may have temporarily disabled it to get rolling. I am scheduled to roll out of my location by 1pm today and cannot over stay. I could add fluid to get me out but it's gona leave a pretty good trail and I don't want to do that and would not make it very far anyway.

It's possible I may be able to make the situation better once I get under the coach and have a look but I was hoping to find a way to disable it if I cannot get it working as designed.
 

Isaac-1

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I know it is possible to do with a pair of open ended wrenches to adjust the slack in the cable by the actuator, I think the wrench size needs to be about 3/4 inch, but have not actually done it.  It is also possible to adjust scale slack at the star wheel accessible through the parking brake drum mounted on the drive shaft, however that is just one more thing to fix later on if you do it that way.  Adjusting the star wheel wrong also leads to the chance of a fire, if the brake is set to still drag at all while the vehicle is in motion.

On a side point my automatic parking brake blew a pin hole in the outside of a radius bend partway between the pump and the actuator a couple of years ago, mine was slow enough that I was able to drive it to a local shop, going through only about a quart of ATF fluid for the brake in 5 miles.  Cost to have a new hard line fabricated and installed was about $600, and the shop owner told me if they had to do that same job again they would have quoted more.

About a year after that the stop switch (mounted at the actuator, not the pump which is at the front of 01+ models) failed and dumped all the fluid on the floor of my shed just after I returned home from a trip.
 

Henry J Fate

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Thanks. I am just now getn ready to have a look. Hopefully I can somehow reduce the leak but if not, I will try adjusting. I have tools on board.

Am I correct in assuming that the brake assembly is not self adjusting?
 

Isaac-1

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That is correct it has a star wheel to make adjustments through a small slot in the brake drum.  I helped a fellow P32 owner adjust his using a fiber optic style inspection camera a few years ago.
 

Henry J Fate

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It looks like the stop switch at the actuator. The switch is soaked and dripping and it dosent look like any other area is leaking.

Who would have one of these switches?
 

Henry J Fate

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Cannot find a part number for the stop switch on the actuator.

Anyone have any knowledge of a part number or a place to buy?
 

SpencerPJ

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I won't pretend to have an answer.  I did Google the following :  2001 Workhorse P32 brake stop switch at the actuator  and found tons of discussions.  I also clicked the 'images' link and saw tons of images.  I saw that people have good luck at GM shops.  Hope this helps.  Good luck.
 

Henry J Fate

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Thanks. I need a part number. Have not been able to find.

Hoping Issac has it.

I will call GM to see if they have a part number.
 

wae

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Henry J Fate said:
Thanks. I need a part number. Have not been able to find.

Hoping Issac has it.

I will call GM to see if they have a part number.

I believe you are looking for:
    GM# 10218778
    Workhorse Part# W8001071
 

Henry J Fate

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No info available from GM using the vin and no info on the auto park brake.

They did say that they may be able to help with a part number. Oh well.

The search continues.
 

Henry J Fate

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Local GM dealer found a switch and will have it by 2pm today. Thanks for the part number Wae. It appears to be the switch I need. As far as I know there is only 2 switches and I had the part number to the rgs pump switch so it should be it. What a relief. I should be able to get the coach close enough to walk over and pick it up at 2 pm.

Thanks for all the help. I will update as I move along.
 

Isaac-1

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Sorry about being late responding, spent my morning in the doctors office doing my every 6 month check up.

When mine failed I replaced it and the Rotten green switch with the Brazel's upgraded switches, so that I will hopefully never have to deal with it again.  https://www.ultrarvproducts.com/US21-UltraStop-P32-Park-Brake-Pressure-Switch-Upgrade-Kit
 

Henry J Fate

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I got the part number from Wae and it appears to be the correct part. I just pulled into a wally world and will browse the store while my exhaust cools down then have a go at it. I don't think air got into the service line so hopefully that won't be an issue.

Thanks for the link. I replaced the rgs 1 year ago and now this one. I will look at the other switches maybe I will order and keep them on board
 

Henry J Fate

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Mission complete. Worse part was dropping the plate to get at the switch. I tried to do it without Taking the plate off but it was too tight and poor access.

The brake works great and no leaks.

My biggest issue when getting underneath this coach to fix something is all the other issues I see that may be a problem soon. Brake lines, hoses, etc. Gota spend more time underneath when nothing is wrong. Yet.

Thanks everyone. Job well done.

Henry.
 
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