18.01.2021

Category: J71 parking brake actuator rebuild

J71 parking brake actuator rebuild

Wolf's Motorhome Modifications. Defeating the Auto Parking Brake welcome to our nightmare.

Auto Park Brake

Remember you can click on a picture for a larger image! I defeated my automatically applied parking brake after it began failing and showed problems in both the pump and actuator. These are very expensive items.

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Other owner's experiences showed the rebuilds will again fail. I still had the pedal applied parking brake in operation. I can use that in place of the automatically applied brake. If I didn't put some sort of alarm system on the brake, I might walk away from the motorhome after putting it in park and forget to apply the pedal parking brake.

j71 parking brake actuator rebuild

For this reason I designed an alarm that reminding me to turn on the pedal applied parking brake. I extended that to alarm should I attempt to drive away with the parking brake still applied. This work is not for you.

When the transmission selector is in "park", the parking brake is applied. The parking brake is a drum brake located on the back of the transmission.

The brake is applied two ways. First, one might press the parking brake pedal. The other way is the dreaded auto parking brake mechanism.

If your motorhome is locked up, welcome to our nightmare!!! Get yourself a service manual. If you don't have a service manual, don't waste everyone's time with dopey questions easily understood by a close reading from the people that brought you your problem. It will pay for itself many times over. For my Chevy P chassis, the operative pages are 5F-1 to 5F Failure comes in two flavors.

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First, something catastrophic happens and the brake is applied stopping the rig. Life sucks.

Chevy P30 Chassis - J71 Auto Park Brake Revision

Another flavor is when pressure is lost in the system and the pump cycles on and off, flashing the auto park brake light. This means your life does not yet suck.

God loves you and has given you a short reprieve. How you use your time is your choice.

j71 parking brake actuator rebuild

Personally, I'd fix the brake. I'd fix it NOW. Flavor two offers a problem.Please see our shipping terms for more information. Hello, I would not recommend buying a new factory pressure switch. RGS stands for rotten green switch.

The factory ones are junk and have a high failure rate. I would recommend doing the US22 kit. Feel free to call in and ask for tech assistance also. We like to make sure people are getting the correct parts for the problem they are having. We can only get you a new actuator. There are rebuild services out there but I can't recommend any as we've never used any of them. A good hydraulic shop should be able to match you up on seals.

The state of California requires that this warning be posted for people purchasing products that reside in California. For more information, visit www. This product allows for a VIN verification service. Take advantage of our current sales!!! We are still shipping within 24 hours of ordering!

Thank you for your support during this time, may God Bless America. Order Shipment Notice:. My old actuator had a bleeder valve you could open to allow trapped air to escape, but the new actuator does not.

Not able to bleed or purge the air from the system. All the recommended manual techniques for bleeding, flushing, and purging do not work worked.

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Power steering freezes up when I take the transmission out of park and place it in neutral, drive, or reverse position. Do you think the new actuator may be defective? Or possibly the wrong actuator for my year model and style motor home? I disconnected and capped off the main supply line leading from the power steering pump to the actuator and took the rv out of park and the power steering works normally, but naturally the parking brake remains engaged because it has no power source to disengage it.Please see our shipping terms for more information.

The state of California requires that this warning be posted for people purchasing products that reside in California. For more information, visit www. This product allows for a VIN verification service. Take advantage of our current sales!!! We are still shipping within 24 hours of ordering! Thank you for your support during this time, may God Bless America.

Order Shipment Notice:. These actuators are proudly made in the USA and tested in house. Machined instead of stamped mounting plate, stainless steel one-piece piston instead of two-piece brass and machined stainless steel end cap instead of mild steel. A less expensive alternative than buying an OEM replacement actuator and spring housing.

We offer a 5 year warranty against manufacturing and workmanship defects. I have a Winnebago Brave with a workhorse chassis and Allison Transmission. When I put transmission to park, it will not hold in forward position. It will hold in reverse, even when I apply the parking brake.

I brought to a repair shop and they couldn't find any info on the part or how to fix it. It is very unsafe to drive as I need to jump out and chock the wheels every time I park.

j71 parking brake actuator rebuild

Please help if you have any advice. Not answered yet. Your Name. This is helpful :. This is a service that we provide free of charge when a part is purchased.Please see our shipping terms for more information. The state of California requires that this warning be posted for people purchasing products that reside in California. For more information, visit www. This product allows for a VIN verification service.

Take advantage of our current sales!!! We are still shipping within 24 hours of ordering! Thank you for your support during this time, may God Bless America. Order Shipment Notice:. These actuators are proudly made in the USA and tested in house. Machined instead of stamped mounting plate, stainless steel one-piece piston instead of two-piece brass and machined stainless steel end cap instead of mild steel. A less expensive alternative than buying an OEM replacement actuator and spring housing.

We offer a 5 year warranty against manufacturing and workmanship defects. 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 yearif 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.

Your VIN should start with "5B" or "1G" - This is not an automatic check, it is performed by a parts specialist in our office once the order is placed. Qty Add to Cart. Add to Wish List Compare this Product. Related Products. Add to Cart. Add to Wish List. Compare this Product.If you want us to d.

Take advantage of our current sales!!! We are still shipping within 24 hours of ordering! Thank you for your support during this time, may God Bless America. Latest Discussions. Customer Comments. Workhorse Diagnostic Assistance Alan Sanders. Workhorse Diagnostic Assistance Chuck. Workhorse Diagnostic Assistance Billy Helm. Workhorse Diagnostic Assistance curtis pemberton. Workhorse Diagnostic Assistance Ernie Brodie. Add to Cart. Add to Wish List.

Compare this Product. SPW - UltraPower 8. This is a new product that we offer as an alternative to the factory new replacement. This is the cylinder on the actuator used from on the Chevrolet and Workhorse P32 Chassis for the automatic parking brake system.

This is an upgraded cyli Read More. Part WUSWe have released a new parking brake pump for the autopark systems.

This new pump is We found many that were sent in for the rebuild service ha Our staff is experienced and helpful for repair shops around the country, or RV o In addition to our normal cluster rebuild service Part R, we can now repair Actia instrument cluster main board failures.This article was not done by me Oemybut I thought it should be made availible for those that have the Autopark feature.

This article is just for information only and if you need help in solving a J71 Autopark problem you need to contact Roger by Email Oldusedbear RVautopark or you can check out his web site www. But, Roger may be able help should you have a problem.

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You may also what to download the J72 pdf document in the download section. Sometimes though, we see something that we don't understand, or maybe even disagree with. Sometimes we think there is simply more to be added. Our following comments are directed towards various viewpoints or information contained in this particular thread, as well as to all of us with an interest in the general subject of auto apply parking brakes.

Everyone who contributes to these discussions is trying to help, and technical disagreements should not be translated into criticism of anyone for their ideas or suggestions. We apologize for the length of the following post, and hope it is found useful. Our comments will hopefully be directed to contents of the thread as they serially appear.

Readers can sort through the entire thread and figure out "who wrote what" if that is of interest to them, but the important thing is to kick around the ideas - - not the authors. The RGS is an interesting at least to me design. The choice of materials, along with pressures and temperature, no doubt doom it to failure at some point. The plastic diaphragms that are exposed to system pressure, are always deformed, hard and brittle in the failed switches we have autopsied. I'm convinced that the ravages of time, temperature, and pressure, along with polymerization of the plastic diaphragms, will almost always account for switch failure.

At time of writing, you can still get a new RGS from Amazon for about thirty bucks. The longer lived and better quality pressure switches are far more expensive from what we hear.

Value of the tradeoff between the lo priced and hi priced ones has got to be up to the coach owner. As a matter of technical interest, the trigger pressures of the RGS are not determined by the plastic diaphragm s in the RGS, but by a steel "oil can" type diaphragm.

The stiffness of this steel diaphragm is what determines the switching pressures.

j71 parking brake actuator rebuild

Our best advice based on experience to this point: Build and install your own Genie Lamp setup. Very inexpensive and can save your bacon. You would not likely care to drive a coach that didn't keep you aware of engine oil pressure or lack thereof, and potential lockup of the parking brake, should be about the next thing below that on your list of concerns.

The Genie Lamp will give you a big improvement in your safety margin in that respect. Pump up your knowledge base on the parking brake system. If your AutoPark is giving you trouble, or you're afraid that it might, we will try to give you some help. The AutoPark Library is basically a collection of information. It consists of factory manuals, drawings, pictures, and papers we've written on various aspects of the system.

We have some great assistance from four other forum members who help me with both general and specific problems. There is additionally a huge contribution made by many other forum members who have sent us all sorts of valuable information. We are particularly anxious to help those who want to do their own repairs. On the other hand, if you are trying to just educate yourself, or prepare to deal with a service outlet, that's OK too.

In either case, we'll do what we can. We would stress that we are in no way trying to compete with commercial repair outlets and have no financial interests in any part of the process. In almost every case, we will need to exchange several emails to complete the diagnosis and repair. I usually check my email several times a day, so we normally respond pretty rapidly. It goes without saying that prompt replies on your part will speed up the process.

Not ALL RV'ers are retired though and we understand that many of you just can't drop everything to work on the motorhome. We surely hope that our information is accurate, but can make no guarantees to that effect.

Simply stated, we will do our best to help those who ask.Further questioning of the customer revealed that the electronic parking brake EPB in the vehicle occasionally failed to release after being engaged overnight.

When the fault occurs, the vehicle can be driven without any brake binding or dragsuggesting the parking brake has released. The symptom had been very intermittent for over 12 months regardless of temperature or driving conditions. However, occasionally the ignition was required to be turned off for over 20 minutes before the parking brake function was restored. During this stress test a chime was emitted from the instrument panel and the Parking Brake Malfunction message appeared.

With the error message displayed, further switching of the parking brake confirmed no operation of the LH parking brake actuator whereas the RH functioned normally. Cycling the ignition restored both parking brake actuators to normal operation. The customer complaint was verified and the Vehicle ID and Specification were confirmed. The Customer Interview highlighted a full-service history, numerous accessories installed, and the recent replacement of the LH parking brake actuator but not the complete calliper assembly.

An initial inspection confirmed correct installation of a new LH rear parking brake actuator, the rear brake linings to be serviceable whilst freely operating, and all visible electrical connections and harness routing under the vehicle to both rear brake calliper to be secure.

Based on the evidence acquired so far, pursuing the parking brake fault codes became the priority. This action revealed that a number of parking brake control units were utilised for these vehicles, each of which could be identified by their part number suffix. For example, parking brake control unit part number 4H0 may contain the suffix F, G, or H. All we know at this stage is that a replacement parking brake control unit should contain an L suffix or later.

Food for thought during the diagnosis but insufficient data to warrant replacement control unit without proof of failure. The Description and Operation material was referenced providing a detailed knowledge of component location and functions. After saving and erasing all the above fault codes, the parking brake was once again stress tested by repeatedly operating the park brake whilst monitoring live data.

Initially both actuators functioned correctly drawing approx. This occurred when releasing the parking brake, not applying. With the fault now present, continual operation of the parking brake confirmed no current flow to the LH parking brake actuator, RH operation was normal. A brief check of the fresh fault codes confirmed the return of:.

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At this stage we can attribute these codes to missing messages from the EPB module as the parking brake malfunction results in communication anomalies generating multiple warnings for the driver. The action plan is predominately governed by accessibility and probability. Based on the fact the LH parking brake actuator is repeatedly indicated as the offender, we need to qualify the actuator circuit. With the fault present on the vehicle, the current flow and voltage supply to both RH and LH parking brake actuators was captured using breakout leads and two current clamps connected to PicoScope.

Below, PicoScope live data confirms there is no voltage supply or current flow to the LH parking brake actuator. However peak inrush current to the RH actuator exceeds 20 A. Given the fault was becoming easier to reproduce, the fault codes were once again erased and the parking brake operated whilst monitoring voltage and current to both actuators.

The theory here was to catch the exact moment the fault appeared and identify what events were taking place in the parking brake circuit. Below I have revised all the input ranges and test lead orientation at both brake actuators to provide a clearer view of voltage and current during EPB operation. Above we have captured one of those rare intermittent glitches which is directly responsible for our EPB fault codes. Closer analysis reveals a number of concerns with the voltage supply and current flow through the LH parking brake actuator.

Looking at the zoomed waveform above we can clearly see excessive noise 41 V peak about the supply voltage to the LH parking brake actuator Channel B red.

W8000504N - J71 Parking Brake Actuator (New)

The effect of such noise results in sporadic induced current flow, a 14 A peak at the point of power off to the LH parking brake actuator during the release function. If we compare Channel B red to Channel D yellownotice how the voltage supply Here the induced current flow at 3.

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Whilst the formation and decay of this current is a clue to the parking failure, it is most certainly a symptom and not a cause. I will cover the phenomena surrounding this current at the end of the case study, post fix. Our Parking brake control module suggests the LH parking brake actuator has a short to battery positive. This can be seen in the time taken for the voltage on Channel B red to fall to zero volts after the parking brake release function has completed.


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