Autopark failure on W24

[cbb]

Purchased a 2007 Gulf Stream Sun Voyager on a W24 chassis last month. Did a shake down trip a couple of weeks ago, stayed 10 miles from storage lot. Anyway, upon returning to the storage facility I got the "Autopark FAILURE message when positioning back in my space. Spoke to Workhorse Tech and I need to have it towed in the AM. My previous RV was a HR Admiral 2000, Ford V-10 so I was very deliberate reading and understanding the Autopark brake system. Any ideas as to what I'm up against? thanks CBB

[cbb]

Purchased a 2007 Gulf Stream Sun Voyager on a W24 chassis last month. Did a shake down trip a couple of weeks ago, stayed 10 miles from storage lot. Anyway, upon returning to the storage facility I got the "Autopark FAILURE message when positioning back in my space. Spoke to Workhorse Tech and I need to have it towed in the AM. My previous RV was a HR Admiral 2000, Ford V-10 so I was very deliberate reading and understanding the Autopark brake system. Any ideas as to what I'm up against? thanks CBB

[wilanddij]

Do a search on "oldusedbear". He has loads of experience with autopark.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by cbb:
Any ideas as to what I'm up against? </div></BLOCKQUOTE>cbb, here is about as much information as I have about the J72 Auto Apply Brake. For more information and wiring schematics, please download the FREE Workhorse Motorhome Chassis Guide from www.workhorse.com. Goto parts and start from there. If you haven't registered on-line for "My Workhorse" please take the time to check it out. On MY Workhorse you can see most all the information that pretains to your motorhome.

J72 AUTOMATIC APPLY PARKING BRAKE

The J72 system incorporates a unique full-circle parking brake. The automatic
electric/hydraulic parking system controls the transmission/propeller shaft mounted parking
brake. This system consists of a pump motor relay, vehicle ignition relay, electric/hydraulic
pump, reservoir, proportional relief solenoid valve, pressure transducer, and an electronic
control module (ECM). The ECM monitors seven inputs from the vehicle and controls the
pump motor relay, auto-park light, park brake warning light, buzzer, proportional valve, and
pressure transducer.

To release the parking brake, push in the park brake switch pull-button and move the shift
lever on the steering column from the park position or select "D"�, "N"� or "R"� on the push
button shift control (optional AllisonTM transmission control). Note both situations must
occur for the brake to release. Once the ECM receives the signals from the transmission and
button contacts, the ECM closes the solenoid valve and closes the pump/motor relay allowing
current to flow to the motor. The pump/motor then supplies fluid to the brake assembly. The
brake assembly includes a friction disc clamped by a piston through force of an internal
spring. The fluid pressure acts on the piston overcoming the spring tension that clamps the
friction disc, releasing the brake. The pump motor will shut off when the transducer reads the
fluid pressure of approximately 1400 psi. The solenoid valve holds pressure in the system while
the brake is in a released state. The ECM monitors system pressure from the pressure
transducer and energizes the pump motor when system pressure drops below approximately
1200 psi.

Putting the shift lever back to park, selecting "P"� on the push button shift control, turning off
the ignition, or pulling the push/pull switch prompts the ECM to de-energize the solenoid
valve dumping fluid back into the reservoir. As the pressure decreases, the spring force clamps
the piston back against the friction disc and applies the park brake.

The "AUTO PARK"� WARNING LAMP turns on when the system pressure is less than 900 psi
and the ECM receives the signal from the transmission.

The PARKING BRAKE WARNING LAMP turns on when system is below 900 PSI and when
the parking brake pull-button is pulled out.

The PARK BRAKE PULL SWITCH is mounted on the instrument panel. This is a manual
activation switch for the park brake. This switch is normally closed, pushed in. The body
manufacturer determines final location of this switch.

The PARK BRAKE PUMP MOTOR RELAY is located above the fuse box on the front
driver's side of the radiator core support. It receives ground from the ECM and acts as the
automatic control circuit for the high voltage current required to run the pump motor. When
the ECM supplies ground to the relay switch, the contacts close to complete the feed circuit to
the pump motor.

The IGNITION RELAY is located next to the park brake pump motor relay on the front
driver's side of the radiator core support. It monitors the vehicle's ignition switch to turn
on/off the supply of the fifteen and forty-five amp fused-lines that the ECM and electric
motor use. If the relay was not present, the ECM would be continually powered since it would
be directly connected to the batteries.

J72 ELECTRICAL-HYDRAULIC ACTUATOR
This unit mounts on the driver's side of the radiator core support and is self-contained/environmentally
sealed.

The AUTO/ELECTRIC/HYDRAULIC ACTUATOR controls the pressure in the park brake system to
either set or release the park brake. The actuator consists of a mounting bracket and the
following components:

The ELECTRONIC CONTROL MODULE or ECM is an analog logic device that monitors the various
vehicle conditions then controls the actuator accordingly. It is the "black box"� mounted underneath
the actuator mounting bracket. It connects to the vehicle via a fourteen pin connector, to the
proportional solenoid valve via a two pin connector, and a pressure transducer via a three pin
connector. The ECM is powered by two different sources. First, it receives power primarily through
a fifteen amp fuse. Secondly, the ECM receives power off of the forty-five amp fused-line that the
pump motor relay also uses. Below is a detail of the pin connections of the ECM as well as the
solenoid valve and pressure transducer.

The PUMP/MOTOR ASSEMBLY consists of an electric motor, geared pump, aluminum port
block, and a semi-transparent fluid reservoir. The port block holds the proportional solenoid
valve and pressure transducer. The pump provides fluid pressure for the system. A pressure
relief valve in the port block limits system pressure to around 1700 psi.

The PROPORTIONAL SOLENOID VALVE controls when fluid can return to the pump
reservoir. When the parking brake is released, the valve is closed to hold pressure in the
system. When the parking brake is applied, the valve opens to allow fluid to return to the
pump reservoir. If the vehicle is at a speed greater than five miles per hour (5mph) and the
pull button is pulled, the valve will remain open for a few moments and then release the
pressure slowly for a gradual apply of the brake. NOTE: The park brake is NOT designed for
dynamic stops; if a dynamic stop occurs see the nearest service center for brake inspection.
The PRESSURE TRANSDUCER monitors the pressure of the system and relays that
information back to the ECM. The critical pressure values are the cut-in and out for the
motor which are 1200 psi and 1400 psi, respectively.

[Nonno]

cbb
You said you got the failure message. Is the brake actually set or did you just get the message on the instrument cluster?

DriVer, if it is set, can't he manually release it and drive it to the service center? If it isn't set, again can't he safely drive? If so maybe the tow truck could follow you and if you have a problem pull over and have him tow you. He'll get paid either way but I'd prefer not to see mine or any MH towed if not necessary.

cbb, I'm not a mechanic so obviously do what makes you feel safe.

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bob Russo:
DriVer, if it is set, can't he manually release it and drive it to the service center? </div></BLOCKQUOTE>I would hope so however if the system isn't making pressure or allowing the parking brake to release these are the times when we've heard of vehicles having their drive shafts pulled and towed to service.

I'm sure that Tom N and our other W24 owners will add a good amount of incite to this thread. I have not had to live with an AAPB.

[Tom N]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by wilanddij:
Do a search on "oldusedbear". He has loads of experience with autopark. </div></BLOCKQUOTE>

I spoke to him last summer and he told me he has no experience with the W24 parking brake.

-Tom

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tom N:
I spoke to him last summer and he told me he has no experience with the W24 parking brake. </div></BLOCKQUOTE>Tom, I thought for sure you would have more to share with cbb regarding the AAPB on the W24 since you are a W24 owner.

[Tom N]

I have had no problems so all I can add is, if you don't hear the hydraulic pump, located under the hood, check the fuses.

-Tom

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Tom N:
I have had no problems so all I can add is, if you don't hear the hydraulic pump, located under the hood, check the fuses. </div></BLOCKQUOTE>

[cbb]

More info to help you help me out. I get the pump activity and the fluid level is in range. The alarm will go off approx 5 seconds from engaging the starter. No warnings after the 5 second alarm.(appears that I could select a gear)

When leaving the campground a couple of weeks ago I was not happy
with the Powergear leveler retraction. Primarly the front right leveler. I don't know if this relates to my Autopark problem. Thanks for the info. CBB

[Tom N]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by DriVer:
Tom, I thought for sure you would have more to share with cbb regarding the AAPB on the W24 since you are a W24 owner. </div></BLOCKQUOTE>

How about a photo of the darn thing.

-Tom

[Steady Eddie]

J72--you are right, oldusedbear has no info on the J72 APB except that it is the replacement for the J71. He knows of them, however. I read a post on here that an Owner or Tow Truck Driver cannot manually release the J72 APB. With the J71 you could get going again by blasting out the clevis pin with a hammer, not so with the J72??

I got a kick out of WCC and DriVer's wordspeak when they talked of the white-knuckle-knot-in-the-stomach "dynamic stop"--when the thing slams on at road speed-- --did you catch that??

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Steady Eddie:
With the J71 you could get going again by blasting out the clevis pin with a hammer, not so with the J72?? </div></BLOCKQUOTE>Steady Eddie, That's true the J72 builds up 1400 psi to release the brake. You'd need a BIG hammer to get that J72 to give up the ghost.

Fortunately for 2008 W24 owners, the J72 is gone since Allison deliverers the 2000 series transmission with a parking pawl. I saw a W24 outside of the plant last June 07 that had a mechanical foot brake.

I believe that the W18 is the only WCC vehicle that uses the J72 at this time due to the GM 4L85e not being able to sustain the weight of the vehicle on the tranny case.