Park Brake Warn lite

[arknphyl]

I have a 2005 Newmar Mountain Aire W/24 W/H. Last year I replaced the J-72 Park Brake Assy on this MH. Now suddenly, the brake warning light and buzzer is coming on, but not always. I drove approx 10 mi, 2 days ago, parked w/ no problem. Then started it to put in storage, Put in Drive, lite and buzzer comes on. checked Park pump pressure. Was 1400 lbs, but pump runs when warn lite is on which tells me pump doesn't know there is 1400 lbs of pressure. Feel transducer is problem. Local WH dealer says transducer is not a serviceable part. Does anyone Know this for sure. Thanks for help

[oemtech]

Email oldusedbear@oemys-performance.com. He is the expert on the J71 and just may know enough about the J72 to help.

[quaterhorse]

oldusedbear has a new email Oldusedbear11@Charter.net

[oemtech]

Yes and if you use the Oemy's one he will still get it!

[FreshAir]

Quote:

Originally Posted by arknphyl I have a 2005 Newmar Mountain Aire W/24 W/H. Last year I replaced the J-72 Park Brake Assy on this MH. Now suddenly, the brake warning light and buzzer is coming on, but not always. I drove approx 10 mi, 2 days ago, parked w/ no problem. Then started it to put in storage, Put in Drive, lite and buzzer comes on. checked Park pump pressure. Was 1400 lbs, but pump runs when warn lite is on which tells me pump doesn't know there is 1400 lbs of pressure. Feel transducer is problem. Local WH dealer says transducer is not a serviceable part. Does anyone Know this for sure. Thanks for help

arknphyl, just curious as to why you replaced your J-72 Assy. last year.
Thank's,
Pat

[arknphyl]

Had to replace because Park Brake was worn out. Probably Original owner lost power or pulled yellow button while travel. 1 time is all it will take. You have to replace entire assy. Hard to find. found 1 on E-Bay$1600 + shipping.

[Ding-a-ling]

Quote:

Originally Posted by arknphyl .......... the brake warning light and buzzer is coming on, but not always. I drove approx 10 mi, 2 days ago, parked w/ no problem. Then started it to put in storage, Put in Drive, lite and buzzer comes on. checked Park pump pressure. Was 1400 lbs, but pump runs when warn lite is on which tells me pump doesn't know there is 1400 lbs of pressure. Feel transducer is problem.

arknphyl,

I had this same problem in Aug. '09 in B.C. after an Alaska trip. After crossing into Washington State went to Brazel's Performance RV Service Center in Centralia. The tech put a pressure gauge in the line and we could not get it to fail. He re-mounted the gauge inside for me to watch incase it happens again. So far, after another 22K miles, it has not recurred. The gauge is doing a good job!! Our conclusion, also, was a transducer problem.

I was in communicatrion with oldusedbear regarding this....... He says the J72 brake has hardly any issues. Anyhow, his expertise is the J71 brake.

Frank F.

[DriVer]

Quote:

Originally Posted by Ding-a-ling He says the J72 brake has hardly any issues. Anyhow, his expertise is the J71 brake..

Frank, That's right. The J72 was designed and implemented by Workhorse engineers. The purpose was to achieve the same fault tolerance and reduce the number of components and increase the reliability. I believe you have seen this 1st hand. The J72 was sunset by model year 2006 when Allison gave WCC a 6 speed transmission with a parking pawl.

[arknphyl]

After farther review, I have realized that I may drive 40 miles, without a problem, but stop for 10min or maybe 30min, then buzzer, warn lite and hyd motor runs on (restart and out of park). will be at least a week before I can get it in to WH Service. then will take at least 2 weeks if preeure transducer is problem. Don' t know if they can get complete hyd unit. help

[arknphyl]

FIXED THE PROBLEM---The problem was the pump would not put out enough pressure. It was pumping about 1375 psi, which was on the edge.(sometimes worked-sometimes didn't). "old used bear" found me a “rare” complete used Hyd Actuator Assy. That helped me to discover the problem with my pump (I 1st thought problem was with Pressure Transducer or Electonic Control Module "Called ECM"). I disassembled my Pump and replaced "o" rings. Now pumps 1450 psi and works great.
If you have a similar problem, 1st thing is get a good 2000 PSI gage. if buzzer and brake light comes on and pump motor continues to run(pump should shut off at approximately 1400 psi) and If, upon placing gage in line at pump, you see there is only about 1400 psi or less(with pump still running) you probably are losing pressure past the "o"rings. Before attempting to disassemble pump be sure you understand, if you are not alert and adept at this type of procedure, you may pay a price. You will have to remove entire assy, possibly by separating from ECM which is under the pump and remove 2 Bolts under pump, rather than 3 bolts behind Assy.