1991 Fleetwood on GMC Brake problem

[leftysam]

I have a 1991 Fleetwood with a GMC 454 engine. Problem is the brake light remains on when I go from park and the coach will not move. I have had it at a truck repair and they have replaced the power boost that runs off the steering pump and supplies fluid to the braking system. Any suggestions and is there any way to check the power booster to see if it is faulty?
]Thanks Lefty sam

[Gary RVRoamer]

You have the infamous Chevy P30 chassis and the auto-parking brake is stuck on. Your transmission does not actually have a park position - when you put the lever in PARK it goes to neutral and activates a brake on the drive shaft to hold it in place. Without regular maintenance, the auto-park eventually fails and locks up the drive shaft. I'm surprised you haven't had trouble before this on a 91 coach.

[StevePav]

Quote:

Originally Posted by RV Roamer [Gary] ...Without regular maintenance, the auto-park eventually fails and locks up the drive shaft. I'm surprised you haven't had trouble before this on a 91 coach.

Hi Gary,

I have a 90 Southwind and have the same type of brake (JD chassis) I suppose, it only comes on when in Park. What kind of maintenance does the brake require and is it something I should pay some serious attention to? If it does lock up, is there a way to release it manually to get to a repair shop?

Thanks in advance.

Steve

[Gary RVRoamer]

I've never worked on the Auto Park brake and don't know the details. It is hydraulically operated, so checking and periodically replacing the fluid (Dexron ATF) is one thing. Lubricating the moving mechanical parts is another. I understand there is also a cable that can freeze up or the end can break off.

Basically it is a drum type brake on the driveshaft that is applied by a spring that is always trying to set the brake. A hydraulic system pushes the spring back so you can move. If the hydraulic pump fails to run or build sufficient pressure, you are going to stay in park. Or if the drum brake itself seizes up or resists movement, it will stay either on or off, whichever it was at the time (usually on).

Here is one article on this beast (scan down to 2nd article on page)

2006 Tech and Projects

[StevePav]

Thanks Gary! Great link! Much appreciated!!!

Steve