whitetailfreak Report post Posted March 28, 2013 I am currently working on a 1989 John Deer Safari 40' motor home with a ford 460 power plant. the engine was remove for rebuilding. Now after reinstalling I am having brake issues with the belt that runs the brake pump breaking during driving. I have noticed the electronic motor that is somehow tied to the brake pump is not working and can not find any information on wiring, switching or any other operation. Help...its ready for the road but can't be stopped. Share this post Link to post Share on other sites
dickandlois Report post Posted March 28, 2013 White Tail, Welcome to FMCA !!! I have a copy of the chassis service manual for your coach, but it is over 900 pages long. So here is a link to the manual in PDF form if you have enough internet bandwidth to download it. The real bummer is they do not separate the Different model chassis. Brake system starts at Page 669. There is an early model and a later model listed as ON / VOY (Carburetor) covered on pages 679 and 680 are drawing covering the different brake plumbing used. I'm not sure what motor you are referring to as no motor is pictured or listed in the manual. http://www.cdr-roc.com/89JD/89-JD-Chassis-manual.pdf#page=62&zoom=auto,0,714 Well, I have to eat my words regarding an electric motor on the John Deere Chassis, Referred to as HYDRO-MAX POWER BRAKE BOOSTER The information on the system starts at page 720 of the manual and covers how the system works. DESCRIPTION AND OPERATIONThe Hydro-Max power brake system is composed of a hydraulic-powered booster (F), mini-master cylinder ( , reservesystem electric pump motor (I), relay (H), electricmonitor and a warning system.During system operation, normal flow from the engine drivenhydraulic pump passes through the steering gear, enters theinlet port (E) of the booster, flows through the poppet valveand booster then the flow switch © and exits from the retumport (D) and returns to the reservoir then back to the brakePump.Force applied to the pedal rod by the vehicle operator activatesthe booster. The resulting pressure in the booster appliesa force to the master cylinder.A pressure regulating valve inside the booster limits themaximum internal booster pressure developed during a fullapplication.Fluid flow through the flow switch "opens the reserve motorpump electrical circuit during normal operation. A separate check valve in the motor pump prevents backflowthrough the motor pump during normal power applications.In the event normal fluid flow from the engine driven hydraulicpump is interrupted, the electric motor pump provides thepower for reserve stops. Upon flow intemption, the integralflow switch "closes" energizing a power relay, thereby providingelectrical power to the motor pump.During reserve operation, fluid is retained within the boosterby an inlet port check valve. The motor pump recirculatesfluid within the booster assembly with pressure built on demandvia the poppet valve. The number of applications islimited only by the electrical capacity of the vehicle.Manual braking is also available in the event both the powerand reserve systems are inoperative.Stopping distances and pedal efforts during a manual brakeapplication are significantly increased. The vehicle shouldnot be driven except for emergency removal from the roadway. SYSTEM CHECKOUT1. With the engine off, depress the brake pedal. The electricmotor pump should run and the warning lamp should belighted.2. Start the engine and push the brake pedal several times.The electric motor pump should not run and the warninglamp should not be lighted.3. Stop the engine, check the reservoir and add fluid asneeded. Regarding the broken belt, I would check the check valves that are mentioned to make sure they are not installed backwards putting undue pressure on the hydraulic system. White Tail, I sent you a private message with a picture of a brake set up that I think you are talking about. Rich. Share this post Link to post Share on other sites