Chevrolet Auto-Park

bjarnold wrote:
My wife and I purchased a 1996 Bounder 28' 454 with only 35k original miles. The coach is clean however it has some issues from sitting. The airbags were replaced along with the sway bar bushings, roof re-coated and the fridge circuit board replaced by the dealer at no charge. One issue I found out about which I believe it's fixed is the Auto-Park. When backing up at low speeds it would engage and lock the brake. I would have to shift it from park/reverse/drive several times to release. Today I cleaned the steering column switch now I can hear the pump run for a few seconds while shifting from park to reverse or park to drive. Going from reverse to drive the pump does not kick on. Is this how it is supposed to operate?.

I think you have a version III AP unit and even though you're very close to a transition year, from the previous version that used the power steering/brake boost pump, instead of being self contained. Having said that and going with this assumption....
Park turns off the pump and releases the fluid pressure, sending the brake into default on, actuated by a heavy spring, contained within.
Ignition on (engine running with a version II) and anywhere out of park, starts the pump and releases the brake. In just a few seconds, this pump will build up the required pressure and keep it there. Might cycle momentarily every so often, but this will probably go unnoticed. Unless you put it in park, pull the yellow knob if you have one (typical of a version III) or shut the ignition off, the pressure will stay up and keep the brake off.
With your reverse intermittent problems, it could be that you do have a version II and one of those pesky cam sws., which require some difficult greasing and are usually modified by putting a momentary sw on the steering column for bypassing it.

If you have the time, you can find the switches for cheaper on eBay.

It seems to be working fine now. Before I could not hear the pump engage anytime I shifted to reverse and after 15-20feet the brakes would lock and the Auto-Park light would illuminate. Then shift into drive to build up some pressure then back to reverse until it did it again. I test drove it and drove in reverse for several hundred feet without a problem after cleaning the switch

The pump should not operate when going from R to D. It should operate when going from P to any other position so it sounds like yours is working the way it should. The most common failure is the leaking of the green pressure switch inside. You can check the fluid to see if it is low and remove the back plate to check inside to see it the pressure switch is leaking. After you talk to Roger let us know how you make out. Roger has helped me several times. The switch is available from a Chevy dealer and is about $50. I have changed this twice and now carry a spare.

Roger Haag is THE GURU on Autopark and has been helping people with this system for decades.

A very helpful guy and will be glad to assist(free):

http://www.rvautopark.com/

When contacting Roger, please provide him with all the facts-- exactly what model chassis you have, exactly what is happening/not happening and exactly what you have checked.

This is kind of strange. So from going from P to D, you go through P, R, D and the pump will work. But if you first actually stay on R and go to D the pump does not kick on?

On my 2005 W24 chassis the pump only runs when shifting from park to either reverse or forward, but not from neutral.My understanding of the system is the pump pressure is what releases the brake

I have a 2002 Safari Trek which is on the P32 Chassis and is very similar to yours, with the exception that the Automatic parking brake pump is moved to just under the drivers left foot so I easily hear it every time it engages (on yours the pump should be mounted next to the actuator under the frame, there is a reservoir mounted by the pump with fluid you need to check). The only time it makes noise is when I shift out of park, there is no sound from the pump when shifting from R to N to D. Having said that I would get the linkage looked at as soon as possible,I know of people who have lost their motorhomes to fires caused by a dragging automatic parking brake.