Autopark repair

[TandW]

Last nite Autopark wouldn't let us out of daughter's drive. Hydraulic pump motor had resistance on VOM due to water intrusion which made it difficult to diagnose. Never found the fusible link that chassis guide mentions. Anyway, the motor comes off easy enough. Found water, emulsified lubricant, rust, and loose solder within. The bimetallic thermal overload contacts were actually delaminating, although fused together. Solder appears to have come from brush cage to overload mating point. That's where the 'open' was. Resistance on the 'wet' motor before clean-up and repair about 170 ohms. After repair about 2 ohms. After it was placed back together, system was found to be operated on and off by the motor thermal overload. The so-called rotten green switch won't open on pressure rise. Oh well, it's my turn in the ---rel!!

[TandW]

Last nite Autopark wouldn't let us out of daughter's drive. Hydraulic pump motor had resistance on VOM due to water intrusion which made it difficult to diagnose. Never found the fusible link that chassis guide mentions. Anyway, the motor comes off easy enough. Found water, emulsified lubricant, rust, and loose solder within. The bimetallic thermal overload contacts were actually delaminating, although fused together. Solder appears to have come from brush cage to overload mating point. That's where the 'open' was. Resistance on the 'wet' motor before clean-up and repair about 170 ohms. After repair about 2 ohms. After it was placed back together, system was found to be operated on and off by the motor thermal overload. The so-called rotten green switch won't open on pressure rise. Oh well, it's my turn in the ---rel!!

[oemtech]

Contact Oldusedbear and he will help fix it....

[TandW]

Oehmey, I'll get a switch tomorrow, hopefully, from my NAPA guy, but I'm thinking of converting the proximity switch to the operating switch. Upon destructive disassemly of the rotten green switch it was found to have a membrane that had swelled. This is probably an incompatibility issue with DEXRON III. The switch failed closed which then tore up the pump motor. Not a good thing!! As so many others have commented over and over and over, the AUTOPARK was poorly engineered. But, I will repair it and persevere on. GOOD LUCK!!!

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TandW:
As so many others have commented over and over and over, the AUTOPARK was poorly engineered. But, I will repair it and persevere on. GOOD LUCK!!! </div></BLOCKQUOTE>The J71 system can be challenging however the newer J72 has greatly reduced the complexity of the J71.

I'm sure if anyone can figure this thing out you will Chief.

[TandW]

Driver, it's 2 times now that I've stayed "off the hook". Put another way, you just can't be tellin' the Cap'n that we'll have to anchor out!!

[DriVer]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TandW:
Driver, it's 2 times now that I've stayed "off the hook". Put another way, you just can't be tellin' the Cap'n that we'll have to anchor out!! </div></BLOCKQUOTE>Gonna have to put a BIG "E" on the side of your motorhome.

[tropical36]

This is some of the heaviest of tech. talk, I've seen on the auto park system, except for some of the tech. manuals from oldusedbear ...and re-engineering has me as guilty as there is. Actually the system isn't a bad one if not for the evil switch. The best cure however, would have been a tougher transmission with a parking pawl, leaving no need for thing in the first place.
Back to the RGS...I keep thinking there's a better switch out within the pressure ranges that could be adapted to fit the existing fittings, thereby eliminating this on going problem, since GM and Workhorse obviously don't care about having this failure reputation.
I mean, I almost bought a ford chassis because of this infamous feature alone.
On another note, I must have one of the better J71's, because when my RGS failed, the pump motor kept quitting as with a thermal cutout of sorts, so the pressure never got so great as to rupture the pressure switch (RGS), thereby rapidly depleting the fluid, and creating a lockup.
I probably drove it (not smart) another 100 miles after the light came on, so I could have a campground of my choice to do the repairs.
It's easy enough to replace the switch (DON'T BE CAUGHT WITHOUT A SPARE) as long as you don't mess up....sooooo, if that should happen, it's nice to be in a campground, rather than the side of the road. Again you're taking a chance on having it lock up if you continue on, which opens another can of worms and is another topic of discussion, besides having it towed.

[TandW]

There are a few in this forum who will not condone this, but a limit switch can be affixed to a u-channel which is then affixed to the pivot bolt that holds the relay arm where the cables are enjoined. Adjusting bolts on opposing sides of the u-channel provide for switch adjustment and will impinge onto the pivot bolt mount. The switch is a common momentary, push to close starter switch for panel mount. It will impinge onto the trailing edge of the cable relay arm, which is the forward position as mounted onto the chassis. With coach parked and brake "ON", the switch is depressed and "closed". When brake is released the cable relay arm moves away from switch, thus "opening" the hydro-motor circuit. Of course, the new switch will be wired in series with or jumpered around the "RGS". Your choice! Good luck!!

[tropical36]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">There are a few in this forum who will not condone this, but a limit switch can be affixed to a u-channel which is then affixed to the pivot bolt that holds the relay arm where the cables are enjoined. Adjusting bolts on opposing sides of the u-channel provide for switch adjustment and will impinge onto the pivot bolt mount. The switch is a common momentary, push to close starter switch for panel mount. It will impinge onto the trailing edge of the cable relay arm, which is the forward position as mounted onto the chassis. With coach parked and brake "ON", the switch is depressed and "closed". When brake is released the cable relay arm moves away from switch, thus "opening" the hydro-motor circuit. Of course, the new switch will be wired in series with or jumpered around the "RGS". Your choice! Good luck!! </div></BLOCKQUOTE>
If I'm reading you right, then I have a question...
How is the pump motor supposed to run intermittently, (only an instant at a time) and keep the pressure up during normal bleedoff? Granted, for short runs, it probably wouldn't make a difference, but let's say for instance we're driving day and night non-stop. Wouldn't we eventually not lose enough pressure to start dragging the brake a little at a time and burn them away as we go?
By the way in your OP...wasn't the auto park light on for some time while all this was taking place?

[TandW]

Tropi-Cal. Lastly, no. The other alarm lite did not ever come on when my "RGS" failed closed. My hydro-motor was obviously operating on and off via the internal bi-metallic thermal current limiter. I had a no release condition that pointed out the failure. As for your first question, one may renew the "RGS" and run the new position switch in series with it and the pump relay. Or you operate without the"RGS" with the new position switch alone. If you maintain a working "RGS",along with a new position switch, the new position switch should be adjusted to "open" the circuit before the "RGS" does. Good luck!!

[tropical36]

When my RGS failed, my pump motor cycled on and off the same as you've described, and the ...auto park...light was on also. Steady and without a flicker. I never lost any fluid, so there was no lockup, but if I had continued indefinetley, I sure it would have been ineveitable....and probably sooner, rather than later.
As far as your modification idea goes, it's certainly something for this ex-navy electrician to think about. Have you mentioned this to oldusedbear...our in house...auto park...guru?

[oldusedbear]

Workarounds for the various AutoPark functions and failures are always an interesting topic - - At least for the folks who have, or work on AutoPark systems.

Some folks want only to add a foot pedal or a hand lever to a system which does not have one - - this would include a few units built around 1990, and then most everything from about 99 thru 07. With these versions, you have to get the AutoPark working, or you have no parking brake at all.

Many others have proposed various types of parallel systems or other add-ons to take over if some component fails. Of course, even a setup with reduntant components for EACH function, can still fail, and you are always (ultimately) back to the point where the best insurance policy is simply knowing how the system works, and then carrying a few tools and supplies that can keep you going - - regardless of which component lets go.

After studying the options, my own favorite approach is to first, learn how your particular version works - - and then, add something like our Genie Lamp add-on which (for less than 20 bucks) allows you to monitor the status of the AutoPark system from the dashboard. At a glance, you can see if everything is OK, if trouble is just starting to brew, or if a lockup is in process.

I'm sure there are a lot of other good ideas out there - - It's always good to look at all the options.

oldusedbear

[TandW]

OUB, as you know, my existing alarm system is disfunctional and I am satisfied with my "workaround". My next project involves isolating the "Autopark" system from the ignition. A "UPS" if you will. Thanks for your knowledgeable input, as you are an invaluable resource to this forum!! Good luck!!