Power Steps Failure Symptom

During my last long trip, the power steps on my 2000 Georgie Boy motorhome failed in the closed position.  I finally got around to working on them today and here's what I learned.
1. When I opened or closed the entrance door with the ignition key in the ON position, I could hear a brief CLICK sound from the step area.  I didn't hear or see anything that indicated the motor was trying to move.
2. When I looked at the steps from beneath, all the wiring appeared intact.
3. When I tried to disconnect the pin that frees the steps from the motor assembly, I discovered a previous owner had replaced the pin with a large nail that was bent to stay in place.  I can see where it would be easy to install the nail when the steps were open, but it is very difficult to remove when the steps are stuck closed.
4. It was impossible to straighten the nail enough to remove it, so I used a cold chisel and hammer to cut the bent end off.
5. It was still difficult to remove the rest of the nail and I had to hammer it out using a long screw driver and a hammer.
6. After the nail was removed, I was able to lower the steps and examine the motor assembly more closely.
7. I repeated the test of opening and closing the door with the ignition key on, and again heard the CLICK sounds. Even with no load on the motor assembly, it showed no indication of moving.
8. In an attempt to narrow down the failed component, I disconnected the leads to the motor and hot wired them directly to a spare 12 volt battery.  The motor worked great.  By reversing the polarity I could make the motor move the arm to either the up or down position with no lag, noise or hesitation.
9. I reconnected everything, installed a proper pin and repeated the door test.  The stairs opened and closed as they should.

Now comes my question.  I didn't fix anything but I did bang around a lot and disconnect/reconnect some wires.  So maybe the problem was a loose or corroded connection that was fixed.  But maybe it wasn't.  Has anyone experienced a step motor failure that started with intermittent failures before becoming a full time problem?

Sounds like connections to me. Clean 'em up, grease 'em and reconnect. Tape 'em up tight in a way to protect from weather. check ground wire as well. Don't goop connections with a hardening sealant(silicone) unless you are prepared to cut and replace next time.

Bill

My guess... And this is based on my steps.

The motor has a "Dead spot" and due to the design of the steps the motor will nearly always stop in exactly the same (Dead) spot. so this problem should come back.  Taping on the thing with the HANDLE end of a hammer often knocked it off the dead spot.

What I did:

I opened the transmission, allowed the gears to re-position a bit, then re-closed (CAUTION SMALL PARTS LIKE TO GET LOST)

I spread a tarp below the RV first,, glad I did, it made it way easier to find the lost parts .

Now the motor stops at a completly different spot, no more tribble.

I like Driftless's suggestion as well  Go with it first, if the problem does not return,  Well, Great.  If it does, see above.

If not a corroded connection, and if not a dead spot on the motor, it may be a problem with the switch in the door where the connections between the door and the frame meet.

The door switch was not disturbed'. The wiring and the motor under the coach were disturbed, trouble shooting experience says things don't fix themselves something changed because of fiddling with things underneath. This doesn't mean that billwild is wrong, he may very well be correct, but experience says look at the last thing done when something "fixes" itself or for that matter when something goes wrong after fiddling with something related. Such as a sudden no start after new batteries installed, first thing to look at is both ends of all battery cables.

Bill

Thanks for all the replies so far.  I welcome any more folks may want to offer.

The CLICK sound each time the door was opened/closed tells me there is power going to the controller and the switch in the door is working.  That means it could be a dead spot on the motor, or a problem in the connector from the controller to the motor, or something else.  The something else I'm wondering about is this.  I would guess that the controller has some way of knowing when to shut off power to the motor when the steps are fully extended or retracted.  It could, for example, be a rapid increase in power demanded by the motor as the steps reach the end of their travel.  If there is such a system in the controller, I suppose it could cut off power to the motor until the controller is reset. .... Does anyone here know how controllers function in that regard?  What I'm trying to discover is whether the problem likely originated in the controller or in the motor.  Any educated guesses here?

Another thought: I suppose its also possible the motor assembly has an internal system to kill power when the arm reaches full travel in whichever direction power is pushing it.  Does anyone know how power to the motor is killed when the steps have reached their end position?

Amperage draw is what I understand. When the steps reach the end of in/out travel, or bind enough, the amp draw climbs and triggers shut off. Maybe the bent nail bound it up? Maybe moving the disconnected steps freed up a bind? Maybe just enough power getting through dirty connections to trigger but not enough to move things? Just pay attention to it and have some lube handy.

Bill

The control unit senses the load increase when the limit of movement is reached, not the motor.  The control unit shuts off the motor.

That nail may have been the source of a bind, but then I assume it had been working correctly for some time with that nail installed.  No?

My guess is/was a questionable connection (probably a ground).  That step motor can require a good 30amp current flow to move that step reliably.

You may want to inspect, clean and protect the connections under the step.

I would have to say it would be caused from the amperage draw from the wiring was insufficient enough to start the motor. Just taking a wild guess here. The fact that there was a nail, instead of the original pin, installed on the steps indicates there was trouble with the steps before. And the previous owner didn't think to lay something under the work area to prevent loss of small parts.

Actually, the dead spot is highest on the list. When you exercised the motor, you undoubtedly changed the stopping point and the fact that the previous owner had them disconnected suggests he likely did as well.

Ernie

Actually, the dead spot is highest on the list.

Click to expand...

It's a chicken and egg situation.  Motor dead spots can be caused by the controller NOT shutting the current off quickly when a bind/obstruction or end of travel occurs.  Many controller failures are the result of a missing critical voltage possibly (probably?) from a poor or missing connection.

Uncoupling the linkage from the step mechanism usually will not change the spot where the motor stops.  Repositioning the motor to the gearbox will. JMHO

Good info here:
http://www.rvweb.net/tech_lib/Quickee.html#dorswtst

http://rx4rv.com/archives/89

http://www.powergearus.com/parts-lookup

http://support.powergearus.com/techdocs/875.pdf

It is extremely important to keep all the rotating joints lubed on a regular basis, the system uses amp draw to regulate the stop points and any binding effects that draw.>>>Dan