Steps: 20 AMP Fuse Location

[don_kleinschnitz]

My steps finally, after many months of intermittent operation, QUIT!

There is no 12V to the 4 pin connector going to the controller.

Can anyone tell me where the 20 amp auto-reset breaker is ???

See the circle in the attached diagram for the fuse I am looking for.

[JFlightRisk]

I might think it's near the coach battery. The red wire that it's inline to, goes to a solenoid that's powered from it. Maybe on the firewall, or near the passenger side fender. Only a guess from looking at the schematic.

[dxrobertson]

On my Entegra the step breaker is near the aux start solenoid under the hood.

There is also an inline fuse in the mess of wires under the step going to the control board.

[don_kleinschnitz]

Update:
I found out why my steps did not have 12V on the 4 pin connector down at the step.

The chassis battery was dead ...... doh!

My guess is that the step jammed and stayed on and killed the battery... I think.

Before this happened the step was operating erratically and getting stuck in the 1/2 in & out position. It's done this multiple times but then fixed itself. Lubing the actuator, etc. did not help.

I recharged the battery and now the step is working and it did not draw down the battery overnight.

Learnings:

1. The step is run off the chassis battery not the house battery. This means, as I have just experienced, a step stuck-on failure can drain the chassis battery and you will not be able to start the RV (other than using the AUX). I wonder if a step main power switch would be useful that disconnects the chassis battery from the step.
   
2. The 20A fuse for the step is under the hood next to the battery disconnect switch. It's an auto-reset switch but I do not know what that technically means. I need to find a part # and spec sheet on that part.
   
3. I put a clamp amp meter on the step supply lead just after the 20A fuse. The step draws about 2-3 amps as it extends/retracts and then it hits the stops and draws about 16A which causes it to shut off. I am assuming the controller is watching the current and shuts the motor off when it sees a "stall" current. This technique eliminates the need for end-stop sensors. That said it is an "open-loop" system meaning that if it does not see a high current transition it may keep the motor on? The best I could tell [with a clamp meter] when the controller shuts off it does not draw any quiescent current.
   
4. I am somewhat worried that something other than the step is really what may have killed the battery. Given its open-loop operation, I would have thought that the controller would also shut the step motor off if it is drawing current for an extended time.
5. The schematic shows the purple wire from the controller going to the same light the "exterior light" switch controls. I don't think my exterior lights come on when the step is actuated, need to check.

Given mine and other step failures I read about on this forum, it's clear that these steps have poor reliability, I am starting to think I would be happy with a step that was MANUAL. I guess that is what the on/off switch is intended to do? A handle that lowered and raised the step kinda thing would be better with an alarm that warns you if the step is out and the ignition is on...

This event also caused me to start the design of a handheld step-tester that would allow me to plug into the 4 pin harness and tell if the problem is the power, controller, or motor. My first sketch is attached in case anyone has an interest in building one. Caution this design is untested..... proceed at your own risk!

As I was working on this problem I am again reminded how crappy the wiring is in this RV and how inadequate the schematics are. The ground wire on the 4 pin harness is about 1 ft too long and is wrapped back on itself inside the conduit. The black conduit was not properly tie-wrapped to the frame.

The in-dash chassis & coach battery display I added to the dash was invaluable in troubleshooting this problem. It made it easy to see that the chassis battery was dead and I could watch its voltage during charging.
https://www.jaycoowners.com/forums/f...tml#post955552
Attached is a picture of the latest version of the panel. I wired the display through a switch to the house battery. That way I can see the display with the ignition off and I can read both the chassis battery & house battery. Yes, I have to make sure I turn it off.
So my first indication that the chassis battery was dead was when I turned on this panel and the chassis battery showed 2V and the house was 12V.

The drawing for this area "Schematic, Elec 12V Chassis Greyhawk (Ford Gas)" does not give adequate details of the step harness as it connects to the step controller. The diagram stops at a box called "Double Electronic Step Harness". So I created a detailed drawing that I could use for troubleshooting, it's attached.
I later found a drawing "Schematic, Elec 12V Chassis (Greyhawk Esteem)" that had more detail.

I plan to make these drawings "pretty" later and will update this post with those attachements.

Enjoy, all suggestions and improvements are appreciated
Don

[JFlightRisk]

snip...

The 20A fuse for the step is under the hood next to the battery disconnect switch. It's an auto-reset switch but I do not know what that technically means. I need to find a part # and spec sheet on that part.

Very helpful write up, thanks for your groundwork.

The red covered piece is actually just a resetting circuit breaker, and identical ones are available on Amazon in several amperages. Nice to have instead of an inline fuse.

[dxrobertson]

Originally Posted by don_kleinschnitz

Given mine and other step failures I read about on this forum, it's clear that these steps have poor reliability, I am starting to think I would be happy with a step that was MANUAL.

Thats exactly what I did.

These steps have been nothing but an irritant to me since I bought the RV. I ripped the control board out. Ran a new 12V supply to the existing Step SW, to act as a master on/off. Ran from that SW to a new rocker SW to slide steps in/out. Wired the step light back directly into the outside light supply wire.

It actually was not difficult, all the wiring was already there or nearby.

[ChristopherW]

Nice description of the problem & write-up. Thanks for posting the info & solution, it really helps the rest of us.
Just FYI, my 2013 Greyhawk steps have a fuse in a black holder under the steps among the many wires.

[don_kleinschnitz]

Back from a weekend camp and the step is again working.
No idea what goes wrong with it???

Scheduled to go to the dealer but I bet they will argue it's working or at best replace "something".

Since it is working again and the coach battery was not drawn down all weekend I am convinced the step motor stayed on and drained the coach battery.

Here are some current probe measurements while operating the step:

When the step hits the stops it draws appreciably more current.
Here are some peak current values

Extend: Stall =19 amps, Run = 3.5 amps
Retract: Stall =16 amps, Run = 7 amps

It's interesting to note that the step extends/retracts in about 2 seconds and the stall portion of this is <1 second.

You will see similiar measurements in this video: https://youtu.be/62z5-8TwnJU

I am still concerned that the step can jam and kill the coach battery as it did a week ago!

Looking at the design it looks like the step draws about 4-7 amps when the motor is energized to extend or retract the step. The motor is operating for 1-2 seconds and the motor is in a stall for less than 1 second.

This circuit is protected by a 20 amp resettable fuse, like this one: https://amzn.to/3yXMBwP

Thinking out loud:

• The current in my steps circuit never reaches 20 amps even when the motor stalls. I wonder if that fuse is actually protecting anything? The only way that breaker would trip is if there was a 20 amp draw for an extended time.
  
• Evidentially the controller does not shut off the motor if the normal current to the motor stays below the stall current for an extended time? That is, the step is jammed but the stall current is <20 amps.
  
• Evidentially the step can jam and the motor current will not blow the 20 Amp breaker. No idea what the current was while killing my battery. I am assuming it was 16-19 amps.

Ideas to prevent a jammed step from killing the battery?

• Somehow monitor the step current and set off an alarm if the step is energized too long?
  
• Replace the resettable fuse with a lower amperage one (5 amps). Since it takes some time for a resettable fuse to heat up and open, normal operation, which is 2 seconds, would not throw the breaker. Longer operation at >= 5 amps would throw the breaker. Could not find a resettable fuse < 5A. This setup may also not throw the breaker.
  
• Add a slo blow glass fuse to the circuit that is sized at the run current assuming it will take > 2 seconds to blow.

... thinking!

[don_kleinschnitz]

Does anyone know what the manufacturer and part # for the step motor 2 pin connector is?

I am starting my tester build and would like to make my own cables.