Omnistep internal switch

[Randonneur]

We have an Omnistep which retracts when engine is started. The button just inside the door which is supposed to operate the step is doing nothing. Anyone any ideas. Could it be that the button is controlled by the leisure battery when the engine is not running?

[yoko8pups]

We had the same problem and tried various solutions. It depends if you can hear the electricity when you press the switch. We couldn't. It wasn't a fuse and we had the motor serviced. A Spanish motorhome and caravan repairer found that some wires right underneath the van had seized up and were cleaned, Bingo!

[Derek Uzzell]

Randonneur

 

Lots of on-line discussion on Omnistep problems

 

https://tinyurl.com/y9y7nqdk

 

I’ve attached a picture of the wiring diagram for a Thule step (the Omni-Step’s diagram will be similar). The step’s power-source is a 12V battery (normally the motorhome’s leisure-battery) and automatic retraction is via a relay triggered by a signal when the motorhome’s motor is started.

[Alanb]

Randonneur,

 

From your post and by consulting online copies of the Autotrail manual, I find that you have the more complicated single push button system. Unfortunately Autotrail / Sargents database is faulty and will not download the wiring diagrams for 2007 models. I have had to use the 2008 handbook instead.

 

The diagram is of minimal help as the wire from the push button goes into a box labelled EM50, from which the power wires to the step motor emerge.

 

However most electrical faults have simple causes so here are a few checks to carry out.

 

1. Check for a faulty fuse, but do be aware that fuses usually blow for a reason. Given the age of your MH, which is only slightly younger than mine, this could be due to a stiff step mechanism causing the motor to tke excessive current.

 

2. As has been suggested, but I think that something was lost in the translation, there is the possibility of corroded connectors close to the step. However such connectors are not shown on the in the Auto trail manual.

 

3. The controlling push button may have failed. If you can manage to remove or otherwise access the push button terminals, test for voltage across the button with a multimeter, both with the button released. If this voltage does not go away when the button is pressed, that would suggest a faulty button. For information the white/orange wire at the push button is habitation negative, and the blue/red wire is the control input to the EM50 module.

 

In addition you should note that the wire colours on the Autotrail diagram do not match those on other installations. The motor wires are shown as red/blue, and red/white on the Autotrail diagram instead of the more usual orange and violet. The "step IN" limit switch wires are shown as white/orange (-ve), and blue/white leading to the EM50. Typical colours for these latter two wires are brown and grey respectively.

 

Alan

[Keithl]

Alanb - 2018-05-29 10:06 AM

...Unfortunately Autotrail / Sargents database is faulty and will not download the wiring diagrams for 2007 models. I have had to use the 2008 handbook instead.

 

Alan

 

Alan,

 

I managed to download the 2007 Schematics from here...

 

https://sargentltd.co.uk/tech-support/article/26/download/300

 

But still not sure if it will help Randonneur as all the step wires run back to the EM50!

 

Keith.

 

PS page 5 shows the step wiring.

[Randonneur]

An update. At the interior switch panel there is also a switch for the interior doorstep light. Have had a multimeter on it this morning and am getting 12v at the light switch but nothing at the step button, so it looks like there is a problem with the wire from this button to the box on the step, problem is I can't get the step out to take the cover off the step motor. Obviously there must be some way of getting the step out.

[Keithl]

Randonneur - 2018-05-29 12:21 PM

 

An update. At the interior switch panel there is also a switch for the interior doorstep light. Have had a multimeter on it this morning and am getting 12v at the light switch but nothing at the step button, so it looks like there is a problem with the wire from this button to the box on the step, problem is I can't get the step out to take the cover off the step motor. Obviously there must be some way of getting the step out.

 

Looking at the wiring diagram there will not be 12 V at either side of the switch. One side is connected to Ground (White/Orange wire) and the other side is the 'signal' to the EM50 (Blue/Red wire).

 

All you will be able to do is check that the ground side is actually connected to ground and that the switch operates correctly (it looks as though it may possibly be a Normally Closed switch, ie push to break connection). And maybe find the Blue/Red wire at the EM50 and check operation there.

 

Keith.

[Alanb]

Keith,

 

Thanks for the link. I have downloaded the diagrams, but cannot see any difference in this area to the 2008 version. I regret that I cannot see the basis for your deduction tha the switch is NC. The diagram is rather vague.

 

Randonneur,

 

Whatever the switch configuration, you should see a change of voltage across it, when the button is pressed. If no voltage in either state, continue as suggested above by Keith.

 

Alan

[MartinP]

I had initially intermittent then progressively worsening problems with my step a couple of years ago (Autotrail Arapaho 2008). Tried tracing throuh, elimination etc. Fed up with crawling under van, cleaning contacts, taking on & off etc. Couln't find a fault. When we were reduced to using a plastic step I booked it into Todds Motorhomes nr Preston.

Within an hour they had traced the fault to a failed EM50 module, replaced it with a refurbed unit, sorted my problem and charged me approx £70.

I was delighted. B-)

[Alanb]

MartinP - 2018-05-30 4:51 PM

 

I had initially intermittent then progressively worsening problems with my step a couple of years ago (Autotrail Arapaho 2008). Tried tracing throuh, elimination etc. Fed up with crawling under van, cleaning contacts, taking on & off etc. Couln't find a fault. When we were reduced to using a plastic step I booked it into Todds Motorhomes nr Preston.

Within an hour they had traced the fault to a failed EM50 module, replaced it with a refurbed unit, sorted my problem and charged me approx £70.

I was delighted. B-)

 

An interesting contribution. The EM50 module will need to detect when the step is fully extended, probably by reacting to the motor stalling current. It will also need to remember the step position, so as to select the correct direction at the next push of the button.

 

At £70 for a technician for about an hour plus a replacement unit, yes you had good reason to be pleased.

Unfortunately this is the disadvantage of the single button contol system, as against the combined extend and retract (lower and raise) switch. Presunably with the single button system has the slight advantage of only needing a short press on the button, with automatic cutout at the end of travel.

 

I am inclined to think that the single button system is more of a marketing ploy than a necessity.

 

Alan

 

 

 

 

 

 

[Randonneur]

Alanb - 2018-05-30 7:55 PM

 

MartinP - 2018-05-30 4:51 PM

 

I had initially intermittent then progressively worsening problems with my step a couple of years ago (Autotrail Arapaho 2008). Tried tracing throuh, elimination etc. Fed up with crawling under van, cleaning contacts, taking on & off etc. Couln't find a fault. When we were reduced to using a plastic step I booked it into Todds Motorhomes nr Preston.

Within an hour they had traced the fault to a failed EM50 module, replaced it with a refurbed unit, sorted my problem and charged me approx £70.

I was delighted. B-)

 

An interesting contribution. The EM50 module will need to detect when the step is fully extended, probably by reacting to the motor stalling current. It will also need to remember the step position, so as to select the correct direction at the next push of the button.

 

At £70 for a technician for about an hour plus a replacement unit, yes you had good reason to be pleased.

Unfortunately this is the disadvantage of the single button contol system, as against the combined extend and retract (lower and raise) switch. Presunably with the single button system has the slight advantage of only needing a short press on the button, with automatic cutout at the end of travel.

 

I am inclined to think that the single button system is more of a marketing ploy than a necessity.

 

Alan

 

 

You did very well there Alan, just looked at Sargent website and the EM50 are just over £123.

[MartinP]

I think NEW EM50 =£123

But REFURB was ~ £70 fitted.

I recall they said. They are a standard repair cost sent away and refitted......but we keep one in stock to save the long wait. Hence - "great service".

 

Martin

[Randonneur]

MartinP - 2018-05-31 12:13 PM

 

I think NEW EM50 =£123

But REFURB was ~ £70 fitted.

I recall they said. They are a standard repair cost sent away and refitted......but we keep one in stock to save the long wait. Hence - "great service".

 

Martin

 

Spoke to Sargent this morning and they seem to think (without looking at it) that its ok. They said that it takes 5amps for the step to work and if it is more than that then it will be stuck, which is not unusual. Until we can get it out we can't look at the motor.