Thule Omnistep electrics

[Harrythevan]

The step on my 2012 Swift Sundance never worked when I bought it (second-hand, and the non-functional step was flagged so not an issue there). I removed the motor & gearbox and got everything moving nicely. Checked the motor and it whizzes away happily when 12V is applied to it. Put it all back together and still nothing happens when I press the switch. Checked all the connections and they seem good, but when I press the switch to operate the step, I get 12V across the wires as expected, but only for a fraction of a second, then this drops to zero almost immediately, when holding the switch in.
Any electrical gurus point me where to look next?
(I've looked through the forums and can't find anything similar)

 

[Cush]

Dodgy switch?

 

[StillGoing]

Does this help?

 

[yorkiebar]

Check that the microswitch that is activated when the step is retracted isn't jammed up. This happened to someone on here recently, sand was gumming up the switch stopping the step retracting.

 

[Harrythevan]

It's not the switch at the step, as I'm getting these voltages from the connector before the step, with the step motor and micro switch isolated. I'm thinking relay but can't find one.

 

[StillGoing]

I have a different motorhome but some of my step electrics are under the driver’s seat.

 

[Basa]

My Thule step stopped working and I thought it was electrical but in fact it was the little cog that drives the step in and out
The cog is made of a very poor alloy material
Replaced it with a new one from Thule made from a much better material
You can get a maintenance kit and it’s not that expensive

 

[Diabalo]

The relay may be in the pillar behind the driver's seat, you need to remove the plastic trim. Or it could be at the side of the drivers seat where the handbrake is, again you need to remove the plastic trim.

 

[Cush]

My relay was behind the fridge, on the bulkhead next to the door. Will be model specific, but made sense as the fride relay activates on engine start up too.

 

[Harrythevan]

My question is would a faulty relay cause the immediate voltage drop to zero? If not the relay, what?

 

[Two on Tour]

My question is would a faulty relay cause the immediate voltage drop to zero? If not the relay, what?

A bad earth or corroded connection.

 

[yorkiebar]

It's not the switch at the step, as I'm getting these voltages from the connector before the step, with the step motor and micro switch isolated. I'm thinking relay but can't find one.

Just to double check, when I mentioned the micro switch I meant the switch built into the step mechanism to detect when the step has retracted ( S2 in the Thule diagram ), not the switch used to operate the switch by the user ( S1 in the diagram).
Hopefully you also meant you'd isolated the S2 microswitch but thought worth a double check.

Assuming you've ruled out a fault with S2 ( I would check its operation with a multimeter ) then try and find the relay if there is one, they're only fitted when the step has auto-retract when the ignition is activated.

 

[Harrythevan]

Just to double check, when I mentioned the micro switch I meant the switch built into the step mechanism to detect when the step has retracted ( S2 in the Thule diagram ), not the switch used to operate the switch by the user ( S1 in the diagram).
Hopefully you also meant you'd isolated the S2 microswitch but thought worth a double check.

Assuming you've ruled out a fault with S2 ( I would check its operation with a multimeter ) then try and find the relay if there is one, they're only fitted when the step has auto-retract when the ignition is activated.

Yes, I disconnected the entire step assembly (4-way connector lurking inaccessibly iunder the van:-( ) so neither the motor or the S2 switch were connected, and checked the voltage across the orange and purple wires as per Swift's instructions. Get battery voltage for a fraction of a second only then drops to zero. I have found the relay (I can hear it clicking at least) but it appears to be built into the Sargent EC450 control unit. Can't even see how to get the control iunit out to have a look. I am looking into simply running power to the step through the rocker switch and just using it manually as it were, ignoring the automatic retraction stuff completely. Does that make sense? And would it be sensible to run it rhough a relay to prevent frying the rocker swith, which doesn't look massively robust?

 

[yorkiebar]

Yes, I disconnected the entire step assembly (4-way connector lurking inaccessibly iunder the van:-( ) so neither the motor or the S2 switch were connected, and checked the voltage across the orange and purple wires as per Swift's instructions. Get battery voltage for a fraction of a second only then drops to zero. I have found the relay (I can hear it clicking at least) but it appears to be built into the Sargent EC450 control unit. Can't even see how to get the control iunit out to have a look. I am looking into simply running power to the step through the rocker switch and just using it manually as it were, ignoring the automatic retraction stuff completely. Does that make sense? And would it be sensible to run it rhough a relay to prevent frying the rocker swith, which doesn't look massively robust?

What actions do you take to cause the relay to switch on/off ?

 

[Harrythevan]

I press the rocker switch and hold it down. Whichever way I press, up or down, the relay clicks on then after maybe a second clicks off.

 

[yorkiebar]

Strange one. If the step were wired as per the Thule diagram then there shouldn't be any activating of a relay when pressing the in/out switch. The auto-retract relay is only energised when the ignition is switched on and while the step is being retracted automatically. When it has retracted, the S2 microswitch is activated and this ( normally closed ) switch opens and shuts off the -ve connection to the relay coil. I think the capacitor wired in parallel with the relay coil is to keep the relay activated for a short additional time to ensure the step is fully retracted. Perhaps someone has screwed up the relay wiring in your case ?

 

[Harrythevan]

Don't know. I don't know if the step ever worked before, tbh. It certainly is supposed (according too the manual) to autoretract, but since I can't get the step out without removing the motor this has never arisen! I've asked Swift but they can by slow to respond, going to try jury-rigging something.

 

[donkey]

On my Swift which also had Sargent control gear, There was a setting in the advanced setting menu. It enabled the user to change the time duration for step actuation. If you look up Sargent advanced menu options, it will tell you how to access.

Geoff

 

[Harrythevan]

Having a look at the rocker switch now. Only got three wires to it - two red/white one orange/white. Nether of the earth (centre) tabs have any connection. The orange/white (call it pin 2) gives no resistance to earth. The two red/white wires (pins 1 & 3) give me 5V, dropping instantly to zero when I operate the switch. Centre tab (pin 4) gives me zero resistance to earth when I operate the switch.
Baffled I is.

 

[Harrythevan]

On my Swift which also had Sargent control gear, There was a setting in the advanced setting menu. It enabled the user to change the time duration for step actuation. If you look up Sargent advanced menu options, it will tell you how to access.

Geoff

Thanks, Geoff, already been in amongst all that. Duration was set to the recommended 27. Nothing makes any difference, all I have done for now is turn off the step auto functions to shut off the buzzer that sounds if the step isn't fully retracted.

 

[2bob]

on you step button like a car door one if so look at the pop rivet

 

[Harrythevan]

Thought I'd update in case anyone has similar problems. I've heard back from Swift technical support (who I've always found very good if a bit slow to reply). After I described all the symptoms, they tell me the problem lies in the Sargent control unit (EC450 in my case) - a "polyfuse" (whatever one of those might be) has failed. Now waiting to hear from Sargent how we get that sorted. I doubt it's plugging in a new fuse :-(

 

[Mikemfg]

Google.... Polyfuse..
To find such a thing, it does exist..

 

[Mikemfg]

polyfuse in a sargent in a ec450












If you are looking for the polyfuse in a Sargent EC450 power system, it is soldered directly onto the internal printed circuit board (PCB) inside either the main Power Supply Unit (PSU) or its associated vehicle interface unit (like the EM40/EM50). It is not a standard, user-replaceable blade fuse that you can pull out from the front panel. [1, 2, 3, 4, 5]

 

[GeoffnDee]

Thought I'd update in case anyone has similar problems. I've heard back from Swift technical support (who I've always found very good if a bit slow to reply). After I described all the symptoms, they tell me the problem lies in the Sargent control unit (EC450 in my case) - a "polyfuse" (whatever one of those might be) has failed. Now waiting to hear from Sargent how we get that sorted. I doubt it's plugging in a new fuse :-(

If Sargent cannot help try www.apuljackelectronics.co.uk they also repair these units.