Technical OMNI STEP

[jubagm]

Hi, newbie here needing help. Our omnistep on 2004 Fiat Ducato is blowing the fuses under the bonnet. I know how to change the blue one, but there is obviously a problem to keep blowing. Any help on where to begin would be gratefully received as not electrically gifted. Thankyou

 

[Communicator]

Hi,
Welcome to the forum. You have not stated when or which fuse blows, but presumably as the step is not a Fiat part, an additional fuse fitted by the converter.
To accommodate the temporary motor stalling current at the end of travel, the fuse should be rated at 20A (yellow).
However if the mechanism is stiff and in need of maintenance, the motor will be struggling and stressing the fuse during operation. In this case cleaning and lubricating the mechanism shoud help. The step action should operate with a snappy action.

However if the step is conected to auto retract when the ignition is switched on, or when the engine is started it could be that the step limit switch is failing to open. In this case the step will retract, and then stall the motor. The fuse will eventually blow to prevent further damage, including fire.

Damaged (chafed) wiring is another possibility.

I have experienced a slide out step limit switch close, with the vehicle in motion (it should stay open) when the step was visibly retracted. I eventually traced this to a loose operating arm inside the step mechanism.

For the benefit of other members, please post the eventual cure.

 

[Anthony489]

Hi

Several possibilities spring to mind.

You may have a short circuit (possibly intermittent) in the wiring somwhere e.g. due to chafing. The only remedy is careful inspection of the live cable route from fuse to step, including any switches. This will normally be wiring installed by the MH converter, not Fiat.

The motor might be being energised whilst it is encountering a high resistance to movement, e.g. it has reached the end of its travel or the mechanism needs lubrication. Under heavy load, motors draw much more current than when they are running freely. In the case of the Omnistep this could be as much as 15 Amps. Is the step fuse shared with anything else, e.g. a Fridge ? The Fuse rating in Amps must be chosen to cope with its total load.

The step is designed to retract automatically if you start the engine and it is still out. The step has an internal switch so that once it has automatically retracted, power is cut to the motor. If this switch is faulty (e.g clogged with dirt) it might allow the motor to carry on working against the end stop for a long period.

I presume you aren't holding the manual rocker switch down any longer than you need to ?

More information here: http://www.motts.org/Omnistep.htm