colp645 Posted October 9, 2017 Share Posted October 9, 2017 Hello We have an electrical circuit fault on Swift Kontiki645 motorhome (Fiat Ducato 2.8) What should happen when you turn on the engine, if the step is out it should beep and retract Then the beep stops. It retracts but the beep continues. Also the fridge should come on at this point if the switch is turned to 12v The fuse for these is the same, it had blown, I've changed that and the relay related to it. Still same fault. I've removed the fuse for now. The step goes in and out with the manual button ok. Thanks Colin. Link to comment Share on other sites More sharing options...
paulmold Posted October 9, 2017 Share Posted October 9, 2017 Is it retracting fully? Can get gunged up with road dirt. Link to comment Share on other sites More sharing options...
colp645 Posted October 9, 2017 Author Share Posted October 9, 2017 Thanks, thats something to check, I'll take the cover off this weekend and have a look. Link to comment Share on other sites More sharing options...
Alanb Posted October 11, 2017 Share Posted October 11, 2017 Hi, As Paulmold has already suggested, the first check is to confirm that the step is retracting fully. BEFORE WORKING ON THE STEP, PLEASE REMOVE ALL APPROPRIATE FUSES. (The mechanism can operate quite sharply, and it could impart serious injury to fingers.) If the step is retracting fully, the next suspect is the step limit switch, which opens at the end of travel. In conventional installations this limit switch breaks the negative of the coil supply for a dedicated relay. The positive supply for this relay coil may be taken from either D+, or from the fridge supply, which is controlled by D+. The step retract relay is seperate from the fridge relay. However I believe that in some vehicles a more sophisticated electronic control unit is used. In the relay operated retraction system, the relay is operated when the engine is started, and its contacts supply power to retract the step, until the relay itself is switched off by the step limit switch. You state that the same (blown) fuse supplies both the fridge and the step. The step takes quite a high current when the motor is stalled at the end of steps movement (13A quoted), and the fridge will take a similar current, I would hope that the prolonged combination would blow the fuse, otherwise the step motor could be burnt out. Perhaps two years ago I had my step warning light operate intermitently while driving. This was eventually traced to a loose operating arm on the step mechanism. (The part of the scissor mechanism that operates the limit switch.) Getting access to tighten it is another story. Alan Link to comment Share on other sites More sharing options...
Basil Posted October 14, 2017 Share Posted October 14, 2017 Not familiar with Swifts step but I have experienced the flickering 'step out' light whilst the motorhome was in motion, I spent a lot of hours taking the step apart and cleaning only to find the problem still existed. It seems that, for whatever reason, some manufacturers fail to install a capacitor across the step relay coil terminals that makes the step push harder against the limit switch at the end of the steps travel by holding the relay open for a split second at the end of the steps travel. This was certainly the case in two of our motorhomes and was easily corrected by buying the appropriate capacitor from Maplins at a cost of £0.24p !!! and installing it across the appropriate terminals. You can pull the appropriate wiring diagram from the net by Googling Thule Omnistore electric step wiring, the fact it is a Thule diagram doesn't matter as the principal is the same for all makes, i.e. the step will stop as soon as the power is cut and if it has not pulled tight against the limit switch this can occur, if it isn't on yours there is no problem to correct and I believe that is what the installers rely on, perhaps getting the odd one back for rectification, but Thule Omnistor specify that it should be installed as a matter of course at the time of installation. Bas Link to comment Share on other sites More sharing options...
Alanb Posted October 14, 2017 Share Posted October 14, 2017 Thanks for the information. I was not aware of this failure on the part of some manufacturers. My IH PVC does have a 2200mfd capacitor in parallel with relay coil, which provides a small delay in the release of the relay after the limit switch has opened. However the original installation had crimped connections over a soldered joint. That was a recipe for trouble, and I rebuilt the circuit avoiding the crimp over solder connection. (For those who are puzzled, solder flows under pressure, and the crimped connection could work loose. This also applies to terminal screws in plugs etc.) Alan Link to comment Share on other sites More sharing options...
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