mgbken Posted March 18, 2020 Share Posted March 18, 2020 2003 Bessacar E425 - Omnistep has suddenly stopped retracting when engine starts. Not sure exactly when but only recent electrical work was to replace the leisure battery. Have read various threads and found Clive Motts very useful explanation and diagram. However still struggling. To the right side under the Ducato bonnet is the fuse and relay box. Fuses all appear OK. Under a cover at top middle of engine bay (remove two nuts to remove cover) there are further relays and fuses - 3 fuses 15amp + 2 x 20 amp and 2 relays. This, was where one thread said the fridge relay was situated on a similar Bessacar. Found one blown 20 amp fuse changed it and all others - not solved problem. When looking at the two adjacent relays trying to follow Clive's notes he refers to terminal 87a - neither relay has one just an 86 and 87. So have I not yet found the fridge relay? is it perhaps somewhere else? If so any idea where as despite looking in obvious places can't see another relay that looks right. I proposed to replace both relays on a trial and error basis but the writing on the relays has almost worn off so I can't tell what size/type they are. Halfords seem to sell a few that look similar but there are differences between the ones on sale, What should I be buying? Have also removed step motor cover, the wiring colours inside are not the same as the ones leaving the control switch. There is purple and a grey wire and an external rubber covered button on the motor cover. Not sure what this does but inside the cover the connecting wire to this rubber button/switch is heat shrunk so I am reluctant to disturb it. Seems quite clean inside the cover. Is this a red herring? Any help appreciated, Link to comment Share on other sites More sharing options...
lancepar Posted March 18, 2020 Share Posted March 18, 2020 When my MH step stops working a spray with contact/maintenance spray all over the cutout switch gets it working again. B-) (photo attached) Link to comment Share on other sites More sharing options...
witzend Posted March 18, 2020 Share Posted March 18, 2020 87 & 87a are 2 outlets to allow 2 connection to the same side of the switch some have both some don't. When my step had the same fault it was a break in the D+ wire which is the thin wire coming from the alternator but ign light was dimly lite and no charge going to leisure battery's Link to comment Share on other sites More sharing options...
mgbken Posted March 18, 2020 Author Share Posted March 18, 2020 Thanks - looks different to mine. I think the switch on mine is the rubber covered button on outside of step motor cover which seems to be in contact with the step when it retracts. I have squirted it liberally with WD40 but does not seem to be solution. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted March 18, 2020 Share Posted March 18, 2020 I notice that you’ve asked about a relay on another (2016) forum thread https://forums.outandaboutlive.co.uk/forums/Motorhomes/Motorhome-Matters/omnistep-switch/45633/#M640366 I have attached a diagram for a Thule step’s wiring (the wiring of an earlier Omnistep should be similar) and - when the step has automatic retraction when the motorhome’s engine is started - the additional ‘step-relay' appears to be an ordinary 12V 5-pole changeover type. Such relays are readily available and there’s a Bosch-branded example in this ebay advert https://tinyurl.com/tyc2yls A wiring diagram for a 2003 model-year Bessacarr E400 Series motorhome is on Page 12 of this document https://orbit.brightbox.com/v1/acc-jqzwj/Swift/handbooks/pdfs/000/000/181/original/1048658_Bess_MH_Service_Book_2003.pdf?1472743583 but I can’t advise on where Swift would have put the step-relay. (I’m guessing that it would not be in your motorhome’s engine compartment.) Link to comment Share on other sites More sharing options...
plwsm2000 Posted March 18, 2020 Share Posted March 18, 2020 Unfortunately, there are several ways that the Omnistep/Project2000 can be wired and you need to know how your van is wired in order to diagnose the problem. The main difference is how the motor and/or auto-retract relay is powered. I have come across the following methods (they all work, but some have advantages and/or disadvantages over the other methods so there is no right or wrong way IMO) 1) Motor and relay powered from starter battery (as in page 12 of the manual that Derek linked to). The step switch is fed from the starter battery (even when the ignition is off) so you can operate the step without the engine on. When the engine is running, the relay that powers the fridge heater also provides power to the step auto-retract relay. If the step is out, the limit switch inside the step mechanism will be closed and so the relay gets energized and powers the motor to retract. The limit switch opens when the step is fully closed. Many steps use exactly the same limit switch as used in domestic fridges to sense when the fridge door is open and turn on the light. Search on ebay for "fridge door switch" and you will find many for around £2 (same photo as Lance had posted). Note some of these have 3 terminals and are just a changeover switch - just use the 2 outside terminals. Obviously a switch designed work in your kitchen is not going to last as long underneath your vehicle so it is no surprise they often fail. They usually get stuck in the closed position even when the step is out - hence the reason why the step doesn't retract when you start the engine. 2) Motor powered from habitation battery but relay contacts and control powered from starter battery (as per Clive Motts diagram). This is virtually the same as above but the step switch is fed from the hab. battery. (Hab battery when using manual in/out switch - Starter battery for auto-retracting) 3) Motor and relay contacts powered from hab. battery but relay control (the coil) is driven from boosted D+ (very similar to fridge control relay, but uses a physically different relay). (Hab battery to power the motor in both cases - Starter battery to drive relay coil) 4) A Thule control box is used to control the step. These come in two flavours - a) One that uses relays to boost the step switch (the motor stall current can be quite high and can damage the in/out switch) b) One that monitors the motor current electronically and switches off the current when the step hits the end stop 5) Steps can be wired with no auto-retract function. (easy). 6) There are also variants of these variants!. Some of these methods use relays fitted with internal diodes and some also have a large capacitor across the relay coils (or both). The diode across the relay coil protects the limit switch from high voltage transients when the switch opens. Some use a normal relay and fit a diode externally. If you have to replace one of these, make sure the diode (or coil) is wired the correct way around. The bar (cathode) must go to the positive 12V side. The capacitor is supposed to keep the relay closed for a fraction of a second longer but unfortunately can damage the limit switch due to a high inrush current when the switch closes. 7) Different version of above that use the "ignition" or "Acc" instead of the D+ or fridge feed. The step retracts just by switching on the ignition key (rather than starting the engine). 8) Probably a few other variants that I have not seen yet! Some have buzzers and others have a warning LED to show when the step is out. Does your buzzer/LED indicate the step is out with the engine running? If not, then it is most likely your limit switch is faulty. If the buzzer/LED is on (and the step doesn't retract) it is probably the relay (or a fuse depending on how it is wired). The relay is a simple automotive relay that has a 12V DC coil, 40 Amp rating and has a changeover function (87 is the normally open contact and 87a is normally closed. 85 is the common) Sorry for the long post. I have had to look into this on my van that has already had 2 limit switches fail and I am on my second in/out switch in about 3 years. Link to comment Share on other sites More sharing options...
Alanb Posted March 18, 2020 Share Posted March 18, 2020 plwsm2000 - 2020-03-18 4:40 PM ----------------------------------------------------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------- ----------------------------------------------------------------------------------------------------------------------------------------------- The relay is a simple automotive relay that has a 12V DC coil, 40 Amp rating and has a changeover function (87 is the normally open contact and 87a is normally closed. 85 is the common) ----------------------------------------------------------------------------------------------------------------------------------------------- The remainder was an excellent summary, but I offer the following correction, and addition. 85 is the relay coil negative, 30 is the common contact, and 86 is the coil positive. (The coil polarity is only important when using relays with an internal suppression diode in parallel with the coil.) Alan Link to comment Share on other sites More sharing options...
mgbken Posted March 18, 2020 Author Share Posted March 18, 2020 Thanks plwsm2000 I have now found a 5 pin relay inside the wardrobe by the Sargent Controller. Its near the water heater which I recently had water escaping from so that opens new possibilities, That said can't see any obvious faulty connections but there is a lot of bundles of wires in this area, I have so far replaced most fuses and the 5 pin relay and the 2 x 4 pin relays under the bonnet. Still no joy, As Clive Mott suggested I have checked that 12v hab' sockets switch off and the leisure battery is receiving charge when engine is on. Fridge is difficult to check as no fridge light or obviously accessible wiring. The buzzer did previously indicate when step is out with engine on but it's silent now. I have taken the step motor cover off, The limit switch seems part of it. It is in a rubber sleeve but looks like a car interior light door switch,,, Externally the switch appears to be clean and protected from muck and does feel like it has some spring in it so not apparently stuck, When the step retracts it touches against what I think is the limit switch. Have been reluctant to pull it apart as the back of the switch inside the cover as its heat shrunk but maybe I need to be brave. or is there another way to test if the switch is operating as it should? Any further help appreciated. Apologies that my replay is long too. Link to comment Share on other sites More sharing options...
plwsm2000 Posted March 18, 2020 Share Posted March 18, 2020 Alan, Thanks for the correction. Ken, The fact that the buzzer now doesn't work points to either a faulty limit switch or a broken wire between the switch and the relay coil (it could also be a bad earth on the other side of the switch). If you have a DMM (Digital MultiMeter) and can access the switch terminals, first check one side of the switch is earthed properly. You would need to disconnect one of the terminals to check the switch (they are usually the Faston "spade" connectors so just pull off). These switches seem to go intermittent (the step retracts occasionally, but not that often). You need to press it quite a few times and check it is ok every time. I also found that the switch "feels" ok and doesn't feel stuck. I think the problem is that the internal contacts get dirty either due to the environment or the contacts get damaged over time due to the poor design. You could check the voltage on the relay coil (but as I said above, it is unlikely to be the relay if the buzzer is not working). With the engine running terminal 85 or 86 should have 12-14V on it. One terminal (usually 85) should get grounded by the limit switch when the step is out. If you are NOT seeing this, then it is definitely the limit switch or wire to it. If you DO get one terminal grounded (and you cannot hear the relay click) then I would assume the relay is faulty. Just a word of caution though - be very careful when playing about with the step when it is powered - they can easily take a few fingers off if you get them trapped! Link to comment Share on other sites More sharing options...
Alanb Posted March 18, 2020 Share Posted March 18, 2020 Ken. I see that Phil has been posting as I was still typing. You have the luxury of two similar test procedures to choose from. You mention that the step warning buzzer is not functioning. This is important information as the buzzer will probably be connected in parallel with the relay coil. The failure of the auto retract function together with the buzzer indicates that the common supply is faulty. by supply I mean not only the +12V control supply taken from wherever, but also the connection to earth via the step limit switch. Did your step retract either when the ignition was switched ON, or when the engine was started (D+ control)? If the latter the engine will need to be started for subsequent tests, otherwise the ignition will need to be switched ON, but the engine need not be started. Test for nominal 12V at the relay coil +ve terminal (86) to earth. (You may need to rig an extended test wire to connect to a sound earth point). If 12V is present, this indicates that the ignition ON, or D+ is probably OK. Next test would be at the relay coil -ve terminal (85). If this point is at +12V, either the step limit switch, or the limit switch earth connection is suspect. I hope that the above procedure will point you in the right direction, but please keep reporting on progress. Alan Link to comment Share on other sites More sharing options...
BruceM Posted March 19, 2020 Share Posted March 19, 2020 I had a similar issue on my van which although a different make, the step appears to be a similar age (2003). In my case the step was not wired for auto retract but is wired for a warning ‘step out’ cab light which didn’t work. I eventually tracked the issue down to failure of the step limit switch (see picture). Unable to identify an identical like for like replacement I dissembled the existing switch (it clips together) and discovered that water ingress had caused the internal spring to corrode and disintegrate at one end. Rectification was just a matter of either replacing the spring if one can be located, or alternatively removing the debris, cleaning the contacts and overstretching what remained of the spring to provide sufficient pressure and travel. Once packed with grease and reassembled it’s been working perfectly for several years and will no doubt continue to do so. Link to comment Share on other sites More sharing options...
mgbken Posted March 19, 2020 Author Share Posted March 19, 2020 Thanks BruceM Your pic confirms that the limit switch is the same as mine. Removed motor cover which contains the switch and found that switch is held in by a pop rivet A similar fixing can be seen in your pic. This rivet goes through the switch body and fixes the switch to the cover. But the rivet head also makes the connection with the other terminal of the switch. The connection area of brass under the rivet head looks a bit questionable. After cleaning the brass contact area I have rigged up a test wire to a spare battery and found when switch depressed the connection is made and when released it is broken (or vice versa). So my conclusion is switch OK connection with wire which I believe is the one linking to the step buzzer may be faulty. This accords with other opinions. I will remake all connections replace pop rivet with a brass nut n bolt. Keep fingers crossed. Link to comment Share on other sites More sharing options...
mgbken Posted March 20, 2020 Author Share Posted March 20, 2020 Great news and thanks to all contributors - step now retracting, The problem was the limit switch connections and although from my initial inspection the switch looked clean and seemed not to be stuck, it looks like the manufacturers decision to make a connection using a pop rivet head that is the weak link. That said its worked for 17 years ! Worth noting that whilst wire colours on the control rocker switch matched up with Clive Motts helpful diagram at the motor end the colours were different, I guess these will vary from converter to converter and even year to year. attach a couple of pics that might help others with a similar problem Link to comment Share on other sites More sharing options...
BruceM Posted March 20, 2020 Share Posted March 20, 2020 It’s interesting what you say about the use of a rivet. Although in the photograph I posted it looks like a rivet in actual case on my step it’s a cross head counter sunk bolt with a nut on the other side. So it seems that the rivet on my step may have been previously replaced, possibly because, as you've pointed out, it’s a design weakness. Link to comment Share on other sites More sharing options...
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