Hi, I am a new member here and was after some advice if possible. Just back Caravanning after a 20 year break. I have purchased a lunar Clubman 2015. I have towed it about 6 times now with 2 different tow cars. The caravan seems to have a fault with the ATC. The ATC seems to be fine when plugging in i.e I can hear it initiate as soon as it is plugged in regardless of status of car ignition. I have the green light. I have wiggled the cables and it does not seem to start stop in terms of power-up. But it seems to randomly have episodes of breaking (on and off several times) fairly frequently when being towed. These don’t seem associated with speed or the caravan stability. For example I tried the other day to pull on the carriageway up the slip road but could not get up above 40 mph to join the traffic due to the ATC breaking on and off. This seems random and intermittent. Some trips it happens frequently other trips it’s does not occur. I don’t think it a car electrics issue as it happens with both cars (but maybe if it’s on both cars) but unlikely??? I have ready through the posts here regarding ATC and they do point more towards the cars and supply issues??? Anyone have similar issues or ideas before I investigate further? I purchased privately so it not just a case of dropping it back to the dealer under warrantee. Thanks JB
ATC random breaking
- Thread starter Jimmyboy
- Start date
The "pulling off " case might be associated with that move instigating a reasonable swing, this can happen if the main route has heavy tracking groove lines [those caused by HGVs]. Again, when running straight if the van tracks and "jumps" into or out of these grooves that can induce our ATC to give a checking tug. It tends to be the case the van wants to run in these tills it has little option but "snatch" itself out of them, or drop into them, with resulting an otherwise un-concerning minor sway.
But in all cases that is all it ever is, just a single short-lived check, never for us has it been what I would call "sustained".
But in all cases that is all it ever is, just a single short-lived check, never for us has it been what I would call "sustained".
The first thing to check is is if your outfit is properly loaded and the ATC isnt actually responding to conditions which are causing it to act,
ATC should never be relied on to make an unsuitable outfit able to be towed. It should only be considered to be like seat belts... there just in case not to hold in place under normal conditions.
You outfit should be stable under normal towing.
Apart from rechecking all the electrical connections, it seems you should perhaps arrange to have the system checked by an AlKo dealer.
ATC should never be relied on to make an unsuitable outfit able to be towed. It should only be considered to be like seat belts... there just in case not to hold in place under normal conditions.
You outfit should be stable under normal towing.
Apart from rechecking all the electrical connections, it seems you should perhaps arrange to have the system checked by an AlKo dealer.
Have you confirmed its actually the ATC that is braking you?
Could be that your break shoes have come apart, and the friction material is randomly binding inside the drum
Could be that your break shoes have come apart, and the friction material is randomly binding inside the drum
The ATC will give a slight tug every-so-often. Which I find reassuring, indicating that it is operating. However, if you think it is more sustained. Then it is likely that the power supply is being briefly interupted. This will cause the ATC to run through its start up checks which involves applying the brakes.
The intermittent interruption could be anywhere in the power supply line.
I believe the unit has a memory which can be read with the right equipment. This may help.
John
The intermittent interruption could be anywhere in the power supply line.
I believe the unit has a memory which can be read with the right equipment. This may help.
John
Ironically, I got to the bottom of another thread, and found this "Alko ATC jammed / stuck on ... evidently not a 'fail safe' system" at the top of the similar thread suggestions!
The situation reads very similarly, and a new thought has occured to me:-
We have seen an increase in the number of tow vehicles with caravan battery and fridge problems which could be the result of smart alternators which are now being fitted to new vehicles. These have the ability to stop producing 12V power when the cars systems don't need it. This is to improve vehicle efficiency. During these "Off" periods, no power is sent to the caravans auxiliary circuits, thus the caravans battery and fridge don't receive any power.
If the trailers ATC is also wired to the caravans auxiliary systems supply, it would also see these same power outages cussing it to to a start up cycle each time the power is restored.
Unless the towbar fitters are specifically told the auxiliary sockets must have Permanent or constant 12V power, they may not ensure that is the case.
The situation reads very similarly, and a new thought has occured to me:-
We have seen an increase in the number of tow vehicles with caravan battery and fridge problems which could be the result of smart alternators which are now being fitted to new vehicles. These have the ability to stop producing 12V power when the cars systems don't need it. This is to improve vehicle efficiency. During these "Off" periods, no power is sent to the caravans auxiliary circuits, thus the caravans battery and fridge don't receive any power.
If the trailers ATC is also wired to the caravans auxiliary systems supply, it would also see these same power outages cussing it to to a start up cycle each time the power is restored.
Unless the towbar fitters are specifically told the auxiliary sockets must have Permanent or constant 12V power, they may not ensure that is the case.
As long as I have had ATC it is mandatory it is fed a 20 amp fused permanently live power feed direct from the towing vehicles battery. Will a smart alternator affect this scenario? It is possible the caravans hitch cable wiring has developed a fault. Cheap to investigate and remedy.
It seems there may still be a lack of expertise among "specialist" towbar fitters when it comes to wiring cars with smart alternators - bear in mind that they've been around for 25 years and almost all new cars have had them fitted for many years.
As a layman how would one confirm that the vehicle with the Smart alternator has been wired correctly for the ATC to work?
That may be so, but if the car has been changed, and the instruction to install the ATC supply has not been passed on to the towbar fitters in an unambiguous way, it's is of course possible it may not have been installed to the ATC requirements.
I don't think a layman could - it would need an understanding of 12v wiring to discuss the detail with the fitter and/or the ability to trace the additional wiring and understand its logic.
The whole point about paying a specialist is that they're expected to have the knowledge and experience that a layman doesn't have.
True, but they are not mind readers, and if a caravanner gets a new car, and presents it to a towbar fitter for towbar and wiring to be fitted, unless you specifically ask for a continuous 12V feed, you may not get it.
It's up to the caravanner to make the need clear.
When I had the towbar fitted last year I was asked whether I wanted the 12v fridge connection which was an extra. As I did not see any point of having the 12v for the fridge, I turned it down.
This thread has made me aware that we may not have a continuous 12v supply to the ATC, but I have no way of checking. I have not noticed any issues while towing over the past several months as caravan is correctly loaded etc.
In the UK, specifying that the after-market fitting is to tow a caravan should be sufficient - not necessarily true abroad nor for a factory-fit towbar where the fridge requirement needs to be made clear.
Sadly not true, there are many cases where a towbar may be requested, but not necessarily for towing a caravan, so the additional auxillary 12V connections needed for caravans are omitted in standard tow bar fittings.
You should specifically state it's for a caravan which needs continuous 12V circuits.
First not an area of my expertise, but I thought that maintained feeds for all battery users are "maintained" whether a smart alternator is fitted or not, what modulates is the charging voltage, so the battery post voltages.
The issue we with caravans have I thought was down to this modulation changing that voltage at the feeds at the car's socket?
This from circa 15 volts to sub 13 or such lower figure that does not load the alternator with unrequired charging. It is the battery, as opposed to the alternator voltage that matters to feeds taken from the battery.
The implications to us is that that lower battery voltage, can't shift sufficient "power" to remote users like the caravan's fridge, because of the voltage drop the "current" flowing creates in the overall run from the battery.
However, we know the ATC functions even with a stopped engine, so at battery post levels at battery resting volts. It does this even with the current draw and so the voltage losses the ATC's power needs require. Well mine does.
Does this not imply that whether a smart technology alternator is generating or not the ATC can work from the vehicle's battery? If so the battery is up to the job, the connections are probably "right" and the efforts or not of the alternator are not relevant.
The fridge not being effective being quite understandable, but IMO not the ATC failing to cycle fully.
That the ATC functions when hooking up indicates it has a feed, a question I have is does it happen with the vehicle engine stopped?
Last edited:
I know that when I hook up my van to the car, 2014 Santa Fe, with the engine not running, the ATC cycles through the set up.
One thing I did find when the car was new, was the earth returns were all linked together in the car socket, I separated these out and earthed the fridge and Atc return separately.
One thing I did find when the car was new, was the earth returns were all linked together in the car socket, I separated these out and earthed the fridge and Atc return separately.
I would think that yours is OK. If the ATC was interrupted it would recycle and fully apply the brakes. You would really feel this.
Also, there is an indication is when you plug your van in. With the engine off. You should hear the ATC run through its checks.
John
The last few comments are fine but do not address the point I'm making. If you do not state or have clarified at the time of fitting the towing kit that you intend to tow a caravan and it has ATC, the fitting company may not wire the appropriate features, such that with a smart alternator, it's possible the wrong (non continuous feed) might be used which could give rise to the symptoms experienced.
If the ATC functions as it should with the engine not running, as said this points to a high probability the pins for that are correctly wired up; agree not totally.
If the ATC induced braking drag is sustained, it really is strongly pointing to a connection not being sound; ie the ATC lost power whilst applying the brakes, and for as long as that braking effect lasts. In action with minor harmless though responded to swings it is but a very short period braking experience.
If the ATC induced braking drag is sustained, it really is strongly pointing to a connection not being sound; ie the ATC lost power whilst applying the brakes, and for as long as that braking effect lasts. In action with minor harmless though responded to swings it is but a very short period braking experience.
I do not think anyone contested your point. Just expressed their disappointment that fitters are so poorly trained they are not aware and are not advising their customers properly.
Some fitters combine the live feed to the battery, fridge and ATC with voltage-sensing relays and undersized cabling.
It is necessary for the customer to specify. But very sad that that is the case.
John
That’s possible but probably a rarity today. Tow bar fitters have been wiring ATC electrics since before the 13 pin was invented. Donkey years. Hitching up should always be done with ignition and engine off. ATC will cycle as soon as attached to the car. But mistakes do happen😜
Last edited:
But if the ATC requires a specialist circuit over and above the standard kit for the vehicle. it will not be fitted. So its essential that if you want to have ATC compatibility you have to make sure its part if the contract to fit the wiring. You cant assume a car with a hitch and wiring will be automatically compatible. It not a fore gone requirement for most trailers.
....ATC is always wired by convention to the permanent 12 volt supply which is always present in a 12S socket and the more modern 13 pin socket.
This is why the ATC performs its set up test on connection.
The OP has narrowed the problem to the caravan as the problem has occurred with 2 different tow cars.
IMO .....I agree with others.
There is an intermittent wiring disconnection in the 12volt supply to the ATC.
I would look for a fitted connector under the front of the caravan and check it for electrical continuity.
These connectors are exposed to the elements.
This is why the ATC performs its set up test on connection.
The OP has narrowed the problem to the caravan as the problem has occurred with 2 different tow cars.
IMO .....I agree with others.
There is an intermittent wiring disconnection in the 12volt supply to the ATC.
I would look for a fitted connector under the front of the caravan and check it for electrical continuity.
These connectors are exposed to the elements.
We had the Jeep done last year by a Nationwide specialist company, but stating we did not require the permanent feed for the fridge has raised concerns. We seldom connect up with the engine switched off .
I would normally reverse up with OH guiding me, then lower hitch onto towball. connect breakaway and lastly the electrics. ATC does its thing and green light is on.
Facebook
Twitter