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I recently changed my tow car to a 2013 Volvo XC60 Auto which I am very pleased with but must admit I haven't towed with it yet.

More by chance it was already supplied with a genuine Volvo supplied detachable tow ball and Volvo marked 13 socket electrics.  This morning I thought that I would just connect the caravan to the car and check the wiring so that if there was a problem I had time to get it fixed before my first proper tow.

Everything seemed fine but the AlKo ATC would only come on when the ignition was on although the engine didn't have to be running.  I am more used to pin 9 (?) being connected directly to the battery and not via the ignition.  Is this OK or should I get it altered ?

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If the ATC is powered via a relay it will malfunction. It needs an uninterrupted supply. I write from bitter experience!

Edited by MalH
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ATC Pin 9 should be a permanent supply and not ignition controlled.

 

Check, however that, having enabled the supply via the ignition, whether it then stays 'live' for a good period of time when ignition is turned off;  and also doesn't go off/on when the engine is cranked / started.

 

Lots of modern vehicles have a mechanism to power down ancillary systems when the ignition is off after a period of inactivity to preserve battery charge.  (Think car radio going off after an hour)... 

I think it's been reported before that pin 9 'goes off' after a time and can't be used as a backup for a leisure battery like it could 'in the good old days' on some towcars.

 

Volvo generally have a good rep for knowing about caravanning and towbar wiring... so it would be unusual for them to get it wrong?

Edited by Rodders53
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I have a 2019 XC60 and found that the permanent live on pin 9 will turn off  a few minutes after switching the car off. 

According to the manual, it is possible to change this to be always on, but have not yet found the relevant settings screen. 

IMO as long as it comes on and stays on for the duration of any tow (Which it does) then it’s acceptable functionality 

Edited by Lost in the wilderness
Contex error
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Problem is, if the load of an ATC goes through a relay it may cause the relay to malfunction.

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9 minutes ago, MalH said:

Problem is, if the load of an ATC goes through a relay it may cause the relay to malfunction.

????

Perhaps, if said relay is not properly specified for the load to be carried.  But a relay in itself should be no more of an issue than a fuse (in that there will be some contact resistances and possibility of voltage drops).  This will be a main cutout relay from a major vehicle maker not a dodgy small thing from a not very good towbar technician.

 

I suspect your 'bitter experience' (has it been documented on this forum?) will be down to non OEM wiring looms etc.,. 

 

Oh yep... 

https://www.caravantalk.co.uk/community/topic/69531-atc-led-light/?tab=comments#comment-720609

 

T

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I have a 2019 XC60 and have only towed to have a service so far but away next week, ATC supply doesn't seem to operate in quite the same way as the previous Merc (that switched off after six hours). The manual states and I quote  "When the engine is switched off, the constant battery to the trailer connector can be switched off automatically so as not to drain the starter battery" its the word can which is a bit confusing as I don`t recall seeing a choice either.

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My V 70 is also 2013, so my wiring would be very similar if not the same. Mine has a 13 pin Volvo fitted tow bar also.

 

My pin 9 is perminant.  I have no idea if it goes off after a given time, but I don’t think so as it is live each time I connect the van.  However I will have recently moved the car.

 

I would guest you ask at your Volvo dealer, it My have been wired incorectly.  

 

One thing you you don’t want is the ATC going off, and worse back on, (as this applies the brakes during the test sequence).

 

John

Volvo V70 D3 SE (was Peugeot 4007, SsangYong Korando), Pulling a Lunar Clubman SI 2015. If you are depressed, you are living in the past. If you are anxious, you are living in the future. If you are at peace, you are living in the present.

 

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Thank you for your comments.

I suppose the safest way is for me to get the wiring checked out by a towbar specialist.  I think that my main Volvo dealer, where I got the car from, contracts towbar work out anyway.

Just out of interest can somebody explain to me, in fairly non technical terms, why the ATC connection has to be a direct supply from the battery as I had assumed that being on with the ignition would have been good enough.

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5 minutes ago, bigbilly said:

Thank you for your comments.

I suppose the safest way is for me to get the wiring checked out by a towbar specialist.  I think that my main Volvo dealer, where I got the car from, contracts towbar work out anyway.

Just out of interest can somebody explain to me, in fairly non technical terms, why the ATC connection has to be a direct supply from the battery as I had assumed that being on with the ignition would have been good enough.

The two supplies from your car are  permanent and "ign" controlled. Although with most cars the ign controlled circuit is dependent on the engine actually running, so will actually be an intermittent supply if you've got stop/start enabled and possbly even when the engine is just idling if it's voltage controlled.

 

As JC says above the unit self tests every time power is applied so you really only want to do it once when you couple up the van rather than starting the engine first and then having the thing self test it'self everytime you stop at a set of traffic lights.

 

Furthermore the ign supply is the one that supplies the fridge so has a pretty heavy load on it already and the additional current drawn by the ATC when it operates may well drop the voltage too low for the ATC to operate reliably, so possibly negating it's effectiveness.

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You need it live as if the ATC memory fills you need to leave it connected to the car without ignition switched on for minimum 12 hours to clear and to reset itself.

Edited by birdman101
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As per Rodders post above, the 13 pin wiring harnesses that are often fitted do not contain the extra pin 9 wiring, fuse etc for ATC,  (I had this problem myself). As outlined, it requires quite a chunky wire to be run through the car from the towing socket, through the bulkhead direct to the battery via a 20 Amp fuse.

 

Towbar installers often take the easier and cheapest option of doing all the work in the boot and not to bother fitting this permanent supply and earth as not everyone has ATC, they can then charge a bit more for the extra work involved.

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14 hours ago, compact said:

I have a 2019 XC60 and have only towed to have a service so far but away next week, ATC supply doesn't seem to operate in quite the same way as the previous Merc (that switched off after six hours). The manual states and I quote  "When the engine is switched off, the constant battery to the trailer connector can be switched off automatically so as not to drain the starter battery" its the word can which is a bit confusing as I don`t recall seeing a choice either.

That seems like a Dealer Programming option to me... worth asking them or HQ customer services!

Better towbar fitters may be able to do it with the right diagnostic kits...

 

Beejay needs to check/read the car manual to see if there's a similar statement?

 

I'd really recommend that Beejay checks out what actually happens on pin 9:

when all off overnight

when IGN on

when 'starting' engine

when idling

when engine stopped, IGN off and left....  timing to see if/when pin 9 12V goes off

finally when vehicle locked (in case it's not simply IGN controlled).

 

THEN back to dealer to discuss what can be done (if anything is needed)? 

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Had my BMW for 18 months and always considered the ATC to be on a permanent 12v supply. I've never noticed anything to suggest the contrary.

Until this week.

Collecting the van from storage, I had a couple of minor jobs to do, so abandoned the car in the middle of the roadway (it is a BMW, so its OK to park anywhere!).

Pulled the van out on the movers and hitched up about 45 minutes later - No ATC.

Out with the meter and no voltage on the socket.

Wifey then opens the car door, which of course wakes up the car.

Cue ATC self test and green light.

 

Every day's a school day.

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I don't see an issue provided you don't turn off the ignition.

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15 hours ago, AlwynMike said:

Had my BMW for 18 months and always considered the ATC to be on a permanent 12v supply. I've never noticed anything to suggest the contrary.

Until this week.

Collecting the van from storage, I had a couple of minor jobs to do, so abandoned the car in the middle of the roadway (it is a BMW, so its OK to park anywhere!).

Pulled the van out on the movers and hitched up about 45 minutes later - No ATC.

Out with the meter and no voltage on the socket.

Wifey then opens the car door, which of course wakes up the car.

Cue ATC self test and green light.

 

Every day's a school day.

When the car is asleep does the car alarm activate when the caravan is unplugged?

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11 minutes ago, Tradewinds said:

When the car is asleep does the car alarm activate when the caravan is unplugged?

I've never left it long enough to find out, sorry.

In fact I can't remember ever locking the car with caravan plugged in!

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Thank you for all your comments.

I took my XC60 to a reputable towcar company yesterday and they thought it was fine going throught the ignition and said that most manufacturers these days supply dedicated wiring looms and specific wiring and calibration instructions and confirmed that mine was a genuine Volvo supplied towball and wiring harness.  Feel a bit happier now.

Just have to see how it tows !

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I see no reason why mine should be any different to yours but mine appears to be perminant live.

 

I say ‘appears’ because I will always have had the ignition on to position the car prior to hitching up.  But it could easily have been standing with the ignition off for 5 min.  But pin 9 is live.  Possible it’s on a timer so it just appears to be perminant.

 

John

Volvo V70 D3 SE (was Peugeot 4007, SsangYong Korando), Pulling a Lunar Clubman SI 2015. If you are depressed, you are living in the past. If you are anxious, you are living in the future. If you are at peace, you are living in the present.

 

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3 hours ago, bigbilly said:

Thank you for all your comments.

I took my XC60 to a reputable towcar company yesterday and they thought it was fine going throught the ignition and said that most manufacturers these days supply dedicated wiring looms and specific wiring and calibration instructions and confirmed that mine was a genuine Volvo supplied towball and wiring harness.  Feel a bit happier now.

Just have to see how it tows !

I don't understand how they could say it is ok to go through the ignition.

Unless there are two relays one controlling each pin, one relay operating at a lower voltage to keep atc active.

If for example you are at traffic lights, and car voltage is low, then the relay cuts power to the caravan. This would cut power to the atc and when you pull away the voltage increases and the relay makes. The atc then performs the start up checking procedure.

Am I missing something???

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16 minutes ago, Tradewinds said:

I don't understand how they could say it is ok to go through the ignition.

Unless there are two relays one controlling each pin, one relay operating at a lower voltage to keep atc active.

If for example you are at traffic lights, and car voltage is low, then the relay cuts power to the caravan. This would cut power to the atc and when you pull away the voltage increases and the relay makes. The atc then performs the start up checking procedure.

Am I missing something???

Before I had an ATC fitted by AlKo I was told that I had to have a permanent live feed.  I assisted a friend, who is an auto electrician, to install the feed. It took half a day to install as the cable was fed through the bulkhead and inside the bodywork.

I always connect the 12S plug to vehicle when the ignition is off as I can then hear the ATC going through the set up drill..

The towing vehicle is a VW 2004 Passat estate, not one of the new fangled stop start models.

The first check that was made by Alko, before the vehicle was taken to the workshop, was the live feed with ignition in the off position.

I also find it difficult to understand that an ATC would work with an intermittent feed.

Edited by DeeTee
added sentence
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1 hour ago, Tradewinds said:

I don't understand how they could say it is ok to go through the ignition.

Unless there are two relays one controlling each pin, one relay operating at a lower voltage to keep atc active.

If for example you are at traffic lights, and car voltage is low, then the relay cuts power to the caravan. This would cut power to the atc and when you pull away the voltage increases and the relay makes. The atc then performs the start up checking procedure.

Am I missing something???

 

Its not complicated while ever the ignition is on then a relay could be energised to supply the feed for ATC/charging.

 

The fridge supply will still be voltage sensitive using a different relay.

 

 

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1 hour ago, Tradewinds said:

If for example you are at traffic lights, and car voltage is low, then the relay cuts power to the caravan. This would cut power to the atc and when you pull away the voltage increases and the relay makes. The atc then performs the start up checking procedure.

Am I missing something???

 

I think so.  On my 2017 XC60 the ‘stop-start’ disables when you plug in a c’van/trailer so that the ATC doesn’t keep going through startup procedure, my previous Audi A5 did exactly the same as do, I believe, most if not all recent Euro5 and 6 cars.

 

The fancy “alternator tricks” are also disabled so the voltage remains high when idling and the fridge supply is uninterrupted.

 

On both XC60 and A5 the ATC remains live when stopped and  ignition off, certainly for duration of refuelling/comfort break etc stops but must admit I haven’t checked if it does for an extended period

DrBob

Edited by DrBob
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48 minutes ago, DrBob said:

 

 

On both XC60 and A5 the ATC remains live when stopped and  ignition off, certainly for duration of refuelling/comfort break etc stops but must admit I haven’t checked if it does for an extended period

DrBob

My VW Tiguan is not live until the caravan is plugged in then pin 9 "Switches On" and ATC self checks. As yours does, my ATC remains active when stopped at Mway services.

Pin 10 is definitely switched and the fridge does run when the car is running.

I will have to try and locate more information on this, just to satisfy my curiosity. 

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