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UKmitch86

Road lights issue via 13pin - no brakes or sidelights.

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Hi all.

 

I've got a 2014 Swift Challenger. It's been serviced at start of June. We also have a new car with a new towbar installation, universal, not integrated into ECU. Both caravan and car had their electrical connections tested and proven at point of service and point of install respectively.

 

Upon connecting the new car to the caravan, indicators, hazards and reversing lamps are all fine on the caravan and car.

 

When pressing the brakes, nothing happens. When turning the sidelights on, the sidelights blink momentarily then stay off.

 

When the van is disconnected, the car had lost passenger-side side light and brake lights. Turn the car off and on again, and the car was fine.

 

I'm vaguely technical but not familiar with the caravan and car systems - is it correct that the car powers the caravan's lamps? Or does the Caravan have relays installed that use its own battery via said relay contacts?

 

My plan is to first test the car by using a multimeter in the female sockets to make sure the car is spitting out voltage on the right pins.

 

Can anyone lend any words of advice?

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Go visit a Swift Group dealer, it is possible that your new car does not suit a VLM board fitted to your caravan.

The VLM board is a device to enable the LED road lights on the van to work properly with the towbar electronics fitted to cars with filament bulbs. There are several different VLM boards to suit different car electronics.

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9 minutes ago, Stevan said:

Go visit a Swift Group dealer, it is possible that your new car does not suit a VLM board fitted to your caravan.

The VLM board is a device to enable the LED road lights on the van to work properly with the towbar electronics fitted to cars with filament bulbs. There are several different VLM boards to suit different car electronics.

 

Thanks Stevan - tell me more about this board? What does it do in the caravan? I thought 13pin electrics were standard.

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13 pin electrics are standard - or should be.

But Swift choose to use LED lights which can and do upset many car electric interfaces because of the relatively small current they consume.

The VLM unit is to interface the LED lights with car electrics that generally are set up for filament lamps.

As Stevan says, there are a number of VLM units around,  and yours may be incompatible with your car. 

 

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Posted (edited)

I've just spoken to Sargent Electrical technical and they're of the opinion that the van isn't new enough to have LEDs, so a VLM box isn't going to a fix. Also, with the reversing and indicators working, the brakes and sidelights ought to be fine (if it's to do with resistance of the bulbs).

 

 

4 minutes ago, AlwynMike said:

13 pin electrics are standard - or should be.

But Swift choose to use LED lights which can and do upset many car electric interfaces because of the relatively small current they consume.

The VLM unit is to interface the LED lights with car electrics that generally are set up for filament lamps.

As Stevan says, there are a number of VLM units around,  and yours may be incompatible with your car. 

 

 

I should take a look for a VLM box I guess - if Swift fitted one, that'd tell me I've definitely got LEDs and not filaments.

 

Where might I find the VLM box in the van?

Edited by UKmitch86

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Do you know anyone with a trailer/another caravan?  That will eliminate the car if they work fine with another trailer, or if you know someone with a car equipped for towing, try that on your caravan.  Hopefully eliminating one or the other will narrow things down a bit (unless it's a compatibility issue with them both).

 

I'm not saying that it's the car wiring, but I have heard of issues with modern car systems and universal trailer electrics when the additional load of a caravan road lights are applied.

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1 minute ago, GaryB1969 said:

Do you know anyone with a trailer/another caravan?  That will eliminate the car if they work fine with another trailer, or if you know someone with a car equipped for towing, try that on your caravan.  Hopefully eliminating one or the other will narrow things down a bit (unless it's a compatibility issue with them both).

 

I'm not saying that it's the car wiring, but I have heard of issues with modern car systems and universal trailer electrics when the additional load of a caravan road lights are applied.

 

I've got a helper available on Saturday with another 13pin socket on a car.

 

My thoughts on another van were to see if another caravanner in the storage yard would mind me clipping up the socket.

 

Do you know where the lights are terminated in the van? I need to make sure the voltage gets to the lamps. If I can prove the 13pin van plug is passing the voltage through to the distribution block, I can rule out the socket.

 

 

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Caravans don’t use the “Earth return” system that cars do (no metal bodywork) so each lamp has a feed and return both of which are wired to the 13 pin plug. 

 

As it was OK at service time and it’s not OK now what’s the one thing that’s changed! Your tow car! That’s where I would start looking. 

 

Andy

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This sounds like one for the towbar fitters to be asked about.  They may have encountered a similar issue before?  BUT the car ECU is sensing an overload and needs a power reboot to fix.  That suggests the aftermarket kit is not doing it's intended job of interfacing to caravan lights...  

 

Modern cars are frequently best with dedicated electronics / wiring and ECU programming (via dealer if necessary).  You profile says "TBC" for towcar... make, model and year would likely help someone in the know?

 

Swift group vans tend to have the 12-core cable enter on the offside front bulkhead and a connector / connectors with fuse-board there (maybe with the habitation relays on a PCB, too).

Check out the manuals/technical handbooks - Swift wiring diagrams are usually pretty comprehensive.  https://www.swiftgroup.co.uk/owners/handbooks   

They BTW confirm the lamps are normal filament on 2014 MY - unless changed by a previous owner for some reason?

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33 minutes ago, UKmitch86 said:

 

I've got a helper available on Saturday with another 13pin socket on a car.

 

My thoughts on another van were to see if another caravanner in the storage yard would mind me clipping up the socket.

 

Do you know where the lights are terminated in the van? I need to make sure the voltage gets to the lamps. If I can prove the 13pin van plug is passing the voltage through to the distribution block, I can rule out the socket.

 

 

 

Quite a few permutations on where the ' distribution block ' is on caravans and even on the same makers different models.

 

Have a look under the caravan to see where the lighting cable enters, usually at the front and if you are lucky you may find a junction block and possibly a bank of fuses for the trailer lights, occasionally there will also be a fuse for the caravan 12v + feed and one for the charger, there may be a habitation there as well in the same area.

 

Failing them being there it will be a game of hunt the thimble, you will have to follow the cable till you come to the termination / distribution block,

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Posted (edited)
57 minutes ago, UKmitch86 said:

I've just spoken to Sargent Electrical technical and they're of the opinion that the van isn't new enough to have LEDs, so a VLM box isn't going to a fix. Also, with the reversing and indicators working, the brakes and sidelights ought to be fine (if it's to do with resistance of the bulbs).

 

 

 

I should take a look for a VLM box I guess - if Swift fitted one, that'd tell me I've definitely got LEDs and not filaments.

 

Where might I find the VLM box in the van?

Swift don't fit VLM boxes, dealers or owners do. If the caravan does not have LED road lights it is unlikely to have been fitted with a VLM box because there would not have been any compatability issues.

It sounds like the issue is with your new car and incompatibility with the universal tow bar wiring.

On Swift models the road lighting termination will be under either the left or right front seating on the front bulkhead. If a VLM box was fitted it will be next to the termination box as they are simple plug & play devices.

Edited by Legal Eagle

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Posted (edited)

The ‘universal’ wiring harness most likely the problem. On modern cars with canbus systems it doesn’t take much to upset the body control module. The fact that the car lights go doolally when you connect up then reset after an ignition key cycle once disconnected would bear this out. 

Ive always advocated using the car manufacturers own wiring harness for the towbar.   A universal system will probably have been hooked into the cars indicators and brake lights with the spawn of the devil, scotchlok connectors. You just can’t do that with new car electrics, it’s asking for trouble particularly on PSA vehicles. 

Edited by Tuningdrew

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Posted (edited)

Just a quick update.

After trying with a Ford Kuga (Ford fitted electrics (who I've learnt prefer not to interface with the ECU)) the same problems exist although their nature has changed a little;

  1. When sidelights are turned on;
    1. all marker lamps come on as they should
    2. passenger side brake light is on
    3. driver side sidelight is dull
  2. When brakes are pressed;
    1. all marker lamps come on faintly
    2. left brake light comes on bright
    3. right brake/side is duller than before.

Given a second car is having similar trouble, I've used a caravan chronicles guide to checking the Qashqai's install. All checked out OK. I've been out to an NCC workshop this morning who kindly spoke to me at length and connected a test box of their own which also showed no fault in the Qashqai.

 

The working principle has now got to be;

  1. Work through the caravan circuits starting at the 13pin plug (this is going to have to get cut off, I can't get into it for love nor money).
  2. Seems reasonable that the Kuga might have slightly higher tolerance for short circuits and voltage coming from there is simply being used to drive more lamps and the Kuga doesn't feel the need to self-protect. It does tally that the QQ flicks the sidelights on, then immediately off again as if a breaker is being tripped.

 

The service guys agree it sounds like caravan now so have offered to come fit a new plug.

 

 

Edited by UKmitch86

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How about removing the Leisure battery, getting a couple of fly leads and, using the LB, testing each caravan lighting circuit at a time? That could save you a lot of time/effort.

 

Andy

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As Andy says, an initial  quick way without chopping the the plug  would be to makeup a couple of jumper leads with crocodile clips on the end, the wire only needs to be small dia, similar to the lighting wiring, strip a bit of insulation from the end opposite the crocodile and twist to form a probe, then along with a diagram of the plug pins LOOKING INTO THE PINS, from the outside of the plug , most important,  and using a plug pin diagram and an observer, put your - probe on the plug  - then selectively , noting the pins for each light touch the + probe to each lighting pin and see what your observer says.

 

This test is far easier if you can gain access to the inside of the plug.

 

NOTE OF CAUTION, DONT TOUCH BOTH PROBES TOGETHER< NOTHING WILL BLOW UP  BUT YOU WILL GET A FEW SPARKS AND POSSIBLY MELT YOUR PROBE WIRES

 

The symptoms you have described  other lights coming on dimly etc usually point a poor neutral connection somewhere, usually in a bulb holder where the  - connections at the bulb is corroded , when power is applied to that bulb it finds a - return via the filament of a bulb with  a good - connection, consequently both bulbs will light at 1/2 brilliance.

 

One thing about the observations you have made is that you appear to have bulbs nor led's .

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As soon as you have bulbs interacting with each other it shouts earth problems to me. 
 

  • I agree completely 1

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What you have described sounds like a classic “bad earth” fault. 
Caravans don’t have an “earth “  as such, but use dedicated return wiring. 
I would start at the rear lights, inspect all the terminations, making sure they are clean and tight. 
Then it’s a case of following the wires until you find a junction point, and repeat the inspection. Keep going until you get to the plug

 

 

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17 hours ago, Tuningdrew said:

As soon as you have bulbs interacting with each other it shouts earth problems to me. 
 

 

I agree 100%. Try removing the bulbs one at a time as the symptoms usually indicate that one bulb is earthing through the filament of another.

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I'm going to disagree with almost everything that's been written here.  The issue is with the use of  "universal" tow bar wiring on the car.

 

Canbus electrics in the car are FAR cleverer and work to protect the electrical system of the car ( I will describe an example with my van later)  and the Control Modules will detect what is going on, and the symptoms you describe of the sidelights coming on briefly almost certainly prove the case.  When you cut into the wiring harness in the car, and have incandescent bulbs of say 5w you potentially have 2 rear lights, and maybe 2 marker lights.   You will have added 20W, which equates to a current draw of something like 1.6 Amps (20/12)... The lights on the car will be LED and so the Control module is "expecting" to see say 0.5 A on the sidelight circuit, and shuts down the circuit (hence your sidelights flash on then off) in order to prevent any further increase in current and protect the wiring. 

 

How do I know this?  When I got my Bailey it came with 2 reversing lights and 2 rear fog lights.  All other lights worked fine. In discussion with the towbar fitter (I had a Vehicle Specific wiring module, albeit not the Ford one), he contacted the VSU manufacturer, who identified that their module was designed for single reversing and fog lights.  They provided suitably ballasted LED bulbs , problem fixed.

 

 

I'm afraid you're going to have to rip out the universal kit and replace with a Vehicle Specific kit. 

Edited by Guzzilazz
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On 01/07/2020 at 09:15, Guzzilazz said:

They provided suitably ballasted LED bulbs , problem fixed.

 

I'm afraid you're going to have to rip out the universal kit and replace with a Vehicle Specific kit. 

A good post Guzz which I think explains a similar problem I am having. The car expects to see a load in a soecific range and if the values are outside of set parameters there are problems.

 

However when you say 'rip out the universal kit', this may not be necessary if the bulbs are suitably ballasted as you mention in your post above. Taking this one step further, why ballast every bulb individually when it could be done once in the wiring harness where the 13 core wire terminates or else in the plug itself? This is what I plan to try, I don't need to dissipate 20w because my trailer module is already expecting to see a lower LED type load.

 

The OP is well advised to keep the 13 pin plug and socket which are far more reliable, this is not the problem. LED bulbs/canbus are the issue.

Edited by limecc

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3 minutes ago, limecc said:

Taking this one step further, why ballast every bulb individually when it could be done once in the wiring harness near the 13 pin plug terminated? This is what I plan to try, I don't need to dissipate 20w because my trailer module is already expecting to see a lower LED type load.

 

The OP is well advised to keep the 13 pin plug and socket which are far more reliable, this is not the problem. LED bulbs/canbus are the issue.

 

I dont think that will work. Each circuit is separately monitored by the canbus system (isn’t it?) so surely each circuit has to be treated individually??  

Happy to be proven wrong as I understand electrics pretty well but when it comes to  eletronics it’s voodoo to me :(

 

Andy

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28 minutes ago, Mr Plodd said:

 

I dont think that will work. Each circuit is separately monitored by the canbus system (isn’t it?) so surely each circuit has to be treated individually??  

Happy to be proven wrong as I understand electrics pretty well but when it comes to  eletronics it’s voodoo to me :(

 

Andy

Yes each circuit, left/right indicator, both sidelights and both brake lights would need a resistor to earth, so 6 circuits. Need to draw no more power for each circuit with a resistor than with filament bulbs had they been fitted.

 

I was suggesting ballasting in the cable because it might not be possible, for example in the marker lights because of physical space limitations.

Edited by limecc

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This has forked into 2 problems, the first of which has been resolved;

 

 

1. Faulty RHS brakelight. Was dim, thought it was wiring issue, turns out it was partially earthing. Bulb change cured brake light problems.

 

On 29/06/2020 at 15:08, Mr Plodd said:

 

How about removing the Leisure battery, getting a couple of fly leads and, using the LB, testing each caravan lighting circuit at a time? That could save you a lot of time/effort.

 

Andy

 

Hi Andy, thanks for this. The caravan servicing guy came back just a couple of hours ago. He found that the iffy dim RHS brakelight was nearing the point of blowing, but hadn't blown. He did this with a 12V battery and a box with switches on to energise each circuit. Everything played ball after the bulb was changed. He postulated that the failing bulb may have be leaking to earth, causing the car's signal from the brakes to bring the sidelights on dimly.

 

It doesn't matter whether the sidelights on the car are off, on, or dipped beam - the brake lights function on caravan AND car.

 

2. Faulty sidelights. Illuminating for a fraction of second, then off. Now suspect overload of Qashqai's LED supply.

 

After the above discovery, the car driver-side sidelight does not come on and the caravan sidelights flick on and off again. The car keeps its passenger side sidelight on. Restart the car without 13pin plug in, and all functions return.

 

On 01/07/2020 at 09:15, Guzzilazz said:

Truncated by UKmitch86;

How do I know this?  When I got my Bailey it came with 2 reversing lights and 2 rear fog lights.  All other lights worked fine. In discussion with the towbar fitter (I had a Vehicle Specific wiring module, albeit not the Ford one), he contacted the VSU manufacturer, who identified that their module was designed for single reversing and fog lights.  They provided suitably ballasted LED bulbs , problem fixed.

 

Hi Guzzilazz - I've reached this theory now myself before I read your post. What do you mean by "suitably ballasted LED bulbs"? I'm about to sum the power consumption on the two sidelight circuits. I expect to find it higher than the other functioning circuits.

I've not yet accepted the loom needs to come out - if after I've summed the power draw I find it higher than every other functioning circuit, then wiring schematic permitting I plan to remove the caravan filament marker lights temporarily to prove the car's overcurrent protection is kicking in. If this works (assuming I can cut the power sufficiently) then I plan to replace with LEDs on the caravan.

I could also get myself a little variable resistor and lay it across sidelight pin pairs and slowly increase to the point the car cuts the voltage. This would be the target max power input. It's a way to work out whether the move to LED marker lights could ever bring power consumption low enough.

 

On 29/06/2020 at 14:56, UKmitch86 said:
  1. Work through the caravan circuits starting at the 13pin plug (this is going to have to get cut off, I can't get into it for love nor money).
  2. Seems reasonable that the Kuga might have slightly higher tolerance for short circuits and voltage coming from there is simply being used to drive more lamps and the Kuga doesn't feel the need to self-protect. It does tally that the QQ flicks the sidelights on, then immediately off again as if a breaker is being tripped.

 

Having used a multimeter to prove each of the circuits is functioning on the car socket, I can confirm it is presenting voltage as it should. As I'm sure lots of us know, presenting voltage with no load isn't telling us it'll work with higher load, but it does prove the wiring is OK. I also took the car to an NCC approved workshop who offered to use their testbox - that showed the car was good. I've noticed that everyone's testboxes are simply LEDs hooked into the appropriate pin pairing. Nothing with high enough resistance from a group of filament bulbs to simulate the number of bulbs on a caravan.

 

 

Edited by UKmitch86

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On 25/06/2020 at 15:26, UKmitch86 said:

When turning the sidelights on, the sidelights blink momentarily then stay off.

Turn the car off and on again, and the car was fine.

Can anyone lend any words of advice?

I had the exact problem above. On the Audi, cycling the ignition was needed, on the BMW I had to replace the fuse.

 

Turns out the LED bulbs I was trying to fit in the front Britax marker lights had a different connection compared to the standard filament bulb and this was not easily noticed on casual inspection. In fact I had to remove the holder and see where the wires went before I realised what was happening.

Edited by limecc

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I had a similar problem with my Swift 2014. Very elusive but prove to be a small amount of water  in the 13 pin plug.  Only caused a short circuit when the plug was horizontal (i.e plugged in). Not apparent when being tested as the plug was held up.

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