Re: Quality of towbar install

by mikeelawson Fri Sep 08, 2023 6:37 am

Coming back to the original post. AS and Sargent came back and confirmed the VL5 does not connect into CAMBUS of the vehicle so the install back to cab is correct. I have tidied up the cables, put the grease mentioned around the block and put amalgamating tape around. Also I have changed the towball so it is now 20mm further out, m16 high tensile bolts and locking washers. 300 mile trip this week and all seems well.

Regards,

BOOMEL

by Caraman Fri Sep 08, 2023 6:56 am

mikeelawson wrote:Coming back to the original post. AS and Sargent came back and confirmed the VL5 does not connect into CAMBUS of the vehicle so the install back to cab is correct. .......

I'm not entirely sure what you mean by "...install back to the cab is correct". Surely it is correct to connect the 13S or 12N socket to the VLM5 provided by Sargent for this purpose but there is no harm in not using the VLM5 other than additional expense and connections.

by mikeelawson Fri Sep 08, 2023 9:13 pm

Caraman wrote:
I'm not entirely sure what you mean by "...install back to the cab is correct". Surely it is correct to connect the 13S or 12N socket to the VLM5 provided by Sargent for this purpose but there is no harm in not using the VLM5 other than additional expense and connections.

The vl5 does not connect to vehicle CAMBUS so you will not be notified on dashboard if light on trailer board does not work.

Regards,

Boomel

by Caraman Sat Sep 09, 2023 7:15 am

mikeelawson wrote:

The vl5 does not connect to vehicle CAMBUS so you will not be notified on dashboard if light on trailer board does not work.

Regards,

Boomel

If you read the VLM5 User Guide which PLOUGHIN posted you will see that the indicators are covered:

"The VLM5 is an electronic module that is used in many motorhomes to control the rear LED road lighting. The unit includes monitoring of the motorhome rear direction indicators so that if / when a failure occurs this is shown on the vehicle dashboard (and by a flashing indicator on the VLM5 unit).
The VLM5 also includes the facility to connect an optional towing harness to provide a 13-pin socket for connection to a light board, trailer or caravan. When this socket is being used the direction indicator monitoring is extended to cover the device / vehicle being towed."

I'm not sure what happens if any of the other rear lights fail on the motorhome - presumably nothing? When I used to tow a caravan my wife always carried out a visual check of all the rear lights before we set off. We started doing the same with the lighting board on the motorhome but tend not to now. If there was a problem it was usually the connector not the bulbs and I now only use a 13pin connector.

by mikeelawson Sun Sep 10, 2023 6:31 am

Thanks read that, I gues I am referring to AS and Sargent statement only that it does not connect into CAMBUS

Regards

Boomel

by Caraman Sun Sep 10, 2023 7:37 am

I confess to a limited understanding of CAMBUS but when I get the opportunity I will plug my lighting board in (to the VLM5) and remove each of its bulbs in turn to see what dashboard effect it has. The effect should be the same for the motorhome's rear lights that are also connected to the VLM5. A simple experiment that anyone can do and will be informative.

by inspiredron Sun Sep 10, 2023 2:09 pm

Another potential issue with trailer electrics which used to crop up regularly when I had caravan was a poor earth connection, either at the 7 pin plug (that dates my caravan experience!) or in the internal trailer electrics. It taught me the importance of always checking two types of trailer lighting simultaneously. If you check brake lights or flashers individually you may not realise that they are operating at a reduced brightness if the earth return is lacking. I followed a friend's caravan once and be signalled left - the left indicator flashed. When he braked for the turn the left indicator extinguished while both right indicator and brake lights flashed in time with each other. Unused circuits were being used as the earth return via another bulb, which lit if passing enough current.
What I have recounted applies only to conventional filament bulbs on a non CANBUS equipped vehicle. I don't know what would happen in a modern vehicle with LEDs and/or CANBUS or how the fault would be reported.

by gassygassy Sun Sep 10, 2023 8:01 pm

Just to be picky, it is CANbus, see here for lots of helpful details and a simple tutorial. Well, it says it is simple.
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It is a system to send streams of data along two wires, and a microprocessor at the other end (eg in the gearbox) communicates with The Computer That Must Be Obeyed - otherwise it throws a hissy fit and illuminates a light on the dashboard. Then a garage gorilla changes the £500 component that his diagnostic computer says is faulty, then the gorilla has to find someone with two brain cells who can mis-interpret what the diagnostics says and change the actual faulty part or mend the corroded connector or clean the sensor that has got a bit bunged up.
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by gassygassy Sun Sep 10, 2023 8:15 pm

inspiredron wrote:Another potential issue with trailer electrics which used to crop up regularly when I had caravan was a poor earth connection, either at the 7 pin plug (that dates my caravan experience!) or in the internal trailer electrics. ............

Quite true. In the 1980s I was deeply investigating caravan electrics to see if it was possible to make a wiring loom from aluminium wires to reduce the weight of the caravan because one of the manufacturers asked me to. ( the answer is no). I investigated the British Standard and there wasn't a single caravan manufacturer adhering to its earth return (or chassis -12v) cable specification. Consider the 10A that a fridge takes, plus up to 7A at one time for the rear lights so 17A have to run from the car to the caravan and back to the car chassis. The various lights and appliances each have their own +12v wire, but all of them have to send their return current back to the car chassis along one (usually white) wire so it has to be quite thick. The metal connection of the towball is not to be trusted, it may well be covered in grease, and generally speaking the long run of wiring drops the voltage somewhat. I think the 13 pin plug has two white return wires - I'm not sure as I haven't wired one, but this will help the lights and fridge and so on to work properly.
The wiring is the most common reason why fridges don't work on 12v. High resistance joints, long wiring run and too-thin wires are used. A lot of people say a fridge won't cool from startup on 12v but they will, if they have 12v or preferably 12.5v. If they have 10.8v they won't.

by Caraman Mon Sep 11, 2023 8:10 am

12N and 13 Pin wiring showed here:

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For a lighting board only pins 1 to 7 are used, pin 3 white being the common earth and fitted with a 2.5mm wire rather than 1.5mm for the rest. For caravan towing only, so not applicable here, two additional 2.5mm earths are provided (pin 11 white/black & pin 13 white/red).

by Avontourist Mon Sep 11, 2023 9:29 am

cheap lighting boards can have 7 wires all the same size and not the heavy earth wire, usually they have poor connection to the bulb holders which can corrode after a while .
I am surprised that AS don't fit or offer the socket wiring when they fit a bike rack mounting that needs a lighting board to use. .