Towing electrics which cars NEED special harnesses.

[ericmark]

The fitting of a tow bracket is simple nuts and bolts and although some are easier than others, not too worried about that bit.

However with logic controllers doing some car lighting the electrics are no longer so simple, I am sure some time soon we will have just two wires from car to caravan with some bus system telling the caravan which lights to put on, not quite at that stage yet but moving in that direction.

So the question is what tow cars able to tow 1350 kg or more still have simple wiring systems?

 

[DaveHerns]

I would say nothing modern. Get a modern car and the manufacturer's harness. Don't you have to use the full manufacturers kit these days? MOTman will know.

 

[Doggit]

I'm speculating here, but the wiring harness should be a simple extension of the existing wiring, so it begs the question of where it gets joined to the car. All you're doing, is replicating the lights, brakes and indicators, so you should be able to just connect into the rear lights. The caveat is going to be where you have LED lights; but I can see where you're coming from with an electric car.

It's the modern reversing sensors that need automatic disabling when the trailer/caravan gets attached that needs thiinking about, without having to press the button on the dashboard when you start the engine.

 

[ericmark]

My wife wants to tow a large caravan, which already belongs to us, I am happy with a small caravan with also already belongs to us, my son has bought a second hand Jag with the tow ball and electrics already fitted, and able to do around 50 MPG however I don't have a spare £27k so need a compromise, the Kia is only rated 1250 max tow weight even with a 2 litre engine and to be frank plenty of power to tow, but today it seems it is what the manufacturer says not what it can physically do. My licence once had a HGV until I did not bother taking medical so has a silly limit on tow weight, can't remember how many ton, and my wife also has had a licence long enough for the weight of trailer not to be a problem. So I suppose I could tow with a Lada Niva 1600 as all wheel drive and before the manufacturer set the weight limit.

However using a carb these old work horses, are rather poor on fuel use. In the last 5 years fuel economy has moved on in leaps and bounds, however there are also cheats, even before VW got caught we had an Vauxhall and Toyota at the same time, both very small cars 1200 and 1300 the Toyota was automatic the Vauxhall was rated just slightly better than the Toyota for MPG, however the Toyota was much better than the Vauxhall in real life, a good 5 MPG better. I would alternate between the two North Wales to Heathrow when working there, so it was not one trip but many, so after VW got caught that has resulted in all VW cars being knocked off the list, and not too keen on Vauxhall.

So likely some far east car, even if engines made in Deeside Flintshire, but if it is going to cost £1000 for tow bar and electrics then this will make a difference to which is selected. At the moment running three cars, one is for my disabled mother, but this will drop to two, and I like to drive the same car every day when I can, so likely the replacement tow car will be used on a weekly basis, so want reasonable MPG. In real terms 50 MPG is what I want, below that hardly worth changing car.

This time I want it fully wired for towing, battery charging, fridge the lot, likely this will mean an inverter, things have moved on since the blocking diode and relay. And likely the inverter will be fitted in the caravan rather than the car. Hope is this will be my last car, by time I am 80 don't really think I should be driving.

 

[Astra99]

With Canbus, adding additional loads in the form of a trailer/caravan obligatory lighting will cause it to have a head-fit if done incorrectly! I have seen various different types of trailer lighting connection units (what is in the connecting boxes I have never bothered to look) but I would certainly go for the vehicle manufacturer's towbar electrics, or that supplied by one of the big towbar manufacturers.

 

[Doggit]

Sorry Eric, not wishing to be rude, but that last post was a complete waste of time and long winded. Towing weights are set by the manufacturers for safety limits for the brakes and handling, not only the engine power. Either decide on the best car for towing, or talk to a few local companies as to what they'd charge for each car in turn. And you can get 12V fridges.

 

[DaveHerns]

Yes and giving just brand names is no help. Jag "what " ? You don't need £27k for a 2nd hand Jag but is a Jag a good tow car? All modern cars have CANBUS (etc) electrics so the days of a bag of Scotchlocks to connect the electrics are well gone. What's the budget for the car?

 

[Doggit]

Wow, this threads opened up a hole in my car knowledge. I didn't understand the relevance of Astras comments until DaveH exeplified the CANBUS electrics. Having looked on the web, it looks like a whole new ball game. But I suspect that Eric doesn't have a CANBUS type car, although a replacement might well.

This was the link that I looked at, and as I suspected, it affects a lot of the handling systems that are on modern cars. I have an old trailer that was towed by a 54 plate Freelander, and it looks as though it wouldn't work with a new car without an intervening module, or a completely new trailer bar.

So the question is what tow cars able to tow 1350 kg or more still have simple wiring systems?

Sorry Eric, but I don't think there's a simple answer to this question. I feel you need to look at the car you want to tow with, check if it will tow the weight of the caravan and anciliaries that you want, and then look to see what the towing electric requirements are for the caravan you have.

 

[ericmark]

Thank you for link, the TSP is something new to me, I still have a Witter Mongoose a very old system. It would seem I really have no option but fit a dedicated kit.

 

[Doggit]

Not neccesarily; if you look through their website a bit more, you may find a module that'll convert the CANBUS system to the old style lights on the Mongoose.

 

[DaveHerns]

Do we know what Eric has or wants? I'm no expert on CANBUS systems but expect I'd find a socket somewhere to plug in the maker's wiring loom on my car so what you save on time you pay for in buying.

 

[Doggit]

What do you mean, do we know what Eric wants; even Eric doesn't know what he wants yet.

 

[Burnerman]

Most vehicles made after 2003 / 2004 will have a CANBUS system, and any extra loads on the wiring will almost certainly goose one of the body control modules that control that particular vehicle area.
So, relays are used in the tow bar electrical systems to prevent excess current draw.
Always go for the approved conversion loom if you are fitting a tow bar.
John

 

[AlanE]

Some new cars need the 'on-board computer' updated plus, if actually new, check how adding the tow-bar wiring with a non-approved, add on, wiring harness might affect the warranty.

 

[DaveHerns]

I think he needs a pre 2000 Range Rover/Discovery , use it for one holiday and then sell it before it goes wrong. You'd probably get one with full towing kit already on it.