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The vast difference in prices just goes to show the cons of modern cars with the CANbus wiring systems.

It dreads me to think what is going to happen to some of these cars as they get older and things start to go wrong with them and the cost of fixing them.

It used to be a case that a car was scrapped because the body rusted away or the engine blew up but it will soon be a case of a perfectly good car being scrapped because of an electrical fault in the ignition packs or similar and the owner not being able to afford to replace the part.

Quote: Originally posted by happybonzo on 01/3/2012The towbar for our Motorhome cost £600 because it had to be made as a "one off"

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The way to go imho is single 13pin electrics, not only does this integrate your trailer with the cars alarm, it also marries it to the car's onboard computer, via the Cambus interface, once fitted the system is coded to the car, either by fitter or car dealership.

The 13pin solution is more secure than 7pin connectors, as it's a twist push bayonet type fit.

Not to mention a neater finish than having two sockets on the towbar.

Quote: Originally posted by baggie73 on 04/3/2012Hi folks,

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I am currently looking to get a towbar fitted on my C4 grand Picasso , talking to various companies it seems that you need to ensure that the electrics need to come direct from the battery to ensure that the cars wiring loom is not compromised as this can cause electronic faults in the future. Just something to consider when getting prices. Average price I have been quoted is £250 for fixed bar and single electrics.
Does this sound about right?

Baggie, what was meant in "the elecrics from the battery" means is with  more modern car that has the bulb failure warning, etc the power for the trailer lights come direct from the battery but the signals for those lights come from the car lights using a "bypass relay" as the "signal" current is only small it will not affect the bulb out warning system.

When you put an indicator on a small current goes to the relay which allows a feed from the battery through the relay to the trailer indicator light. The relay has 7 signal input wires to connect to the car wiring, 7 outputs to go to the towbar wiring then a +ve and -ve connectors to bring power from the battery and the earth.

With a car like mine it has no bulb out warning nor alarm so does not need the bypass relay and you just link up the towbar wiring into the car light wiring feeds.

Quote: Originally posted by ST1100 on 04/3/2012

Baggie, what was meant in "the elecrics from the battery" means is with  more modern car that has the bulb failure warning, etc the power for the trailer lights come direct from the battery but the signals for those lights come from the car lights using a "bypass relay" as the "signal" current is only small it will not affect the bulb out warning system.

When you put an indicator on a small current goes to the relay which allows a feed from the battery through the relay to the trailer indicator light. The relay has 7 signal input wires to connect to the car wiring, 7 outputs to go to the towbar wiring then a +ve and -ve connectors to bring power from the battery and the earth.

With a car like mine it has no bulb out warning nor alarm so does not need the bypass relay and you just link up the towbar wiring into the car light wiring feeds.

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Quote: Originally posted by fatbloke28 on 05/3/2012

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my 20+ year old volvo has a bulb warning failure device an indicator buzzer doobry and an alarm and its plumbed into the wiring loom at the rear.
i would think if you have a grey socket as well as the black one perhaps then the grey socket would need a feed from the battery ?
mine just has a 7 pin black socket
perhaps in the 13 pin modern versions it has a pin for running the fridge similar to the grey socket but i would have though that would be already taken into consideration by the car maker?
i'l stick to my 20 year old car

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Unfortunatley for owners of cars with the "modern" style wiring, it's the 7 pin sockets that needs the extra "bypass relay" with its direct power supply from the battery as well as a supply for the 12S (fridge and caravan battery if fitted). The wiring on these "modern" cars are not power connectors but just a signal to the tail light to "flash" or "light" with seperate power going to the full unit seperately, supposedly to cut down on the bulk of the wiring. The 13 pin connector is just the 12N and 12S combined into one.

With cars like yours and mine, the wires to the lights carry the power switched by the controls on your steering column, etc and there is no problem connecting into these supplies to extra light, as long as the wires and fuses can handle the extra current (usually no problem).