diy towbar electrics

[karl_5082018]

hi, I have the "N" plug on the towbar of my car, How hard is it to wire in a "S" plug can it be done by a DIYer? has anyone seen instructions on the net so I can get some idea to what is involved.

thanks for any help

 

[rayc]

Karl, it is well within the capability of a competent DIYer who is familair with working on car electriocs. If you have any doubt as to your capabilities then it is best left to a tow bar fitter.

You can check wiring diagrams at www.towitall.co.uk/trailer_wiring/instructions.htm

 

[Rubix]

I have fitted tow-bars and electrics to my last two cars.

I would like to add, I don't (yet) own a caravan, but have a trailer with N and S electrics (for reversing lights and 12v for camping power.

The "N" socket is easy as it is only for the lights, using scotch-lock connectors.

The S socket can be a problem, as you need to find a permanent live (+12v) feed, and this may involve going to the battery. This is where my knowledge ends, as I don't know about how the fridge feed, and battery charge are connected, as you need relays so power is not used when the car ignition is off.

If you have any doubts, get it fitted professionaly. You don't want to get a flat car battery if it goes wrong.

 

[GStockton]

Scotchloks!I would really start to worry if I saw any one using these poor items. Proper auto electricians use solder and heatshrink for critical connections. Scotchloks cut into the copper wire and then later corrode! Beware!

 

[Rubix]

Scotchloks!I would really start to worry if I saw any one using these poor items. Proper auto electricians use solder and heatshrink for critical connections. Scotchloks cut into the copper wire and then later corrode! Beware!

G Stockton,

Well that is what towbar companies supply when they sell them. I have been given them by a small company, and Indespension. As they both fit themselves as well as sell them, I would be suprised if they didn't used then too.

But then I might be wrong, and as you said a "good auto electrician" should use a more secure method.

 

[rob_jax]

Agree about the 3M Scotchloks, they are just evil inventions designed to cause problems in the future.

The tow-bar installer should be using the correct tow-bar wiring loom for the car - which are supplied with the correct end connectors - and only fabricating a lead (using solder and shrink wrap) when the car manufacturer doesn't provide the connector in the car loom.

Karl - You would be best served by buying a 12S kit, with the relays, etc. prewired into the loom - or at least supplied with instructions of how to add them.

Installing the 12S socket will most probably require a 30 Amp feed wire to be run to the battery or fuse box - if you have a spare in the box - because the caravan fridge will draw a minimum of 10 amps and you also need to compensate for voltage drop on long runs of wire - so a thicker, higher current rated wire is needed for correct operation rather than the minimum specification.

Karl - any uncertainties - get a good autoelectrician to install the 12S socket.

Robert

 

[Rubix]

I stand corrected, my apologies. If there are any auto electric engineers out there who fit "properly" then well done.

Why is it these loom connectors you talk of, aren't supplied when you buy a DIY towbar kit ? I agree it would be much better than scotchlocks.

Do the connectors you talk of go between the existing plug and socket for the loom ? You will have to excuse my dim-ness (No my name isn't Tim, and No I'm not "Nice" Either)

Have a good weekend.

 

[GStockton]

Rubix It is all down to cost, for instance the cheap diy kit with 12n socket a bit of 7 core and scotchloks is about

 

[Rubix]

I don't deny that rob_jax does know what he is talking about, as I have mentioned in previous posts I am new to this game, but in my opinion (and it is MY opinion) any help is gratefully received. People who read these posts have the inteligence to sort the "wheat from the chaff" and so can make up their own minds.

Over the weekend I have been looking at how the battery charging relays work, and I "sense" that they are sensing relays detecting when the "12v" from the car battery is static (ie engine not running) and when it is being charged by the alternator (hence battery charging).

I thought it was highly complex to fit these as I assumed (wrongly) that you needed to run a wire from either the ignition system or fusebox, which in me experience (as limited as it is) is a pain in the preverbial.

Please (excuse) the (use of ) brackets, I feel it gets the (Point) over better.

Also excuse my warped sense of humour.

I await the barage of critisism and abuse (don't worry I have a thick skin)

 

[rob_jax]

When the man at "Tow-b-fabs" fitted the 13 pin electrics to my C270, he just plugged the complete harness into the socket in the boot - in one of the side panels.

And it's not a good idea to intercept (or twin) the wiring in a Mercedes or many other modern cars with "bulb failure" systems - you'll just start getting false warnings (or no warning) when a bulb fails. You need to find the manufacturer's socket - and use that.

The car socket for the 13 pin wiring loom already had the fridge circuit wiring in place - it's part of the ISO 11446 specification.

Robert