Just recently purchased 4yr old Sprite Major 6 and have a perculiar issue with fuses blowing for the L/H side lights, discovered on our first trip out with it.
Basically, the L/H side lights kept blowing the fuse in the caravan when they are switched on in the car.
I did some basic checks on the caravan bulbs etc, all seemed good. I then tested WITHOUT the car hitched up for ease of access and the lights all worked fine.
I then created a connection between the car and van chassis with a spare bit of wire and again the fuse blows.
So, I'm in a position where if I am hitched the fuse for one light circuit blows and if I am not hitched it all works fine.
Would anyhone have any opinion where to start trouble shooting???? The one observation I made is that the on the caravan electrical connector all the other lights were a closed circuit in relation to the white common ground, apart from my troublesome L/H indicator which was an open circuit.
Many thanks for any ideas.
Chris
If I connect the black cable to the caravan (but do not hitch up) all the side lights work absolutely fine.
Sounds like someone has wired something positive earth instead of negative earth...
Pin 3 should be earthed to chassis on car, on the caravan pin 3 should go to the neutral side of the lights and as far as I'm aware is never earthed to the caravan chassis.
Something to check, have any of the light terminals been earthed to the caravan chassis?
------------- Caravanning is a way of getting a cheap holiday out of an expensive hobby
To test both caravan connection sockets, you need to arm yourself with a 12 volt bulb with hook-up leads. One of those 12 volt electrical test screwdrivers is ideal. If the crocodile clip won't reach far enough into the socket to make contact, simply clip a bent paper-clip into the jaws.
On both 12N and 12S sockets, pins 1 to 6 are numbered clockwise from the top (pin 1 = 12 o'clock, pin 2 = 2 o'clock... pin 6 = 10 o'clock.) Pin 7 is the centre pin. (See the following photos)
12n Socket:
For the 12N road lighting (black) socket, you'll either need an assistant or some way of wedging the brake pedal so that you can make the brake lights stay on.
The pins to test are as follows:
1 and 3 - flashes in time with the LH indicator.
2 and 3 - lights only when rear fogs lights are turned on [1].
4 and 3 - flashes in time with RH indicator.
5 and 3 - lights when side lights (or right hand parking lights) are on.
6 and 3 - lights when brake pedal is pressed (with ignition on if needed).
7 and 3 - lights when side lights (or left hand parking lights) are on.
12s Socket:
The 12S (white or grey) socket should behave as follows:
Pins 1 and 3 - lights only when reversing lights are on (reverse) [2].
Pins 2 and 3 - lights only when engine is running (charge) [3] & [4].
Pins 4 and 3 - always lights (permanent live).
Pins 6 and 3 - lights only when engine is running (fridge) [4].
Pins 4 and 7 - always lights (permanent live) [5].
Footnotes: [1] If the vehicle has only ever towed small trailers, then the original owner may not have bothered with the rear fog connection. This is highly unlikely if you also have the 12S socket. If this is the case though, you do need to get this rectified before towing a caravan. [2] Many people don't bother to wire up the reversing lights, so don't be surprised if these don't work! It's up to you whether you get them fixed, and as far as I'm aware, they're not legally required. [3] A new method of battery charging wiring means that pin 2 on the 12S may not operate as described (i.e. it's always 'dead.') If this is the case, then you will probably be perfectly fine with a modern (late 1998 onwards) caravan but will need to get this resolved if you want to charge the battery in an older model. [4] Depending on how the switched supply is sourced, you may or may not get a reading from 12S pins 2-3 and 6-3 with the ignition on but the engine not running. [5] This tests that there is a ground connection on pin 7 - required for caravans produced after mid 1999. Without this connection, the fridges in these late model caravans will not run off 12 volts. For older caravans, this is not required.
------------- the only silly question is the one you do not ask.
So, PIN 3 is earthed to the chassis on the car, no issues there.
I buzzed out all the different lights against the PIN 3 on the van end of the plug and was getting around 2 ohms resistance for each lighting circuit and the circuits all work when plugged into an unhitched car. So, good blubs and no short circuits.
I then checked out resistance between PIN3 on the van end of the plug and van chassis - I was getting around 2.8 ohms resistance there and similar readings when I tested each lighting circuit against the caravan chassis.
Ah-ha!! I thought I could be getting somewhere now as it seems the neutral side of the lights is incorrectly earthed to the caravan chassis.
So, I checked the old caravan next to me in storage an got the same results :-( Maybe not found the issue yet...
However, I did replicate the issue with a different car so I am now atleast isolating the fault down to the caravan.....
Check for a voltage between caravan hitch and car chassis
Check also for a short between pin 7 and the caravan chassis
Check the cables serving the right hand lighting - front, rear, markers (if you have them) and number plate light especially where they come through the caravan skin.
Also check the 7 core cable where it is clipped to the chassis
Take all the bulbs out on the left hand side and the number plate lights does the fuse still blow?
------------- Caravanning is a way of getting a cheap holiday out of an expensive hobby
hi there we had a similar problem to this and turned out to be that when someone(me) screwed the number plate on i had gone through the cable for the back lights giving a short circuit
To close down this thread it was indeed damaged wiring on the caravan causing the issue.
The dealer who looked at it under warranty also replaced the TV signal booster box! I can only guess the aeriel cable and my lighting cables somehow got mangled/damaged in the same cable harness. Will have a nose around at the repair when I get it back out of interest.
All fixed and thanks for the help isolating this unusual issue from the posters here.
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Topic: Blowing fuses when hitched to car
