I hooked up and connected electrics. The ATC connects and the light came on. I then went inside and turned the fridge on and selected battery-for towing. However it lasted a second or two and brought up a fault. The ATC light has gone off and the fuse had blown.
People saying the wiring could be wrong- its the 13pin type plug. I'm frustrated as going to Cornwall soon and wanted the fridge on.
Thanks in advance.
There should be a device in the car to only make the wire for fridge when towing live when the engine is running. It sounds like it is that device which is faulty.
What device it is depends on the car and the tow bar socket fitter etc.
Ok thankyou for that. Sounds like I need a towbar fitter then! I took it someone the cother day who found the fuse had gone. He kindly replaced it but I didn't get the impression he'd be able to help any further.
I agree with 664DaveS, It takes a substantial amount of current, 15A+ to activate the ATC, therefore it has it's own dedicated supply wire and fused directly from the towing car's battery. This is still an extra on most dedicated caravan supply kits and therefore often gets ignored because of the extra effort and time taken.
Maybe someone has tried to use the fridge supply instead, but it won't do the job. The ATC power should be on pin 9 of a modern 13 pin setup. The fridge power should be on pin 10 (switched on only when engine revs are about 1000rpm +)
Dave.
------------- Never argue with an idiot, they will drag you down to their level and beat you on experience.
Mark Twain.
Seem to recall some less than ideal practices from the days of 7 pin sockets where (12S) pin 4 (permanent supply) and pin 6 (fridge) were linked and supplied by a single source! 12S socket pin 4 originally only supplied caravan interior lights and maybe the leisure battery charger which was a relatively low amperage load. I suppose you have to take into account that ATC only came into existence in the later era of 7 pin sockets fitted as the standard (pre 2008, when 13 pin became the norm).
No details of OP's car, so wondering if the 13 pin socket fitted is an upgrade from previous 7 pin sockets and wiring has not been upgraded accordingly!
Even if a new fit 13 pin socket, towbar fitters can do some dubious installations, cutting corners as the permanent supply (13 pin, pin 9) can if done correctly involves running a new cable direct to the fuse box/battery, which they are too lazy to do as a lot of work! You often have to SPECIFICALLY instruct you want a FULLY wired socket and FULLY integrated into car management system, otherwise you risk all sorts of lesser installations!
As said ATC draws around 15A (recommended 20A fused supply), but the fridge can also draw 10-12A, so combined from a single supply that's likely an overload situation (both for any fuse fitted, but potentially for the cabling too!). Such is the heavy load placed on modern 13 pin towbar electrics, MULTIPLE earth returns are now employed to save overloading a single earth cable!
The way the fuse blows certainly implies that the ATC and fridge supplies are combined into a single source.
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Topic: Fuse tripping when I hook up for ATC +fri
via mobile 14/5/2025 at 8:58pm
