Question for the MOT examiners.

[apersson850]

Originally Posted by Laird Scooby

Ditto on the OBD-II, however i think they have a loophole (or should that be poophole?) whereby they can restrict access to certain areas and make them "Dealer only" as a generic spanner-monkey might not realise the implications of over-riding a particular setting.

This is true. The requirement is that the protocol concerning engine management and pollution related things should be common. Everybody should be able to check and repair these things. At the annual (or whatever) inspection, they should be able to plug in and read out if the car has found issues with emissions.
But for systems like air conditioning or infotainment, you can have your own communication protocol.

A good old 12N (Normal) and 12S (Supplementary) pair of towing sockets is much easier to fit, wire and diagnose if they ever go wrong which is less likely as there's less to go wrong!

This is just garbage. The 13-pole connector is much better than that stupid arrangement. If they forced the 13-pole on Britain, then lucky you!

We have only Volvo's own trailer module in our cars. Works perfectly. But there's no intelligence in trailers for cars. It's only for lorries that you also find intelligent nodes in the trailers, which implies the need to have compatibility between them.
For cars, it's just lamps and stuff in the trailer. The confusion there is sometimes that the trailer module senses the presence of the trailer by mesuring the current consumed by the position lamps. If they are all LED, it may be too low to be detected. Older Volvo TRM required 10 W to consider a trailer to be detected. It would then also turn on the other functions, like:

• Monitoring turn ligths, even when not in use.
• Monitoring brake lights, even when not in use.
• Turn off the rear parking sensors with a connected trailer.
• Adapt the image in the rear view camera.
• Remove the fog light from the car.
• Enable the cars anti-sway function.
• Turn on the switchable 12 V supply to the trailer.

[Laird Scooby]

Originally Posted by apersson850

This is just garbage. The 13-pole connector is much better than that stupid arrangement. If they forced the 13-pole on Britain, then lucky you!

But there's no intelligence in trailers for cars. It's only for lorries that you also find intelligent nodes in the trailers, which implies the need to have compatibility between them.
For cars, it's just lamps and stuff in the trailer. The confusion there is sometimes that the trailer module senses the presence of the trailer by mesuring the current consumed by the position lamps. If they are all LED, it may be too low to be detected.

All of this is garbage to use your words. The 13 pin connector is not as reliable for a start. Secondly, with the proper 7-pin system, if a fault develops in one system, that can be unplugged and you can still make it homoe - note that generally faults occurred with the Supplementary system for charging the trailers battery, running fridges etc meaning the lights were usually uneffected. Not possible to unplug half of the stupid 13-pin system!

However, your main point about no intelligence in trailers for cars. What controls those lights on the trailer? The CANBus system. Where is the CANBus system? In the car. The bulbs must still be CANBus compliant for the trailer electrics to work correctly, therefore the intelligence is there.

As for current detection, it's entirely possible to detect it at the level LEDs operate at, especially those used for bulbs as they need to be run at a high enough current to do their job. With most individual LEDs, current of less than 4mA means to all intents and purposes they're off as the light output is so low it wouldn't be seen, especially behind a lens unless it was truly dark - no sky glare from streetlamps, other cars headlamps etc.
Bear in mind the average If (forward current) for most LEDs is 20mA and for even a bulb equivalent in light output to a sidelight bulb (~100Lm) there would need to be a cluster of those LEDs. That means multiples of 20mA so easily detectible.

[Clan]

4.10. Trailer electrical socket,


You must only inspect the trailer electrical socket on vehicles fitted with a towing coupling.

If there’s no tow ball or pin, but the attachment brackets are still in place, you must assess the electrical sockets if the tow ball or pin has been:

detached
unbolted
otherwise removed
You do not need to assess the electrical sockets if the attachment brackets have been deliberately made unfit for further use.

You do not need to assess the trailer electrical socket if you need tools or specialist equipment to remove access panels in the bumper or bodywork to gain access to the socket.

A trailer electrical socket with a defective or missing cover flap that incorporates a lug and spring to hold the plug in place is not considered to be a defect.

13 pin Euro-socket
On vehicles fitted with a trailer 13 pin Euro-socket, use an approved device to check that the socket is wired to correctly operate the trailer:

position lamps
stop lamps
direction indicators
rear fog lamp
Some 13-pin test tools may continually flicker when plugged into the socket of a vehicle that uses controller area network bus (CANbus) systems.

Where this happens, it generally indicates that there’s continuity at each pin on the vehicle’s socket. When the lamps are operated in turn you will usually see that each individual LED will function correctly.

Provided the self-test facility on your tester does not show any faults, then you should pass the socket test.

Defect Category
(a) A trailer electrical socket:

(i) insecure
(ii) likely to become detached

Minor
Major
(b) Trailer electrical socket wiring:

(i) insulation damaged or deteriorated
(ii) insulation damaged or deteriorated and likely to cause a short-circuit

Minor
Major
(c) A 13-pin trailer socket:

(i) not functioning correctly
(ii) not functioning at all

Major
Dangerous

[37 RUBY]

Originally Posted by Ian21401

Trailer wiring now working as it should, apart from battery charging.

Ian

I had similar shenanigans on a Toyota we had fitted with a bespoke but non genuine wiring kit.

It ended with me running an extra cable from front to rear and incorporating a Voltage sensing split charge relay....something like this https://www.12voltplanet.co.uk/volta...-12v-140a.html

Just a thought...has the current system already got voltage sensing built in and the voltage sensed from the car battery is too low to allow it to split the charge current and is stopping it passing it to the caravan ?

A lot of the commercial 13pin kits don't actually cater for caravans and are basic wiring for a lightboard on a trailer or cycle rack...which don't need a battery charging.

I agree with your rant 're the 13 pin. It's failings aren't limited to poor connections or complicated wiring, the housing lock ring has a habit of locking in the wrong place stopping people from coupling up requiring jiggery pokery with a screwdriver if you don't have reset tool.The times I've had to bail out less technically minded caravanners as they try to leave the site but can't couple up.

[Ian21401]

37 Ruby,
One half of our combi split charge relay appears to be doing exactly what it should do, ie: only sending power to the fridge once the alternator voltage is sufficient. My gripe is that there is no dedicated pin for a feed to the battery, unlike the 12S system. If it were my car and I was intending to do some long trips to off grid locations I would try to utilise that second relay and pin 12, which at present are doing nothing. But that is academic as it isn’t my car and it’s not being used off grid.

[37 RUBY]

Ian

Pin 9 is the dedicated battery supply but pin 10 needs to also be live so that the caravans habitation relay is energised and allows the pin 9 voltage through.

So on your case if you're getting power to the fridge you should have power to battery. I would check the caravan wiring.