Simple Trailer/ Caravan LED light fix

**Briar** · 18th June 2016, 08:58 AM

Thought I'd share my solution here.

The new caravan has LED lights as do most new vans and trailers these days. I looked at various options for letting the Discovery know that a trailer is attached. I'm aware of plenty of aftermarket solutions.

The new van came standard with a 12 pin flat plug for most lights and brakesafe unit. I had thought about making adapters for the 12N and 12S sockets to the 12 pin flat, however, eventually decided to get auto electrician to wire in a 12 pin flat socket.

This left the 12N an 12S sockets effectively free.

I purchased a 12N plug, a bit of polypipe from Bunnings (about 31mm id), and 2 x 12v load resistors from an auto shop. Wired up the 2 load resisters to the 2 indicator pins and slotted them inside the polypipe. All wrapped up in tape to be waterproof. The 2 load resistors are back to back so when using indicator only each resistor acts as a heat sink for the other. Had to cut a small slot in polypipe to slide the 2 resistors in. Very snug. Works a treat. So effectively the LED resistor fix works in parallel with the new 12 pin flat socket. No annoying reversing sensor with van attached and definately lets D4 know a trailer is attached. Cost all up about $40-$50.

LED Fix1.jpg LED Fix2.jpg

**Graeme** · 18th June 2016, 11:06 AM

Also easy to unplug to avoid overheating the polypipe if you need to use the hazards for an extended period.

**scomac** · 18th June 2016, 12:28 PM

So if you left it in when not towing, would the D4 still think a trailer is attached?

**Disco-tastic** · 18th June 2016, 12:32 PM

Originally Posted by scomac

So if you left it in when not towing, would the D4 still think a trailer is attached?

Im guessing so.

I'm also guessing you could do the same with the white plug? And use the black for the trailer?

Is a nice solution!

Cheers

Dan

**LRD414** · 18th June 2016, 03:43 PM

Originally Posted by Disco-tastic

I'm also guessing you could do the same with the white plug? And use the black for the trailer?

Nope, indicators not in 12S white plug:

Cheers,
Scott

**Briar** · 18th June 2016, 04:34 PM

In Scott's picture above of 12N and 12S sockets the pin numbers are correct but you have to remember that in a D4 the 12N (Black) Socket on the right is rotated 90 degress clockwise so that Pin 1 is on the extreme right. Conversley the 12S socket is rotated 90 degrees Anti- Clockwise so that Pin 1 is on the extreme left.

Yes, if I left the Black Plug in that I made the D4 would still assume a trailer is connected as it would detect a resistive load on the indicator circuits which the D4 uses at startup and each time an indicator is used.

Haven't left it in by mistake yet.

I tested it out for heat output at first use. I left an indicator on for about 2 minutes and it was warm but not hot. Should be OK for up to 5 mins of continuous flashing on indicator or hazard. Much cheaper than getting something that is a pass through system mounted on the caravan which would only be useful on the van it would be installed on. I simply carry this plug thingy I made in the glovebox and I can use it on any van or trailer I tow that has LED lights.

**Disco-tastic** · 18th June 2016, 07:34 PM

Thanks Scott,

I had heard that the white plug was the UK tow plug, so assumed that it was similar functions in different order. Thanks for finding that pic!

Cheers

Dan

**LandyAndy** · 18th June 2016, 07:42 PM

If you were worried about it overheating one could use aluminium tube instead.
Its a great idea.
Andrew

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