focus340
Member Since: 02 Dec 2010
Location: Hereford and Aldershot
Posts: 301
  
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| The final word in LED trailer wiring. |
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I've made the title of this thread sound a lot more dramatic than it prob will be but there are many many LED trailer wiring threads and I think there needs to be a final solution with close step by steps what to do.
I've just bought a 7 wire relay which is the quick fix however it doesn't give you the legally required trailer light flash on the dash when operating the indicators.
Jaws_172 seems to have the solution in a nice and tidy package
http://www.disco3.co.uk/forum/topic106532.html
I guess all we need now is a step by step guide of what is actually required to make what Jaws_172 has done. There's good pictures in the gallery but it doesn't really show you how to actually do it for the most basic of fettler.
If anyone else can knock together a good guide for this then feel free.
I'm sure this information isn't just valuable for me it'll be valuable for many people and it'll reduce the constant unknowns and questions that fire about on this matter.
Realise I'm asking a lot, but if you don't ask you don't get 
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 27th Feb 2014 12:33 pm |
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cmb6s
Member Since: 06 Sep 2013
Location: Herndon, VA
Posts: 73
  
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I’m actually somewhat confused by this device and wondering if somebody could explain it to my simple mind. Why is a relay necessary to include at all? I’ve only towed one trailer with LED lights so far, but the problem I had was that they flickered constantly when my headlights were off. Also, the truck did not recognize that anything was attached (i.e. the green trailer light on the dash did not light up when I put the turn signal on). However, the turn signals on the trailer worked just fine and the tail lights would function fine when my headlights were on. That tells me that the relay in the truck is working just fine for the turn signals and the only thing I need to do is tell the truck that there actually IS a trailer attached. I thought that the way to do this was to simply add a load that would mimic the load of an incandescent bulb. In other words, attach a resistor across each LED bulb. For the 7 pin connector, that would be a total of 4 resistors… each one attached in parallel across its LED bulb (1 for left signal/brake, 1 for right signal/brake, 1 for tail lights, and 1 for reverse lights).
Can somebody tell me what I’m missing? Thanks!
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| 27th Feb 2014 4:38 pm |
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focus340
Member Since: 02 Dec 2010
Location: Hereford and Aldershot
Posts: 301
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In all honesty I haven't even tried an LED fitted trailer to my Disco yet. I'm going to be rewiring my trailer to LED's but don't want to start until I've got the low down on the incompatibility and then can jig all the wiring up.
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| 27th Feb 2014 4:43 pm |
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cmb6s
Member Since: 06 Sep 2013
Location: Herndon, VA
Posts: 73
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Since the post was bumped, I thought I would answer my own question on here for those that want the info. As somebody else explained to me on another forum, the resistors are in the circuit in order to tell the Disco that there is a trailer hooked up (they simulate the presence of regular bulbs). The Disco sends out a continuous series of pulses to probe the wiring and see if there are lights (resistance) hooked up. Since LEDs don't provide enough resistance, we have to manually supply the resistance. However, this doesn't solve the problem of sending the pulses in the first place. These pulses are very low voltage and aren't enough to power a normal bulb. However, because LEDs require so little power, these pulses ARE enough to dimly light them. This is why they appear to be flashing. The resistors do not solve this pulsing problem. For this reason, the relays are added. They stop the pulse signals before they get to the lights. Hope that clears it up for others...
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| 17th Apr 2014 4:55 pm |
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Tufty
Member Since: 13 Jul 2010
Location: UK
Posts: 481
 
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cmb6s wrote:Since LEDs don't provide enough resistance
LEDs are very high resistance (compared to bulbs) hence the lower current.
Have a read through this thread as to why resistors and relays are required but basically the resistors are to 'fool' the disco into thinking there are extra bulbs plugged in and the relay is to stop the flashing due to the CAN bus pulsing.
http://www.disco3.co.uk/forum/topic101840.html
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| 17th Apr 2014 7:54 pm |
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