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Discussion Starter · #1 ·
Hi guys,
I thought I would share a little project I did last week for my treg/trailer. I frequently tow a dual axle plant trailer (usually with building materials in it) and it has LED tail lights. My previous tow vehicle wasnt smart enough to have any problems with the LED trailer lights but it seems the touareg is, for whatever reason..... I note that the 7 pin plug on my treg is a NARVA plug (even though I have the factory towbar) so I cant speak to mine being wired differently than other of similar vintage, but suffice to say the treg would warn me of the trailer having all the bulbs failed.

Now since load resistors are kind of expensive if you buy them from a popular autoparts store, and not exactly neat either, I decided to rig up my own set of load resistors.

I bought 5 15ohm, 10W wire wound ceramic resistors at $1.80 each from a well known electronics retailer. I also bought a diecast box as you will see in the photo's, and a 7 pin trailer plug, and 7 pin trailer socket.

The idea is to make an "extension lead" with this box in the middle, containing the load resistors which are wired in parallel with all of the lighting circuits on the trailer. The service brake wire bypasses the box entirely. I would have run it through however miscalculated the size of the wiring glands which I fitted to the box, making for a less neat installation.

The crux of the installation is to allow the resistors to conduct heat away through the case, which is acting as a heat sink. To do this, I coated the side of the resistor mating up with the case with thermal paste (what you normally would use between CPU's and heatsinks, or for amplifier etc) and then used high quality epoxy to cement the resistors in place.

One side of all of the 5 resistors was then joined together to be joined to the earth return wire in the harness, and each of the lighting circuits joined to 1 of the resistors each. All the wires also pass "through" the box to the socket, where the existing trailer plug can be plugged in. Finally the enclosure is sealed shut with some gasket maker.

I did it this way for a couple of reasons:
1 - you only need to do this once, as if you have multiple trailers, you can move the plug box between them easily.
2 - the whole thing cost me about $40, whereas to buy 5 load resistors would have cost me about $100 and drawn double the current (most on the market seem to be 20W, which for the touareg at least, is not required).

Does it work? Yes, faultlessly for 600km over the weekend, and 100km of that over bone jarringly rough dirt road.

Anyway, I hope this helps someone!

A quick explanation of the resistors chosen:
Assuming a nominal 12V supply, the 15Ohm resistor will allow a current of 0.8A. The power dissipated by the resistor will therefore = V*A = 12*0.8 = 9.6W, thus making the 10W rated resistor sufficient (particularly when installed with a means to transfer heat away).
 

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MY21 Wolfsburg V6 Moonlight Blue
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Good stuff! Thanks for sharing
 

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Hi guys,
I thought I would share a little project I did last week for my treg/trailer. I frequently tow a dual axle plant trailer (usually with building materials in it) and it has LED tail lights. My previous tow vehicle wasnt smart enough to have any problems with the LED trailer lights but it seems the touareg is, for whatever reason..... I note that the 7 pin plug on my treg is a NARVA plug (even though I have the factory towbar) so I cant speak to mine being wired differently than other of similar vintage, but suffice to say the treg would warn me of the trailer having all the bulbs failed.

Now since load resistors are kind of expensive if you buy them from a popular autoparts store, and not exactly neat either, I decided to rig up my own set of load resistors.

I bought 5 15ohm, 10W wire wound ceramic resistors at $1.80 each from a well known electronics retailer. I also bought a diecast box as you will see in the photo's, and a 7 pin trailer plug, and 7 pin trailer socket.

The idea is to make an "extension lead" with this box in the middle, containing the load resistors which are wired in parallel with all of the lighting circuits on the trailer. The service brake wire bypasses the box entirely. I would have run it through however miscalculated the size of the wiring glands which I fitted to the box, making for a less neat installation.

The crux of the installation is to allow the resistors to conduct heat away through the case, which is acting as a heat sink. To do this, I coated the side of the resistor mating up with the case with thermal paste (what you normally would use between CPU's and heatsinks, or for amplifier etc) and then used high quality epoxy to cement the resistors in place.

One side of all of the 5 resistors was then joined together to be joined to the earth return wire in the harness, and each of the lighting circuits joined to 1 of the resistors each. All the wires also pass "through" the box to the socket, where the existing trailer plug can be plugged in. Finally the enclosure is sealed shut with some gasket maker.

I did it this way for a couple of reasons:
1 - you only need to do this once, as if you have multiple trailers, you can move the plug box between them easily.
2 - the whole thing cost me about $40, whereas to buy 5 load resistors would have cost me about $100 and drawn double the current (most on the market seem to be 20W, which for the touareg at least, is not required).

Does it work? Yes, faultlessly for 600km over the weekend, and 100km of that over bone jarringly rough dirt road.

Anyway, I hope this helps someone!

A quick explanation of the resistors chosen:
Assuming a nominal 12V supply, the 15Ohm resistor will allow a current of 0.8A. The power dissipated by the resistor will therefore = V*A = 12*0.8 = 9.6W, thus making the 10W rated resistor sufficient (particularly when installed with a means to transfer heat away).
That looks awesome,

I'm having the same issue.

Not having used thermal paste before, can you advise where I place it?

Does it set hard and do I set the resistors on top of it?

Thanks in advance.

Cheers
Kappy
 

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MY21 Wolfsburg V6 Moonlight Blue
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How about simply switching off load monitoring (on trailer lights)via vcds so you dont get the error?
 

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How about simply switching off load monitoring (on trailer lights)via vcds so you dont get the error?

If that is the case, I think that has solved a mystery that I have had since buying my Treg.

I have a boat trailer and a bike carrier bot of which have LED lights. The Treg came with a VW load box. It spends it life under the rear seat not connected to anything as I have no errors with the LEDs.


However, I do get errors when I hook up the bike carrier stop and tail light. The Treg reminds me to check the Left and Right trailer indicator bulbs.



The Treg has not figured out the difference between a trailer and a bike carrier.
 

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Discussion Starter · #7 ·
Some time on I can say this box is still working as it did when i made it. It lives out in the rain with the trailer too.
In addition, the car still tells me if theres something wrong with the lights aswell :)
 

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Hi guys,
I thought I would share a little project I did last week for my treg/trailer. I frequently tow a dual axle plant trailer (usually with building materials in it) and it has LED tail lights. My previous tow vehicle wasnt smart enough to have any problems with the LED trailer lights but it seems the touareg is, for whatever reason..... I note that the 7 pin plug on my treg is a NARVA plug (even though I have the factory towbar) so I cant speak to mine being wired differently than other of similar vintage, but suffice to say the treg would warn me of the trailer having all the bulbs failed.

Now since load resistors are kind of expensive if you buy them from a popular autoparts store, and not exactly neat either, I decided to rig up my own set of load resistors.

I bought 5 15ohm, 10W wire wound ceramic resistors at $1.80 each from a well known electronics retailer. I also bought a diecast box as you will see in the photo's, and a 7 pin trailer plug, and 7 pin trailer socket.

The idea is to make an "extension lead" with this box in the middle, containing the load resistors which are wired in parallel with all of the lighting circuits on the trailer. The service brake wire bypasses the box entirely. I would have run it through however miscalculated the size of the wiring glands which I fitted to the box, making for a less neat installation.

The crux of the installation is to allow the resistors to conduct heat away through the case, which is acting as a heat sink. To do this, I coated the side of the resistor mating up with the case with thermal paste (what you normally would use between CPU's and heatsinks, or for amplifier etc) and then used high quality epoxy to cement the resistors in place.

One side of all of the 5 resistors was then joined together to be joined to the earth return wire in the harness, and each of the lighting circuits joined to 1 of the resistors each. All the wires also pass "through" the box to the socket, where the existing trailer plug can be plugged in. Finally the enclosure is sealed shut with some gasket maker.

I did it this way for a couple of reasons:
1 - you only need to do this once, as if you have multiple trailers, you can move the plug box between them easily.
2 - the whole thing cost me about $40, whereas to buy 5 load resistors would have cost me about $100 and drawn double the current (most on the market seem to be 20W, which for the touareg at least, is not required).

Does it work? Yes, faultlessly for 600km over the weekend, and 100km of that over bone jarringly rough dirt road.

Anyway, I hope this helps someone!

A quick explanation of the resistors chosen:
Assuming a nominal 12V supply, the 15Ohm resistor will allow a current of 0.8A. The power dissipated by the resistor will therefore = V*A = 12*0.8 = 9.6W, thus making the 10W rated resistor sufficient (particularly when installed with a means to transfer heat away).
Just thinking, would it make sense to wire the resistor to the earth only - as it is common to all the lights. Has anyone tried it ?
 

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Hi guys,
I thought I would share a little project I did last week for my treg/trailer. I frequently tow a dual axle plant trailer (usually with building materials in it) and it has LED tail lights. My previous tow vehicle wasnt smart enough to have any problems with the LED trailer lights but it seems the touareg is, for whatever reason..... I note that the 7 pin plug on my treg is a NARVA plug (even though I have the factory towbar) so I cant speak to mine being wired differently than other of similar vintage, but suffice to say the treg would warn me of the trailer having all the bulbs failed.

Now since load resistors are kind of expensive if you buy them from a popular autoparts store, and not exactly neat either, I decided to rig up my own set of load resistors.

I bought 5 15ohm, 10W wire wound ceramic resistors at $1.80 each from a well known electronics retailer. I also bought a diecast box as you will see in the photo's, and a 7 pin trailer plug, and 7 pin trailer socket.

The idea is to make an "extension lead" with this box in the middle, containing the load resistors which are wired in parallel with all of the lighting circuits on the trailer. The service brake wire bypasses the box entirely. I would have run it through however miscalculated the size of the wiring glands which I fitted to the box, making for a less neat installation.

The crux of the installation is to allow the resistors to conduct heat away through the case, which is acting as a heat sink. To do this, I coated the side of the resistor mating up with the case with thermal paste (what you normally would use between CPU's and heatsinks, or for amplifier etc) and then used high quality epoxy to cement the resistors in place.

One side of all of the 5 resistors was then joined together to be joined to the earth return wire in the harness, and each of the lighting circuits joined to 1 of the resistors each. All the wires also pass "through" the box to the socket, where the existing trailer plug can be plugged in. Finally the enclosure is sealed shut with some gasket maker.

I did it this way for a couple of reasons:
1 - you only need to do this once, as if you have multiple trailers, you can move the plug box between them easily.
2 - the whole thing cost me about $40, whereas to buy 5 load resistors would have cost me about $100 and drawn double the current (most on the market seem to be 20W, which for the touareg at least, is not required).

Does it work? Yes, faultlessly for 600km over the weekend, and 100km of that over bone jarringly rough dirt road.

Anyway, I hope this helps someone!

A quick explanation of the resistors chosen:
Assuming a nominal 12V supply, the 15Ohm resistor will allow a current of 0.8A. The power dissipated by the resistor will therefore = V*A = 12*0.8 = 9.6W, thus making the 10W rated resistor sufficient (particularly when installed with a means to transfer heat away).
I just bought an adapter that plugs into the car and trailer for $30.00 from Amazon:
 

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Hi huskyguy.
Got underneath my van, found the wires from the flat plug, spliced the resistors into the line, and hey presto, all fixed.
Jayco's run the wires to a junction box underneath, so it was relatively easy to fit the resisitors, although I only fitted them to the 'Stop' and 'Tail" light circuit. I figure the Indicators are on-off, so no problem.
I didn't fit them on the car side because now anyone can use the van as long as they have a 12 pin flat plug.
Total cost, apart from my time which is nothing, about $5.00 for two resisitors.
If you wish to talk to me about it, give me a ring on 0408 320 410
Nobby.
 

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I just bought an adapter that plugs into the car and trailer for $30.00 from Amazon:
Some say the adapter may NOT solve the issue if having trailer with LED AND electrical brakes? Can someone confirm if it works?
 

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Some say that *** does not lie at every opportunity, but in this case the adapter will work with electric brakes as they have absolutely no effect on the LED lights and interact in no way.
If your problem is the module not "seeing" the LED lights on your trailer the adapter will take care of that problem and the signal for the brake controller will be generated if the module is set up correctly.
I tracked and traced no brake signal to the front connector that goes the the brake controller for a few days before the lights finally dawned.
If when the trailer is connected and the hatch still opens and the OPS does not show the trailer then it is not getting enough load on the light circuit going to the module and not acknowledging the trailer and generating no brake signal etc.
 

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i found that a single resistor on the tail light circuit tells the touareg that a trailer is present. It will then send the correct stop and turn signals to the trailer. It still warns that the stop and turn lights may have blown, even though they work correctly.
 
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