Towbar Information

[glenc]

Thanks Maverick

[Umai Naa!!]

The car conducts a bulb out test when the car is started and to do this it puts some juice through the bulbs. The electric brakes are seeing this as brake light activity and turning on the electric brakes. You should be able to get around this using a few diodes. Of course I could be wrong but I understand that electric brakes run off the brake light circuit?

Yes, and no. Depends how it's been wired up. I've been wiring them up off the brake pedal switch on the master cylinder, which is before any control module intervention. This seems to be the most effective method.

[Von Richthofen]

G'day Folks,

I'm not a passat owner but have just been through the trailer light issue with my '07 Jetta and thought my experience may be helpful.

I had just changed my boat trailer lights over to LED's. Connected the car & got the strobing issue. This is a result of the LED's being lower (see correction posted by tryingaVW below) resistance than the incandescent globes & the globe out detection system continually checking for resistance which would indicate that the globes were OK.

Negotiated a price with my local dealer for the VW LED Load simulator (Part No. VGA0055204 LOAD LED LOAD SIMULATOR 5A-300708RA) fitted the load simulator & all trailer lights working OK..... except for "LH trailer light out" warning via the MFD.

As indicated elsewhere in this thread the Australian standard for trailer wiring makes the tail lights common ie both lights fed from the RH tail light circuit form the car. Whereas the European standard is for an independent circuit for each tail light.

In earlier model VW's (including my '07 Jetta) there were only 2 options in the trailer light controller (North America & Rest of the World). VW have since developed additional codes for other countries, including Australia. The code for Australia basically stops the globe out detection system from looking for the LH trailer light circuit.

Even though the code for Australia does not appear on earlier model trailer light controllers the code (03) can still be entered into the system & it will work properly. This will solve the LH light out warning on the MFD.

My local dealer Wakeling fixed it for me in 15 mins while I waited & washed the car before giving it back to me...... No charge, as they treated it as a warranty issue.

Now for the LED load simulator..... I have pulled mine apart and checked out the components. It is made up of a number of 15W resistors that are wired in parallel with the trailers LED circuits. This effectively decreases (corrected 30/7) the load seen by the car without effecting the voltage across & current flow through the LED's

I have checked out the components & you would get change from $50.

I intend to make one up & permanently to mount on my trailer & will keep the VW model in the boot in case I get caught out & need to tow a trailer with LED's.

Regards, The Von.

[Swallowtail]

Thanks The Von... I found that exact same setting by fluke and resolved it myslef a long time ago. Good to know that is the correct way to fix it though! The local dealer had no ideas.

[Umai Naa!!]

Back in the early days when these issues were becoming apparent, VW said at that stage there was no support for LED trailer lights. They had then since released the load simulators, along with necessary coding alterations. This was all fine and dandy, and it worked well, but it was not widely known. Hence, why some dealers have been able to solve the problem (admittedly, Wakeling's have a gun VW foreman/technician there), and others haven't.

[tryingavw]

This is a result of the LED's being much lower resistance than the incandescent globes & the globe out detection system continually checking for resistance which would indicate that the globes were OK.
Regards, The Von.

minor correction : actually the LED lights have a higher resistance and do not draw enough current for the to see a correct load of approx 1Amp.

for the sake of completeness Von can you advise what resistance reading was marked on the resistors? i estimate it would be 1 Ohm. the Watt reading relates to the power the resistors can handle.

a normal trailer light is 15W ( and resistance of say 0.8 ohms) and would draw about 1 amp whereas the LED might be say 2W with a higher resistance of say 70 ohms and draw only 20 milliamps ( 0.02 A) .

[Von Richthofen]

Hmmm...... got me thinking now.

An individual LED if connected in forward polarity will present as a very low resistance (basically a switch) once the threshold voltage of 0.6 volts is reached. However, you are right, in a light array where the LED’s are connected in series there will be a resistor of some value also connected in series to limit the current flow through the LED’s. I’m not sure what the value of this resistor is in the case of the trailer light circuit. Also, the load simulator being connected in parallel is reducing the total resistance of the combined circuit that the car is seeing but I'm not sure to what value.

When I get the chance I’ll connect the trailer to a battery without the LED load simulator & measure the current so that I can calculate the resistive values of the individual circuits.

In the example you gave above of a 15w globe at 12 volts, the resistance of the globe will be 9.6 ohms & draw 1.25 Amps. Assuming my maths & memory of Ohm's law is correct.

In the mean time here are the resistance values in the LED load simulator.......remember these are connected in parallel with the individual trailer circuits:
Brake Light = 68 ohms
Turn Signals = 39 ohms each
Tail Lights (common circuit) = 2 x 33 ohms (in parallel) ie effectively 16.5 ohms

The actual resistors are Arcol brand, wire wound & the series is HS15 (the 15 designating 15 watts)

Once I measure the current in the LED circuits on my trailer, I’ll include the LED circuit resistances to the thread and determine exactly how much the load simulator is reducing the overall resistance of each circuit.

Regards....

[tryingavw]

you are correct, my maths was wrong. oooops.

FYI LED forward voltages are much higher than a diode- different colors vary- but about 2.5-3.5V when operating.

also the power rating can be worked out by v2/R. so brakes= 14*14/68 = 3W, so them using 15W resistors is very conservative, turn =5W . and the tail lights = 11.5Watts.

As it should always be with da Chermans. ( or the blockheads as i affectionately call them )

Best place to buy resistors is probably altronics online. Altronics - Your One Stop Audio Visual & Electronics Supplier.

Hmmm...... got me thinking now.

An individual LED if connected in forward polarity will present as a very low resistance (basically a switch) once the threshold voltage of 0.6 volts is reached. However, you are right, in a light array where the LED’s are connected in series there will be a resistor of some value also connected in series to limit the current flow through the LED’s. I’m not sure what the value of this resistor is in the case of the trailer light circuit. Also, the load simulator being connected in parallel is reducing the total resistance of the combined circuit that the car is seeing but I'm not sure to what value.

When I get the chance I’ll connect the trailer to a battery without the LED load simulator & measure the current so that I can calculate the resistive values of the individual circuits.

In the example you gave above of a 15w globe at 12 volts, the resistance of the globe will be 9.6 ohms & draw 1.25 Amps. Assuming my maths & memory of Ohm's law is correct.

In the mean time here are the resistance values in the LED load simulator.......remember these are connected in parallel with the individual trailer circuits:
Brake Light = 68 ohms
Turn Signals = 39 ohms each
Tail Lights (common circuit) = 2 x 33 ohms (in parallel) ie effectively 16.5 ohms

The actual resistors are Arcol brand, wire wound & the series is HS15 (the 15 designating 15 watts)

Once I measure the current in the LED circuits on my trailer, I’ll include the LED circuit resistances to the thread and determine exactly how much the load simulator is reducing the overall resistance of each circuit.

Regards....

[Von Richthofen]

Eventually got the chance to measure the voltage across & current flow through the LED trailer light circuits so that I could calculate the resistance value.

Circuit V, I (mA), Ω, Load Simulator Ω, Total Circuit Ω, I (mA)@ 12 v
LH Signal 12.9, 195, 66, 39, 24.5, 489
RH Signal 12.9, 193, 67, 39, 24.6, 487
Tail Lights 13.02, 46, 283, 16.5, 15.6, 770
Stop Lights 12.9, 197, 65, 68, 33.4, 360

Sorry about the formatting could cut & paste from excel successfully.

The LED load simulator is reducing the overall resistance by being inserted in parallel with LED trailer light circuits & therefore increasing the current flow through the combined circuit.

This reduced resistance & resultant increased current is obviously what is required to satisfy the VW can bus / globe test system and stop the trailer lights from strobing.

Regards, Von

[dammfool]

towbar

Does anyone know the size of the bolt that screws into the towbar to keep it tight

[Khun_tilt]

Interesting that you have a 13 pin Euro socket. I was just at a VW dealer today and they had two cars with towbars in the showroon - a sedan and a wagon. The sedan had a 7 pin roind Aussie socket nicely concealed I might add whilst the wagon had a 7 pin flat. N Euro. Maybe they have discontinued using the Euro plug as it in not Australian standard ( 5 (old), 7 or 12 pin are).

[Umai Naa!!]

On the recently-facelifted Passat, there is currently no wiring kit available due to some interference concerns with the Lane Assist system's radars.

[PASHN8]

How hard is it to retro fit a genuine VW tow pack to an R36 wagon? Anyone done it?

[Flipper Dog]

Along with the newly released Passat the Touareg has been having an issue with the tow bar, well just back from my dealer and ordered the bar in for fitting. It appears the "issue" is now fixed for both models but no one has told the dealers. My sales manager was as dark as midnight as he had two Touaregs and a Passat wagon he could have sold this week if he knew.

[scoutau]

Generally the VAG genuine kits come as 13 pin Euro and a 7 pin Aussie flat to 13 pin Euro adapter. Some Dealers have been fitting the adapter as permanent and cable tieing the 13 pin socket to adapter joint up under the rear apron because some of the locally sourced bars do not come with the drop down or permanent plate to mount the ISO1194 13-pin Euro connector. This happened to me and I am having it sorted as they just wrapped the joint in insulation tape which did not give a waterproof connection,they had even thrown away the rest of the 13 pin socket to compound matters!

There is also a problem with the VAG supplied 13-pin EU to 7-pin AU adapter in that pin 2 of the 13 pin EU (Rear Trailer Fog Light) has been wired to pin 5 (Electric Brakes) of the 7 pin AU socket! All because the same colour is used or a variation of on the Euro connector (Blue or grey/blue stripe IS1194.) and nobody thought to check it.

In as far as bulb fail goes for AU fitted lighting kits, check that the towbar has been coded properly by the dealer! In early systems only 2 options are given: EU and "Rest of the world" (0 and 1), now it is different and AU electrics on the towbar should be set to country code "3" as this allows park light only on right channel and left channel without bulb check I think. The system passes 1.7 volts DC down each lighting wire to detect a load and if no load is detected on 1 channel it shows that channel as bulb fail. Multiple loads ensure trailer detection to disable rear parking sensors etc. etc.

I am getting quite the expert with these problems with having to sort out my own with the dealer, VAG and towbar manufacturers! One other problem is VAG having incorrect labelling info on the "Genuine VAG" towbars themselves and the "Genuine VAG" Towbar manufacturers having no idea of the problem!

The towbar for an Octavia and Octavia Scout are the same, just with different mounting points between bar and frame. However the bar if fitted to an Octavia is only rated at 1300kg whereas if fitted to an Octavia Scout it is rated at 1600kg! The only label on the bar as per ADR states only the 1300kg for the 2wd liftback and wagon Octavia! VAG's response is "If anyone asks, show them the owners manual specs!", this does not work with Transport Inspectors or Police Traffic Officers in Australia and a fine occurs as well as having to leave the trailer on the side of the road and coming back in a vehicle with a bar at the correct rating for the load!

I paid for the correct rated bar when I ordered my car, I even made sure that the dealer understood the max rating and they verified with VAG accessory support and yet I still ended up with a bar with the wrong rating on it. I rang the NZ company who manufactures the towbars for VAG who knew nothing of the problems and now have placed the cat amongst the pigeons as VAG are legally culpable of a breach under ADR labelling specs as well as commercial mis-representaion maybe in regards to towbars option specs. Neither "Westfalia ag" or "Eric-Jaeger ag" make this mistake or have this problem in EU and they are the "Genuine VAG" factory option towbar suppliers to VW ag EU!

Sorry about that last bit, I will seperately post that in Octavia forum.
Cheers.