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Discussion Starter #1
I have a 2014 TDI with factory towing. Dealer installed 7 pin receptacle in place of the blank that was supporting the harness. Everything works as it should with the exception of the 12v supply to the trailer battery.
I've searched and read any related posts I can find. Low or high trailer battery voltage makes no difference. My 2010 worked fine so experience with earlier years is not relevant.
One dealer took a quick look and couldn't resolve it in the time available but spent enough time to check connections and basic module data. They suspected a bad harness.
My local dealer has it now and he says the 2014 did not have this feature.
I have looked at the connector harness and there is a wire to the 12v location.
My questions?
Do 2014 Tregs with factory towing have the 12v supply?
Is there VAG module coding that controls this output?
 

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If you have a voltmeter, check this.


Note where the notch is and match up accordingly. If you don't have 12v back there, maybe you have a blown fuse?
 

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Discussion Starter #3
The trailer control module does not enable power to any of the terminals unless it detects a trailer connected. Only a very low sense voltage will be measured. It is very difficult to troubleshoot the system using standard methods and tools
 

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I've always been curious whether my Treg has been charging my trailer battery or not. Now I really wonder. The control module *does* make this hard to troubleshoot.

Do you know whether a trailer wiring tester (e.g. Towready TR20117 ~$15) presents enough load to cause the control model to think there's a trailer attached? If not I guess you could wire up a homemade tester for about $20.

I'm curious. How did you figure out that your 12v line was not working?
 

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Discussion Starter #5
i have an +/- 30 amp meter in the battery + line in the trailer. No matter what state of charge the trailer battery is in no charge is indicated with the vehicle connected and running. My 2010 would put 10-15 amps at idle into a 50% battery.
 

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Discussion Starter #7
The group leader in the service dept spent a lot of time with VW support on this and then with me personally. The wiring diagram shows a black B+ wire in the harness from the control module to the trailer connector and we confirmed it exists on my car. He reprogrammed the trailer control module to assure there was not a error there. I have not connected the trailer yet for results. This may be an issue only with my Treg. The service tech seems convinced we can get it working but he doesn't have a way of simulating a trailer connection either. I will follow up when I learn more.
 

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Discussion Starter #8
The 12v supply is working!
As described earlier, Wiring was confirmed and controller checked.....
Bottom line, after all this fiddling the 12v supply is there.
If you have a 2014 with factory towing package, there is 12v supply in the 7 pin connector.
I think a poor or intermittent connection from the harness to the Pollak 7 pin socket as discussed in deiseldom's post on OEM trailer harness may have been the root cause of the problem with my Treg.
 

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The 12v supply is working!
As described earlier, Wiring was confirmed and controller checked.....
Bottom line, after all this fiddling the 12v supply is there.
If you have a 2014 with factory towing package, there is 12v supply in the 7 pin connector.
I think a poor or intermittent connection from the harness to the Pollak 7 pin socket as discussed in deiseldom's post on OEM trailer harness may have been the root cause of the problem with my Treg.
Great to hear +12V is working! From your previous posts, have you confirmed Amperage at TT battery? Just curious cause somewhere, someone posted our Tow Modules must have some sort of sense circuitry that enables all pins when a valid trailer/camper is connected.

Dom
 

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Discussion Starter #10
Yup! confirmed it with the trailer amp meter. The trailer batteries were in a good state of charge so I saw only a few amps when I put a load on the system but I am confident it is working.
Yes there is sense circuitry. It is impossible to check any of the 7-pin outputs without a proper load on the circuit. There is even an adapter required if the trailer has LED lights because they don't present the expected load to the module.
 

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Again, thatz Great News! I read that the T3's had updated software or hardware that recognizes LED TT and Caravan lighting, negating the need for the special add-on devices used by previous generation Touaregs. Are you saying we still need this additional circuitry?
 

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Again, thatz Great News! I read that the T3's had updated software or hardware that recognizes LED TT and Caravan lighting, negating the need for the special add-on devices used by previous generation Touaregs. Are you saying we still need this additional circuitry?
Do not believe it. A plain old rental trailer with "normal" wiring and LED lights gave bulb out errors and intermittent indicator and stop light operation. I did not have the load box then - just drove it "as is". Although I think my problem was veeeery long lengths of cable from the socket to the trailer lights on the boat trailer. If I wiggled the connector at the car end things went crazy. Yeh I checked the connections - took the entire connector apart etc. I added a load box and no further issue. So I suspect that the load sensing is way off the mark still for LED lights.
 

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This must explain why I don't get signal or brake voltage at 7 pin plug on my 2014 Treg. It would be nice to test the plug before I drive the 7 miles to pick up my trailer. I didn't install a relay with my Prodigy P2 controller. Would this be a problem?
 

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Moodog, I just installed a BrakeBoss G2. With no relay. All checks out great for me:D
I will posts pix soon. I surmise the tow module senses a valid connection to activate. I 2 couldn't get a full confirmation of circuit continuity until plugging in to a valid TT. I purchased the Tekonsha 6562 loaded test plug thinking that may work, but didn't.
 

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Moodog, I just installed a BrakeBoss G2. With no relay. All checks out great for me:D I will posts pix soon. I surmise the tow module senses a valid connection to activate. I 2 couldn't get a full confirmation of circuit continuity until plugging in to a valid TT. I purchased the Tekonsha 6562 loaded test plug thinking that may work, but didn't.
That makes me feel a little better. This morning I ordered the plastic housing, VW part #1J0972782, and the 2 wires with the 4 slide in connectors, part#000979228E, for around $50.00. Probably a lot cheaper on Amazon. already connected my Prodigy P2 without the housing, but the connections are very close together.
 

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So have you picked up your trailer? Do you access to someone elses for verification prior to pickup? You may be all set and not even realize it!!
 

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2014 Touareg TDI trailer light connector location

I have a 2014 Touareg TDI R-Line. Getting ready to install a trailer hitch and lights. I can not seem to find the location of the plug or any source where a plug may be. Can someone help?
 
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