Trailer Control module on 2015 TDI Touareg

[jfalabella]

Hi there. I could use some help. I am getting a Trailer Control module "open fault" from the VAG. When I clear the codes, the error code comes back immediately. I don't know if this is from the control module itself or the wiring. The Receiver socket appears to be in good condition, as is the wiring to it. Looking for advice on how to narrow this down. I have tried several trailers, and none of them are lighting up.

 

[oilhammer]

I'd start with checking the connections to the module itself, and that it has power and ground.

 

[TurboABA]

Post the full scan that "the VAG" is giving you.

 

[jfalabella]

I finally extracted the controller from the car. So, I can put it back in and check for voltage and ground. The VAG code for Module 69 just indicated an "open fault" and there were no other codes that looked related. The one code came right back when cleared. Seems like there are a lot of these controllers out there for sale. Seems like I am not the only one who might have toasted the controller due to faulty wiring on my trailer. I could see that one of the 7-pin connectors (possibly RED AUX) got really hot and was corroded. Looks like some arcing might have happened at some point. I used to be able to fuss with the 7-pin connector and get the lights to come back on. But now... nothing at all is getting to the receiver connector. Is there a simple voltage check I can do at the connector to ascertain whether the controller is providing anything to the trailer when the trailer is not plugged in?

 

[TurboABA]

Codes come with FF data and all sorts of other useful information. You're not showing anything, so good luck with your diag.

 

[jfalabella]

Codes come with FF data and all sorts of other useful information. You're not showing anything, so good luck with your diag.

Here is the scan file. Please help me make sense of it. Thanks.

Log-WVGEP9BP1FD005253.txt

drive.google.com

 

[TurboABA]

Which part of the fault are you struggling with?
Have you checked the supply against the wiring diagram?

136203 - Supply Voltage 
          P1757 00 [009] - Open Circuit
          Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 3
                    Fault Frequency: 254
                    Reset counter: 137
                    Mileage: 101857 km
                    Date: 2021.02.12
                    Time: 14:23:04

 

[jfalabella]

Which part of the fault are you struggling with?
Have you checked the supply against the wiring diagram?

136203 - Supply Voltage
          P1757 00 [009] - Open Circuit
          Confirmed - Tested Since Memory Clear
             Freeze Frame:
                    Fault Status: 00000001
                    Fault Priority: 3
                    Fault Frequency: 254
                    Reset counter: 137
                    Mileage: 101857 km
                    Date: 2021.02.12
                    Time: 14:23:04

Can't get the trailer wiring to provide power to any trailer. Not sure how to validate whether it is the wiring itself or the trailer control module.

 

[TurboABA]

Did you read the second sentence of my reply above?

 

[jfalabella]

Did you read the second sentence of my reply above?

Did you read the second sentence of my reply above?

Well, I just found the fuse layout and am checking them first. Then I guess I would be looking for power getting to the receiver rcpt? I have checked for power there already and found none (with the car in "on" position and lights on as well).

 

[TurboABA]

No idea what you're saying, or looking at. I can only suspect it is "some alleged" layout, not the correct wiring diagram for your actual vehicle.
So, unless you have the correct wiring diagram, you'll probably go down the wrong path.....

 

[jfalabella]

No idea what you're saying, or looking at. I can only suspect it is "some alleged" layout, not the correct wiring diagram for your actual vehicle.
So, unless you have the correct wiring diagram, you'll probably go down the wrong path.....

I would love to get my hands on the correct wiring diagram. I can only google my car and find what is out there. What I am looking at has numerous fuses related to the trailer hitch. I am also looking at a post here.

 

[jfalabella]

I would love to get my hands on the correct wiring diagram. I can only google my car and find what is out there. What I am looking at has numerous fuses related to the trailer hitch. I am also looking at a post here.

Found the correct fuse layout and found one of the four fuses going to the trailer was blown. There are two 15 Amp and two 25 amp fuses. After clearing the codes and running the diags again, the "open circuit" is now gone. I plugged the trailer into the car and still no trailer lights. I need to test the car on a known good trailer.

 

[oilhammer]

Or go buy a simple trailer light tester to have on hand. Cheaper and easier than blowing fuses and possibly bricking an expensive module.

 

[jfalabella]

Or go buy a simple trailer light tester to have on hand. Cheaper and easier than blowing fuses and possibly bricking an expensive module.

Thanks. You don't know what you don't know..... so happy you pointed this out. Ordered one.