AHK Coding

Hello community,

I'm new here and a complete beginner when it comes to automotive controls.

I have a Westfalia tow hitch installed on my VW T5 Transporter, including... Electrical kit (not pre-configured), then I purchased the VCDS kit and tried to code the trailer hitch.

According to the Westfalia instructions, I should select address word 19, "Diagnostic Interface for Data Bus," function 008 (service $22), and then select function 008.02. Well, where on earth is that thing? I can't find function 008.


I would really appreciate it if someone could help me with that.


You're welcome.

Hello Cello,

Forget the function numbers... here's the basic idea:
Okay, I'm ready. Please provide the German text you want me to translate.

You can also find similar posts and technical articles at the bottom of the page; the latter are displayed in black.

Best regards, Rainer.

Hello Rainer,

Thank you for your quick response. Yes, I have read this article, and I have also tried to code according to the instructions provided.

Steps for retrofitting a trailer hitch:
- In the CAN gateway, use the coding function to assign the address "19" and code the "trailer control unit." The VCDS coding assistant (tooltip or LCode) will guide you through the process.
- If a PDC (Parking Distance Control) system is installed (address 76), enter the extension length of the rear parking sensor in channel 2 by making an adjustment.
- If the parking assist system is installed (address 10), adjust the coding. The VCDS coding assistant (tooltip or LCode) will tell you how.
- ABS/ESP control unit (address 03), enable trailer stabilization if supported.
- Body control module (address 09), enable the function to switch off the rear fog lamp when a trailer is connected. The coding assistant (tooltip or...) VCDS's LCode feature tells you how.
- Engine control unit (address 01), reprogram to enable trailer hitch (standard or extended programming, depending on the control unit). Ignition ON, engine OFF. Unlike previous control units, no login code is required; instead, it uses encoding.
- If a reversing camera (address 6C) is installed, check and adjust its settings via coding as well.

However, at address 19, I can't find the "Trailer Coding" option because there's no corresponding setting or field.

"I see" the trailer control module in the parts list, and I've been able to code other control modules, but the connector is dark, meaning nothing is working there. Could this be due to a coding issue, or could something else be causing it?

Best regards, Cello.

Quote:

But with address 19, I can't "code a trailer" because there's no option or field where I could do that. I "see" the trailer control unit in the parts list, and I have been able to code other control units, but, and this is also a question I have, the connector is dark, so nothing is working there. Could this be due to the coding, or could something else be causing it?

The diagnostic gateway has a control unit address of 19. If you see the AHK control unit in the parts list, that's good; activate it by checking the box. Just like the other control units are activated there.

If you still don't have any power at the AHK socket, you need to check your wiring.

Also, please check the trailer control module using VCDS and look for any error codes stored there.

Best regards, Rainer.

Hello Rainer,

Thank you for your effort. I think I need to re-check all the cables again. The AHK control unit (address 69) is not reporting any errors, and none of the control units have previously reported any error messages.

Okay, let's get to work. Please double-check everything. I would be happy to share what I have found.

Best regards, Cello.

You're saying that the AHK outlet doesn't have power. How did you verify this?

The AHK control unit only activates the lighting outputs when it detects a trailer. In turn, it checks whether the trailer lights are drawing current by sending short voltage pulses.

If you simply connect a multimeter, you'll see: nothing. Therefore, simply try attaching a trailer or bike rack and see if there's really no other option.

Hello Guste100.

Thank you for your tip. Initially, I checked with the test plug (LED), but I suspected that the control unit (STG) was expecting a "real" load, so I connected a trailer. Unfortunately, no success either.
Last night, I was thinking about the relationships between the different control units (STGs). Is it correct that address 19 effectively only functions as a gateway and does not perform any control functions in addition to that? So, if I see STG 69 (trailer) in the parts list, does that mean it is also active? There are still no errors.


Best regards, Cello.

Cello_GR wrote:

Yesterday evening, I was thinking about the relationships between the various STGs, and is it correct that address 19 effectively only functions as a gateway and does not perform any additional control functions?

Sure, it only controls the data flows.

Cello_GR wrote:

So, if I see the STG 69 (trailer) in the parts list, does that mean it is also in operation?

What does "du sieht es" mean? Generally, all possible STG (Storage Tank Gauges) are displayed, but only those that are also marked with a checkmark are correctly supported.
Have you also activated the checkmark in the control unit and saved the new installation list in the 19er system?

Please check your car's diagnostic scan and post the results here.

Greetings.
Guste.