Evening all,

Apologies in advance if this has been discussed before I did search and couldn't find what I was looking for.

So I want to fit a towbar and I'm curious about the electrics/wiring, you can buy a trailer control module for this but I don't want to pay £150 for the privilege, I had the idea of making an inline twin plug loom so it will be plug and play, but is there a reason this isn't done factory? Will it cause canbus errors 🤔, any info greatly received

Edited 19 March, 20251 yr by matt_j

Doing what you suggest will definitely cause Canbus errors - failed light warnings, etc. You need the correct wiring kit.

7 minutes ago, Warrior193 said:

Doing what you suggest will definitely cause Canbus errors - failed light warnings, etc. You need the correct wiring kit.

Flashing, fail lights it is them 🤣🤣

I’m considering the same at the moment.

The last time I fitted dedicated electrics was on a Passat, about 10 years ago. There were lots of wires to add to the fuse box and an ECU plug, IIRC.

I was more flexible back then, my eyesight was better and the fuse box was more accessible than the Octavia.

According to PF Jones’ website, a bypass relay can be used. I might go down that route.

Here's the bypass relay...

Towbar Universal Electrics Bypass Relay

On 19/03/2025 at 21:15, matt_j said:

I had the idea of making an inline twin plug loom so it will be plug and play,

Can you explain what you mean by that please?

On 19/03/2025 at 21:38, daveo138 said:

According to PF Jones’ website, a bypass relay can be used. I might go down that route.

They work just fine, no bulb errors.

The only thing to be aware of is that they increase the standby power consumption as they are not ignition switched (so as to work with parking lights) which will reduce the standby autonomy of the battery, modern ones take far less current than the old school ones but its not negligible.

On 19/03/2025 at 21:21, Warrior193 said:

Doing what you suggest will definitely cause Canbus errors - failed light warnings, etc. You need the correct wiring kit.

I dont understand what he is suggesting.

Hi all,

Hope you’re well and can help please!

I have one of the relay bypass kits and also the wiring diagrams for the Octavia 3. I’ve checked the diagram for the left side and there are 2 black and white wires shown but on the can I have 2 black and white wires but one has red dashes as well.

Does anyone know which is which please? It doesn’t differentiate on the drawings.

Also this is in addition to the white and black wire!