Tow Hitch Mk5

[Arch3r]

Can anyone recommend the best option for a tow hitch on my Mk5 in Perth?

I am a little shocked with the $800+ prices I have seen, as well as the ECU issues which were never a thing in the old days. Is there any possibility that a trailer with LED lights will not trigger any ECU hassles? I am happy enough to live with any braking compromise, considering I will only be towing a load of mulch around every now and then.

Happy to buy a used hitch if anyone has one.

[The_Hawk]

In the olden days the wiring would just sort of bodge into the tail light circuits.

Modern vehicles have a control box to manage the trailer lights. The systems with bulb out warnings rely on the load that an incandescent bulb puts on the circuit to tell you when one is blown. LED's draw so little power that these systems just think the bulb is out.

There are usually two options, turn off the warning completely or add in a resistor to add load to the circuit. In either case, you would never get a warning if you lose a bulb set.

Wreckers might be the go to pick up the needed parts, I'd just be careful on anything that has had rear-end damage.

[Arch3r]

I'm struggling to understand what purpose the extra ECU serves if I have LED lights. Does the car detect anything beyond current draw in the light circuits when the trailer is hooked up? And if not, then why do I need the extra box? What is it doing?

It seems a bit perverse to fit a tow-hitch requiring a separate ECU due to the extra load on the wiring, then have to defeat it due to not putting extra load on the wiring.. what am I missing?

I've found a used one complete with black box (not exactly cheap) but don't want to try fitting it and find I've angered the car's Black Box

[The_Hawk]

The extra box does allow it to detect the trailer being plugged in and disable parking sensors (and probably tweak other engine and stability/traction control things) so it does serve a purpose.

From memory you have to code the car to tell it you've added the module, otherwise it appears to be a mostly plug and play sort of affair.

I have heard reports of people hard wiring them in over the years, although I would be concerned about breaking some other expensive module in the process.

[Arch3r]

Fine, I give up then. I don't give a stuff about parking sensors (don't have them) or stability control. I know how to drive with a trailer. But hey, I'm sure my car knows better. I do read you can brick your ECU so it's just not worth the hassle. I'll probably buy a ****ty ute or something.

[Crafty]

Just got a Hayman Reese tow bar from Arrow tow bars in QLD, comes with the ECU, it's not actually an ECU though just an multi circuit electronic relay, it takes power from the fuse box and sends power to the trailer from there instead of using the cars light circuits, the cars light circuits are only used to switch the individual circuits in the relay - hope that makes sense.

[saabman]

I bought just the tow bar and built my own interface circuit - to optically isolate the the car from the trailer wiring - included self resetting over current protection as well - worked a treat. If you tap into the light wiring the tail light I seem to recall having to take the brake light signal from the boot mounted light rather than the tail light cluster - I think it was because the brake light and tail light were the one globe- it was a while ago and my memory is a bit foggy but I can look it up my notes if you want more info about going down that route.