Koleos tow bar wiring

schlitzaugen

Member
1000+ Posts
So, now we're in the throes of wiring the tow bar and I was hoping there may be some connection point/plug installed at the factory.

There's a number of unused plugs hidden away behind the bumper, anyone knows what these would be for?

There's two small ones with four piddly wires on each side, just under the tail lights, I suspect these may be for parking sensors?

There's another one dangling off the bottom central plug for the bumper light, not sure what this could be for, only has two wires.

And the last one has six wires, and it is secured to the chassis just left of centre (above the exhaust tip). This one has been my greatest hope (six wires would be exactly what you need for signals, brakes, reverse and running lights) but none of the wires seem to be a ground so I am not sure what that plug is for.

Anyone can illuminate (ha!)?

I know I can hook into the tail lights themselves but I want to avoid that if there's wiring already provided. hanks in advance.
 

Haakon

Member
1000+ Posts
You're going to need a relay box - you cant just splice into the tail light feeds without totally freaking out the CANBUS system.
 

pugwash

Member
1000+ Posts
if its anything like a Peugeot 307 the wireing will be somewhere behind a panel on one side in the back, you may have to do some googling
 

schlitzaugen

Member
1000+ Posts
Thank you pugwash.

Renault is not very generous with the info, I have found a lot of instructions on fitting OEm tow bars, but they only show how to plug the supplied wiring into the existing harness, using a plug that I found on my car and it's in a very convenient location but that is carrying the multiplexed signal so without a decoder it's of no use to me. Which is only contributing to my determination to mickeymouse the hell out of this crap.

Effing computers. They're only making your life more miserable, I tells you.

I have the rear bumper off and I have figured out how to get to the wires directly at the lights. If I get really annoyed I will just splice some relays into these wires and be done with it. I found some nice small relays in my junk box (one of them) that draw only 30mA when closed and can carry over 10Amps, hopefully the lights computer is not that sensitive. These relays can carry over 10 Amps each and are small enough that I can hide them behind the bumper somewhere maybe in a water tight box if I feel generous enough so I figure I'm good. I figure if I find another connection point like you say, I still have to go through some body panel to get to the tow bar, which means drilling the car somewhere and between splicing wires and drilling the car I'll take the former any day.

I'll run a test tomorrow and see what happens. If splicing doesn't work, I have a plan B with some Reed relays controlling the power relays.
 
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REN TIN TIN

Member
1000+ Posts
Why don't you just buy a Canbus bypass relay, they're pretty cheap and do the job.
Okay, not as cheap as building it yourself from scrap relays.
 

pugwash

Member
1000+ Posts
there's a post somewhere about making your own for the 307 ,but may be easier to find the manufacturers box from a wrecker ,if you make your own you will still have to install a hot wire from the front or find one in the existing loom ,
 

schlitzaugen

Member
1000+ Posts
Yeap, that's the idea. No point in buying one, it's just a box of relays and you have to run a positive feed anyway for it. I have everything I need to make one right here.

I am not sure there's any wreckers here with Koleos in their stock and who knows what they would charge for it.
 

Haakon

Member
1000+ Posts
Yeap, that's the idea. No point in buying one, it's just a box of relays and you have to run a positive feed anyway for it. I have everything I need to make one right here.

I am not sure there's any wreckers here with Koleos in their stock and who knows what they would charge for it.

Bit neater and compact using the dedicated items, but youre right it isn't rocket surgery to wire up relays.
 

schlitzaugen

Member
1000+ Posts
Would the accessory socket in the rear cargo area be a good source of 12v+??
Yes, but you need to fuse the supply wire to the trailer lights, not sure what the socket can deliver (what fuse it has). 10A should be plenty I reckon. I am preparing a relay box with individual fuses for each relay to make life easier.
 

robmac

Member
1000+ Posts
I am preparing a relay box with individual fuses for each relay to make life easier.
You will discover that indicator (mechanical )relays will have a short life.

Is changed to solid state relays and eventually changed to mosfet transistors.
 

schlitzaugen

Member
1000+ Posts
I don't plan tow a lot so don't think it will be a problem. Even if the relays work when not towing anything, I still expect they will outlast our ownership of the car.

That said, the relays on my old cars rarely failed.
 

pugwash

Member
1000+ Posts
i presume it doesn't have reversing sensors .this is an issue we had with the peugeot as the original pug socket had a switch in the lid so when the trailer was plugged in, the sensors didn't continually go off as the car was sensing something too close ,led lights dont use much current so ,accessory socket could work ,easy to work out a loading ,brake lights parkers number plate and one indicator ,would be about the max ,i should imagine that most wreckers wouldn't be too keen to sell a relay separately as anyone fitting a bar would need one ,except the more creative ,
 

schlitzaugen

Member
1000+ Posts
Nah. No reversing sensors.

But today I had another idea.

Now when you use the flashers for instance, you can distinctly hear the click of the relay in the dash. So the lights are controlled by a relay. Which means that even if the relay is controlled by a computer, the lights themselves are still wired old skool. Which means you can still hack into the wires coming off the relay and add another light. I mean you don't need anything else. And yes, I know this may affect the flashing frequency. But it also means the factory setup does not need another "computer" to decode anything if you want to add wiring for a trailer's lights. Not sure why they can't be a bit more helpful and provide some info about it. It's not like it can't be figured out.
 

schlitzaugen

Member
1000+ Posts
Well, I have run some tests.

Tapping directly into the globes' wires (connecting another globe in parallel) works for some reason. No objection from the computer(s), no change in flasher frequency.

Using the accessory outlet (my car doesn't have one, but I have unearthed the plug where it was supposed to connect) will cut power when ignition is off.

The factory plug for trailer wiring is behind the left side boot panel, below the C pillar. A bit of a faff to get to, but it has all the wires, including the RH indicator. I am probably going to use this plug to control the relays, not sure about +12V, maybe I'll just go with the accessory wire and forget about it. Two handy grounding points inside the LH side panel, so should make the job easy.
 
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