Towbar Electrics

[lawser]

Looking for some advice on wiring up my towbar for a trailer....basically lights and indicators !

I have a 2003 C5 Estate, i have found behind the trim in the boot on the drivers side what looks like a factory fitted wiring harness coming from the light cluster, with a 7 multipin citroen connection, 5 wires white, 1 grey & one greenish in colour.

Can i fit my towbar connections to this or can anyone offer any help with colour codes or best side of the car to tackle the wiring from ?

Also do i need a bypass relay ?

 

Thanks,

 

lawser

[paul.h]

Copy of a note I posted last year after wiring up our hatchback (estate may be a bit different) - found by doing a search on towbar.

----------------------------------------------

 

I wired up a towbar on 04, 2.2 VTR this year.

 

The wiring kits will explain which wires go where, as KFK notes, use a 7-way bypass relay for the 12N socket and 12S socket reversing lights. Life will be easier if you use a Citroen kit.

 

At the back of the boot, under the plastic trim and carpet there is a trailer socket for the 12N lighting - I did not use this due to cost of Citroen parts and also the voltages were odd and not 12V. Instead I used the blue connectors to tie in to the lights to each car rear light and took these to the bypass relay and then the 12N and 12S sockets. I will add the lighting wire colours later.

 

I could not find any 12V supply in the boot with a high amp rating so the 12V positive supplies to the bypass and charging relays I took direct from the car battery clamp bolt, through a large wiring grommet into the car at the left passenger footwell (this was the difficult bit - first part pushed a welding rod through and fastened the cable to this and pulled it through with lots of WD40, removed windscreen plastic scuttle to improve access) and along the left side of the car into the boot - each wire needs to be at least 21 amp with 15 amp fuses at the battery end.

 

An earth point in the boot was used for the earth wires - again use 21 amp for the 12S socket.

 

Once wired up and checked, I stuck the relays to the back and side of the boot using sealant.

 

Rear light wiring colours:

 

left hand

- orange - left indicator *

- white/grey - fog

- white thick - stop

- yellow - left tail *

- white thin - reverse

 

right hand

- end grey - fog *

- blue - right indicator *

- white (next to grey) - right tail *

- white (next to blue) - stop *

- grey - reverse *

The ones with a * are the ones I connected to the 7 way relay with blue snap connectors.

[lawser]

Thanks, i'll have a look tomorrow !

 

lawser

[Phaeton]

The wires on my 52 plate 2.0l HDI were also numbered

 

290 Offside Indicator

289 Nearside Indicator

264 Offside Side Light

263 Nearside Side Light

2101 Brake Light on Nearside (I used this one)

2100 Brake Light on Offside

 

Didn't do Fog as I as never ever use them

 

Alan..

[PICASSOCONVERT]

Well, I thought I would take the easy route to fitting a towbar to my 03 2.2HDi estate. The Witter towbar went on easily enough today and I even manged to find my torque wrench to tighten the bolts to the correct torque.

 

So far as wiring goes, I thought I had that all sorted out too. I bought a Ctiroen wiring harness which a dealer was selling cheap and they checked my VIN to ensure that it would fit my car. However, the harness looks a bit fearsome - there are no fewer than 8 plugs.

 

As the dealer cannot supply any instructions, does anyone know if I will find 8 sockets to accept the harness when I remove the driver's side boot lining, or is able to point me n the direction of a wiring diagram?

 

Also, one plug has a grey wire and an orange wire which are cut from the equivalent wires in the harness as if something has to be connected "in-line". This plug also has a purple wire which runs into the harness and that part of the harness has an earth tag. does anyone know what this is for?

 

The final complication is that our new caravan is German and will have a 13 pin plug.

 

It looks as if I might be looking for a good auto electrician in the Luton/Bedford area.

 

All suggestions gratefully received!

[Guest digitalinkjetman]

Well, I thought I would take the easy route to fitting a towbar to my 03 2.2HDi estate. The Witter towbar went on easily enough today and I even manged to find my torque wrench to tighten the bolts to the correct torque.

 

So far as wiring goes, I thought I had that all sorted out too. I bought a Ctiroen wiring harness which a dealer was selling cheap and they checked my VIN to ensure that it would fit my car. However, the harness looks a bit fearsome - there are no fewer than 8 plugs.

 

As the dealer cannot supply any instructions, does anyone know if I will find 8 sockets to accept the harness when I remove the driver's side boot lining, or is able to point me n the direction of a wiring diagram?

 

Also, one plug has a grey wire and an orange wire which are cut from the equivalent wires in the harness as if something has to be connected "in-line". This plug also has a purple wire which runs into the harness and that part of the harness has an earth tag. does anyone know what this is for?

 

The final complication is that our new caravan is German and will have a 13 pin plug.

 

It looks as if I might be looking for a good auto electrician in the Luton/Bedford area.

 

All suggestions gratefully received!

 

You will need to ground the earth wire in this plug if you dont have the loop back to the ECU.

 

The ground works the bypass relays etc!

[Johndouglas]

I could not find any 12V supply in the boot with a high amp rating so the 12V positive supplies to the bypass and charging relays I took direct from the car battery clamp bolt, through a large wiring grommet into the car at the left passenger footwell (this was the difficult bit - first part pushed a welding rod through and fastened the cable to this and pulled it through with lots of WD40, removed windscreen plastic scuttle to improve access) and along the left side of the car into the boot - each wire needs to be at least 21 amp with 15 amp fuses at the battery end.

 

Nothing to add to what paul.h says other than the fact that if you use any power connection other than a 2.5mm square cable direct from the battery to your relays, you won't get satisfactory cooling at 12volts on a caravan fridge. Incidentally, I took the wire from the battery - suitably fused close to the battery, down the back of the engine, through the conduit covering the fuel lines, up over the fuel tank, through the access disc under the back seat and finally into the cargo area of the car. The two relays are housed in the right hand cubby box.

[PICASSOCONVERT]

Update - another day, the rain has stopped and the sun is shining, so on with the job. Progress so far:

 

Access to sides of load space achieved by removing the silver trim across the taligate by removing 4 screws, removing load space mat and floor (release 4 load eyes/locks and lift floor out). Remove boot lights, height adjustment switch and 12 volt socket from their positions and disconnect from harness. Gently remove side panels so that rear ends are free to flex into centre of car.

 

Surprise, surprise no sockets in the wiring harness (which is on the passenger side on my vehicle) to accept the towbar wiring loom, so off with the nearside light clusters. It appears that the towbar wiring might fit "in-line" with the existing harness - hence the large number of plugs and sockets.

 

Next step is to identify all the plugs and sockets - watch this space.

[PICASSOCONVERT]

Well, boot floor and side trim removed. Rear lights removed. I can see the principle of how it all goes together and the towbar harness fits into the existing harness OK but..................

 

The job needs someone who knows how the harness runs through the vehicle, so I am abandoning my DIY attempt and I'm off to find a professional to do the job for me.

[Guest digitalinkjetman]

Well, boot floor and side trim removed. Rear lights removed. I can see the principle of how it all goes together and the towbar harness fits into the existing harness OK but..................

 

The job needs someone who knows how the harness runs through the vehicle, so I am abandoning my DIY attempt and I'm off to find a professional to do the job for me.

 

 

If you want a hand Im not far away!

[PICASSOCONVERT]

Well, after a week away and time to think, I recommenced the towbar wiring job today.

 

This time the harness went in fairly smoothly - the Citroen part is designed to have the 2 relays in the compartment on the drivers side of the load area. From there the harness goes out under the car via a pre-existing hole. I just removed the existing rubber plug and fed the harness through. The harness has a matching grommet in the right place to re-fit into the hole. The connectors to each light cluster are designed to come up from underneath - I cut a small rectangular hole at each end of the black plastic sealing strip which runs across the forward end of the bumper (these holes are concealed by the bottom edge of the light clusters). The connectors on the harness fit into the loom in each light cluster and it is reasonably easy to get the wiring to sit neatly before replacing the lights. The harness was secured under the rear of the car using the cable ties supplied.

 

Although the harness was supplied for conncetion to 2 sockets, I have run the cables together in one conduit to connect to a continental-style 13 pin socket.

 

The next problem is to identify how the power supply works. There is a 3 pin connector plus an earth connection which appears to pick up the power for the relays and the fridge, but no matching connector in the vehicle wiring harness. I am guessing that this is wired as follows:

 

Orange wire (thick) - fridge +ve

Grey (thin) - trailer +ve

Purple - relay

Green/yellow - earthed to vehicle body

 

If I am correct, I can see that I could provide a high-capacity, fused +ve supply from the battery to provide the +ve supply.

 

However, I am not sure where the connection comes from for the purple wire and if it does actually operate the 25amp rated relay when the engine is running.

 

So any help on the above connections much appreciated.

 

Once I have the power supply connected up I can check the connections on the 13 pin socket and tidy everything up.

 

Once again thanks in advance for any help.

[Johndouglas]

I am guessing that this is wired as follows:

 

Orange wire (thick) - fridge +ve

Grey (thin) - trailer +ve

Purple - relay

Green/yellow - earthed to vehicle body

 

 

I can't follow your wiring colours. I have my C5 wired for a caravan giving road lights, caravan fridge at 12volts and caravan battery charging when the engine is running. It all runs off 12S and 12N.

 

I've taken two 2.5mmsqu wires from the battery to a twin fuse box, then down the back of the engine, into the conduit covering the fuel lines and down towards the back of the car. The wires then go up over the fuel tank and enter the car through the large access plug under the back seat. They then go into the load area of the estate hidden behind the panelling. A Smartcom and a Smart7 are fitted in the right-hand storage box. Wiring for rearlights, brake and indicators go to and from the Smart7.

 

Wiring the Smartcom has the fridge on red, battery on blue and earth on white. With the engine running the fridge is powered and the battery charges and the caravan 12volt system cuts out. When the engine stops and the car battery voltage falls to 13.2, fridge and charging stops and the caravan 12volt system switches on.

[PICASSOCONVERT]

Good morning John douglas and thank you for your comments, which are very helpful.

 

My next step is to reproduce your 2.5mm fused leads from the battery to the rear of the car. I feel reasonably confident that the orange and grey wires, for which I cannot find a matching socket in the vehicle harness, must be the +ve supplies for pin 9 (car +ve) and pin 10 (fridge +ve). Both these wires are cut in the Citroen towbar wiring harness which seems to suggest they are intended to be fused at the rear of the vehicle so I will add in-line fuses.

 

If the above is correct, it just leaves me to discover the purpose of the purple cable which looks as if it should attach to the vehicle harness. However it is possible that this is the power supply to the relay rated 25 amps (that and the other relay ought to provide the same functionality as your Smartcom and Smart7).

 

At the 13 pin socket of the harness I believe I have matched up all the wires except for a purple (which should - by process of elimination - be the equivalent of the more normal pink on pin 8 for reversing lights)

 

Tracing which wire leads to where in the harness should help the process.

 

I hope to at least get the road light operational by Thursday which is when I collect our caravan.

[Johndouglas]

I'm not familiar with 13 pin wiring but don't know if this helps:-

 

Connect to Socket terminal No.

Yellow See relay details 1 (LH Flasher)

Blue Fog Lamp 2

White Vehicle Earth 3

Green See relay details 4 (RH Flasher)

Brown R.H. Sidelamp 5

Red Stoplamps 6

Black L.H. Sidelamp 7

Yellow Reverse 8

Green Continuous power 9

Red Ign. switched power 10

Black Earth for pin 10 11

None 12

White Earth for pin 9 13

[PICASSOCONVERT]

Thanks again. Every little helps. There seems to be a fair bit of variation in wire colours for 13 pin systems - and more variations in the Citroen harness.

 

By the end of play today I had run 2 3mm square cables to the rear of the vehicle in the same way as you did and fitted fuses near to the battery.

 

I connected one of these wires to the orange wire in the harness and the other to the grey, having first checked that these wires fed through to the same colours at the 13 pin socket. I had also traced the earth wires.

 

I still cannot fathom the purpose of the purple wire which appears to be looking for a home in the car harness - I have fixed the socket end of this to pin 8 for the time being and taped off the car end.

 

Having put everything back toogether the lights on the car work as normal, which is a relief. Tomorrow I am going to pay a visit to the dealer so that I can hook the car up to the caravan and see what (if anything) lights up - this will give me a day to try and resolve any problems.

 

For information the wirng of the Citroen harness is currently as follows:

 

Pin 1 Yellow L/H indicator

Pin 2 Blue Rear fog lights

Pin 3 Green/yellow Earth pins 1-8

Pin 4 Green R/H indicator

Pin 5 Beige R/H tail light

Pin 6 Red Stop lights

Pin 7 Black L/H tail light

Pin 8 Purple Reversing lights

Pin 9 Orange +ve

Pin 10 Grey +ve fridge

Pin 11 Green/yellow Earth pin 10

Pin 12 Not used

Pin 13 Green/yellow Earth pin 9

 

This isn't too far from the scheme on the Sargent Electrical Services Ltd website.

 

I will report back tomorrow on what happens when I hook up to the 'van.

[paul.h]

This is only a guess without reading/thinking about your notes in detail, but is the purple wire meant to come from an ignition controlled +ve supply which is needed if the relay for the caravan supply is not the smart type that detect when the engine is running - otherwise the car battery will go flat.

[PICASSOCONVERT]

paul.h, thank you for your guess - it was spot on. Once I had connected the purple up everything worked fine.

 

The Citroen harness has 2 off 12V +ve supplies - orange and purple wires, and one switched one - grey wire. Unfortunately this wire isn't very thick and in due course I will run a 3mm square cable outside the harness to bypass it. I have already run a 3mm square cable for the fridge return.

 

Finally, thanks to everyone for their kind help.

[PICASSOCONVERT]

I will report back tomorrow on what happens when I hook up to the 'van.

 

Tomorrow has finally arrived - 6 months later! Sorry for delay in final chapter of story. Everything worked after one minor issue (indicators reversed). Next time - if there is a next time - I'll forget about a Citroen harness and fit an after-market one as others have done so successfully.

[paul.h]

No matter how long it takes, it is always good when a note is posted so we have the complete story and are not left in suspense.

[paul.h]

I have just finished fitting a towbar to a 2.2.hdi VTX estate 2007, replacement for our 2004 hatchback, wiring was different to our previous mark 1 hatchback, in particular the 12 volt supplies, hence the post.

 

The towbar was a TowTrust from Towbars Direct of Warrington, being only a few miles away, and the electrics a 7 way by pass relay for the lights and a smart relay for the caravan supplies. The 13 pin socket was wired with 12N and 12S cables which makes them easier to handle (so I was told) but can also be later fit to 12N and 12S sockets. I also got some other bits of wiring and connectors from Auto Electric Supplies (AES) through the internet at reasonable prices.

 

The towbar fit ok but refitting the plastic undertray for the bumper was a pain needing many goes to get the cutouts right for the ends of the towbar. It would have been easier if the car had been on a ramp.

 

To do the wiring, it was necessary to remove the boot plastic trim below and behind the left rear window (remove front screw and then pulls off, starting in the middle) and the side panel (pull up out of the top middle white clip) - both were left attached at the front. I also removed them from the right side but the side panel was not needed. The rear lights were removed to identify the colours and numbers of the wires as they go through the loom which gave:

 

Left light:

- brake - green - 2101

- tail light - blue - 263

- indicator - yellow - 289

- fog - purple - 201B

- reverse - white - 290 and 242

 

Right light:

- tail light - orange - 264 and 256

- indicator - orange - 290

- brake - brown - 2100 and 246 (not used for towbar but noted here)

- fog - white - 201A (not used)

- reverse - red - 224 (not used).

 

 

The car main wiring loom including the rear lighting runs from the dash fusebox down the left sill (plastic covers pull off), up over the left rear wheel arch, below the rear left window, splitting to the left rear light and up along the back of the roof to the right side and right light. I used blue snaplock connectors to tie in to all the lights wiring for the 7 way bypass relay below the left rear window.

 

The car has some wiring already for a towbar with the electrical connectors tucked out of the way next to the left rear wheel arch. The dash fusebox at the top yellow section has a direct battery supply, through maxi fuse 6 (80 amp) in the engine fusebox. The right section of this has fuses G36 to G40. G36 is for a 30 amp fuse through a beige thick wire B200 to the towbar connector - I cut off the connector and used this supply for the smart relay. Fuses G37-39 were in use but not G40 which would be a supply for electric heated seats so I pushed in a yellow 6.3mm spade connector to the top slot, connected with a wire (about 5 metres, 2.5 mm2 / 21 amp minimum needed) and fuse (15 amp) with spade connectors and along the sill route of the wiring loom to the back of the car to give a 12 volt supply for the 7 way bypass relay. There is an existing earth point at the back of the left window but the 12N/S cables did not reach so I provided another lower down. The 12N/S cables were connected to the bypass relay and smart relay and earth point following their instructions.