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Tow bar electrics

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Tue Sep 22 2015, 05:32am
Member No: #41974
Joined: Sep 08 2015
Location: teesside
Have been told I will need a CANbus? for the tow bar electrics, what is it and is there any place to purchase through the site, or would it be better to get a full specific wiring kit?
Tue Sep 22 2015, 05:40am
Member No: #574
Joined: Jul 08 2007
Location: Dorset
CANBUS is the electrical system that operates all of the electrics on these cars. Cutting into the electrics on these cars can upset the Canbus system and lead to all sorts of issues. It may be worth taking it to a specialist fitter or a Citroen agent.

If you see Canbus in red on a post, click on it and it will lead to many threads on the subject.
1 User said Thank You to routemaster1 for this Post :
 pickledmagpie (22 Sep 2015 : 07:08)
Tue Sep 22 2015, 05:49am
Member No: #41974
Joined: Sep 08 2015
Location: teesside
Also could anyone tell me if this item will do the job 181654908702 its the e bay listing number
Cheers dave
Mon Sep 28 2015, 02:16pm
Member No: #5234
Joined: Sep 04 2008
Location: Lincolnshire
I have just read the spec for the eBay item you have mentioned. I reckon that this only a canbus bypass relay system. I believe these are really only suitable if you only intend towing a lightweight trailer or to power a lighting board for a bike carrier. you can certainly find cheaper on eBay e.g - Click Here -

I believe that if you intend towing a caravan or anything heavy you would be better advised to go the whole hog for a genuine citroen tower wiring kit. This then has to be programmed in/activated by your dealer.

This sort of kit does not just sort out the lights but tells the onboard computer that a trailer is connected, disabling the reversing sensors but far more importantly modifies the ABS and other braking parameters
Wed Jan 27 2016, 09:32am
Member No: #11625
Joined: Nov 30 2009
Location: aberdeen
Hi pickledmagpie, it's a total myth that the ABS/ ESP function is modified when you tow with Canbus electrics connected (at least on any Citroen).

Mon Aug 08 2016, 10:57pm
Member No: #38558
Joined: Dec 24 2014
Location: Kerry, Wales
I have been towing my caravan for 2 years with just a Bypass kit and split charge relay and I have never had a problem.

I would never pay the money for dedicated electrics when the job can be done for less than £30 yourself.

It was quite straight forward to do, I have LED real lights on mine and I still fould the power for the lights easily.
Tue Aug 09 2016, 01:56am

Member No: #82
Joined: Jan 22 2007
Location: Hoylake
The dedicated Citroen kit is pretty sophisticated and maintains/adapts all the systems when a trailer is present, including such things as disabling reversing sensors when a trailer is attached and detecting failed lights.

Bypass systems need to be fitted carefully and correctly to avoid interfering with the CANBus. There is a warning attached to the wiring of the car indicating that no more than an extra 10mA (i.e. next to nothing) should be drawn from the wiring.

AFAIK the C4's ABS is sufficiently advanced to automatically compensate for the presence of a trailer. It does not require modifying/upgrading for trailing towing.
Tue Aug 09 2016, 04:10am

Member No: #19238
Joined: Apr 12 2011
Location: Cambridgeshire
Eye, the ABS/ ESP system take account of the car empty and loaded too - the car works it all out itself.
Sun Jan 29 2017, 05:16am
Member No: #28625
Joined: Dec 21 2012
Location: Bedfordshire
Hi all,
That was good reading but a bit disturbing for a non electrician.
I have just replaced an 09 VTR+ with an 15 Exclusive and want to have a tow bar fitted for the occasional use of a small trailer.

I have had a couple of quotes £296 & £350 and the second one mentioned the stability program.
I then looked on this section and it seems that there is potentially a lot more to it than I thought ( Canbus etc.).
What should I ask these fitters?
Does anyone know what a Citroen dealer would charge for the Kit.
What changes to the computer are necessary.
Many thanks for your info above and for any suggestions you give.
Sun Jan 29 2017, 07:15am

Member No: #19238
Joined: Apr 12 2011
Location: Cambridgeshire
The by-pass kit works fine - there are lots of horror stories out there about not using 'Citroën' official kits but my advice is use a local reputable fitter and you'll be fine - ours is a demountable 13-pin set and it cost £440; the reason I chose this route is that most of the Citroën dealers we spoke to confirmed they used local fitters to do their work as 'Citroën ones are too expensive'. We've had no issues so far.

The official kit does not recalibrate the ESP etc., the car does this all automatically based on how it is loaded.

Citroën wanted £1,026 to fit a demountable towbar...
Sun Jan 29 2017, 07:49am
Member No: #42824
Joined: Nov 29 2015
Location: Cardiff
I chose not to have the factory fitted towbar & electrics option as it was an extra £1000 and opted to have an after market one fitted by Indespension.

A Westfalia detachable towbar and dedicated 13 pin electrics, cost around £600 ish.

Everything works OK, so I'm happy and it tows my Orion 440/4 nicely.

I did find out later, that the electrics kit from Citroen was cheaper than from Indespension by about £10, (I'm told they are from the same manufacturer) but still cheaper than the factory fitted option.
Mon May 08 2017, 11:41am
Member No: #47318
Joined: Jan 18 2017
Location: hampshire
Just in the process of fitting tow bar and electrics to my 2013 C4 Picasso. Take my advice, buy Citroen genuine parts especially the wiring kit.

I have just paid £98+VAT for a genuine dedicated kit from a Citroen main dealer. Alternative non Citroen (by-pass?) kit to do the same job was £192 inc VAT. Genuine tow bar manufactured by Thule was about the same price as a good quality tow bar.

Fixed swan neck does not appear to interfere with parking sensors. Tow bar fitted easily, picks up on mounting points that are factory fitted and can be fitted by taking out wheel arch liners on both sides and dropping lower bumper 5 screws. Squeezing the main bar into place a 2 man job really. The down side if you are doing it yourself is how the hell do you get the side panel in the boot off! The major control box and wiring all fit in this area. There is no Haynes manual for the post 2013 Picasso and no information that I can find on the internet. This and the door kick plates have to be removed before fitting wiring loom.

Can anyone help?

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