DS5 Hybrid Tow Hitch / Tow Bar

[Ashleyn64]

Hi new to the forum,

I recently fitted a genuine Tow Hitch and wiring loom to my 2012 Citroen DS5 Hybrid.
Parts numbers:
Detachable Hitch : 9427 CS
Wiring Kit : 1606859980

I work in a Garage we fit Tow Hitches at least once a week. The lads in work fitted the Hitch and wired the Hitch but said it would have to go to a main Citroen dealer to be coded in.
So I went to the main dealer and was told after waiting 2 hours sorry we couldn't get the hitch to code in can you come back another day. I came back in the following week and waited another 2 hours. The car came out then they said it has successfully coded in when you get home test the trailer and if it doesn't work there is a wiring issue.
I have a bike rack which has regular bulbs and I have a small trailer which has LEDs. Both didn't work. I went back to work and got the lads to strip the wiring again and test everything all the wiring was 100%.
So I went to a different Citroen Dealer and they said Yes the hitch has been coded in they showed me Diagbox all the lights worked. When they sent the command from Diagbox all the lights worked perfect. The second they disconnected Diagbox nothing worked again.
I'm very confused the Main dealer said it's the wiring and the lads in work say it's a coding issue or a dodgy Relay Box that came with the wiring loom.

Any help or advice would be great appreciated. I have pictures and wiring diagrams if that help and a screen shot of the Diagbox detecting the trailer.

[GiveMeABreak]

All I can advise is that 1606859980 is the correct wiring kit, however, as you have a Hybrid vehicle with electric traction train, the wiring may need special attention, especially with the electrical system of the vehicle.

Diagbox is interfacing with the Control unit under the steering wheel, the BSI and Engine Fusebox directly and commanding the lights to work, but once you remove Diagbox, these systems are not getting the commands it seems - and that would indicate a communication / wiring issue. Diagbox can communicate directly with the ECUs I mentioned - but without it, something seems not to be getting through.

It's why with these electric Hybrid models, they specifically state in the instructions that the fitting must be undertaken by staff trained on these systems.

[Ashleyn64]

UPDATE:
Finally got to the end of the problem. The BSI unit wasn't tuned properly by the main dealer.

[GiveMeABreak]

The BSI configuration is part of the installation instructions for the official kits - I'd assumed that had been undertaken already, but glad you have found the issue and thanks for the update, it will help others with a similar issue.