Aerial Issues but probably not the usual question

[Mr Mo-Fo]

Hi All,

I have been lurking on the forum for some time as it has a wealth of information but this is my first post in the hope that someone can give me an answer or has been there before and has the issue sorted out.

I have a 2007 adventura with factory (POS) satnav. I have tried to install a couple of aftermarket head units from Pioneer and Kenwood after sourcing the different dash parts I need.
The only issue I am having with all aftermarket units but not the factory unit is the radio reception, well to be precise the reception is fine - until I turn on either my sidelights or my factory HIDs.

I have tried several good grounds for the units/radio and the aerial is being powered OK so the aerial amp is not a problem and the reception is great apart from when the lights are on and then I just get a load of static.

Although I have factory HIDs and the ballast can interfere I still get the issue with just the sidelights on as well.

I have noticed that the factory aerial has 3 leads, pin, shield and power but the aftermarket conversion to normal din type just have 2 connections, pin and power but no outer ground ????

In theory I could run a 3rd cable from the outer part of the aerial to ground in the hope that this solves the issue but in all the posts I have read about installing an aftermarket headunit not one person has seemed to have mentioned this issue, it is normally just that they have forgotten to connect the power feed.

As said the factory unit is fine with the lights on it is just aftermarket units with the common item being the aerial convertor (I have tried 3 of these in case they where faulty).

Any ideas why I seem to be getting such interference which is giving me a major headache.

Many thanks in advance for any ideas / advice anyone can offer.