radio interference when lights switched on.

ibizaneal · Oct 22, 2015

Hi everyone, this is my first post so please be gentle. I have a 2003 defender TD5 90 CSW.

I recently fitted an LED light bar to the existing spot light loom (old spots replaced with bar) but have found that when it is switched on I get interference through my radio. It doesn't do it when i have my Ipod on though and didn't do it with the old spot lights. Does anyone have any ideas as to what might be causing this and possible solution.

Thanks in advance. Neal.

mick the builder · Oct 22, 2015

Back in the dark ages we used to fit a suppressor on the live feed or a suppressed in line fuse.

ibizaneal · Oct 22, 2015

would the old spot lights not have needed a suppressor then?

mick the builder · Oct 22, 2015

No, afaik. Spots are just switched on via a relay and get a constant supply. Not sure how Leds work.

ibizaneal · Oct 22, 2015

That's how they are wired up, through the existing relay for the old spot lights. The only thing I can think of is electromagnetic interference if the cables are too close to the aerial.

mick the builder · Oct 22, 2015

send cowasaki a pm.

Flossie · Oct 22, 2015

Cut through the alternator drive belt with a sharp knife ( stop injun whilst doing this)
Taadaa!

zeaphod · Oct 23, 2015

Some LED lights can cause RFI interference. I have experienced this on my bike, where a particular light interfered with the wireless speedo enough to stop it working. Might be worth speaking to the supplier, or if that's not an option, try temporarily wiring the lights with a flying lead, and move it around to find a routing that is further away from the aerial.

ibizaneal · Oct 23, 2015

That was my thought, I was going to use some plastic flexi conduit to put the aerial through to try and see if that worked.

discomania · Oct 23, 2015

ibizaneal said:
That's how they are wired up, through the existing relay for the old spot lights. The only thing I can think of is electromagnetic interference if the cables are too close to the aerial.

It will be the LED drivers. The LED's themselves won't just run directly from the 12V supply like a incandescent lamp did, as they need to have the current controlled. Not quite sure what sort of lights you have but they probably have a little constant current driver to run the LED's within electrical spec, clearly with no electromagnetic interference (EMI) suppression. This will cause interference on the electrical system (but the radio probably has it's power feed filtered) or more likely radio interference which is then picked up on the radio and amplified due to the fact it is not getting to the amplification circuits when only running the IPOD.

Try fitting a ferrite choke, one at the beginning of the feed to the lights and one up before the supply enters the lights that will help to eliminate radio frequency interference (RFI) being emitted or use a screened cable. Keeping the live and neutral close or even twisted will help too.

discomania · Oct 23, 2015

ibizaneal said:
That was my thought, I was going to use some plastic flexi conduit to put the aerial through to try and see if that worked.

Don't waste your time on that, radio waves go through plastic! Clean up the source of the EMI.

ibizaneal · Oct 23, 2015

Thanks everyone, ill try the ferrite chokes and see if that cures it.

gazman · Oct 23, 2015

I have exactly the same problem. I don't have led headlights but led everything else. I only get it when on high beam. Do I need to do the same?

discomania · Oct 26, 2015

gazman said:
I have exactly the same problem. I don't have led headlights but led everything else. I only get it when on high beam. Do I need to do the same?

So when you say you don't have LED headlights, then your dip & high are both still halogen? If they are still halogen yet cause radio interference it sounds more like alternator noise under load or a bad connection on the high beam circuit somewhere causing some EMI. If you load the system up with everything else except the high beams, does it still make the noise, if so alternator phase whine on high load.

gazman · Oct 26, 2015

I can have everything on and get no interference, but when I use the main beam I get it.
The side lights, brake lights, fog, drl and indicators are all LED. The main/dipped are normal halogen

discomania · Oct 28, 2015

gazman said:
I can have everything on and get no interference, but when I use the main beam I get it.
The side lights, brake lights, fog, drl and indicators are all LED. The main/dipped are normal halogen

Sounds like a connection issue/bad ground.

I've rebuilt my 90 from the chassis up, rewired it with custom looms and wiring but I actually don't know if they have a high beam relay or not, they should! Don't have my 90 with me just now so can't go and look.

So...I would rule out an EMI inducing relay coil first by pulling the plugs off your headlights and switching to main-beam with them physically disconnected. If the noise still persists then it could be a the coil (magnetic) on the relay.

If the noise disappears then plug 1 headlight back on and activate high beam... if it comes back then pull the plug again and try plugging in the other side. You might be lucky and find it is a sided issue, which will let you then work on the connections at that side. My first bet once you found a side would be the earth connections on the inner wing.

Good luck!

gazman · Oct 28, 2015

Thanks I will look. Turns out after changing the fuse in the drl's i do get interferance from the and they are LED

radio interference when lights switched on.

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