I just installed some hid foglights and noticed thgey cause static to my fm radio, is there anything I can do to stop it?

 

I'm just throwing out life experience here so no guarantees...

This happened to me about 10 years ago on my car. Don't remember what it was that I was doing exactly electrically related, but I was installing something non-stock (either lights or audio equipment). Same problem.

First make sure everything is well grounded. I know, simple. Wasn't the problem for me.

The other thing that I was advised was to change my spark plug wires. Sorry but I don't remember from what to what. I THINK I changed to copper and it worked.

Just out of curiosity, does the pitch change with your RPM? That's what mine did.

Later, Formerking

 

No the pitch doesnt change,
Ill play out the senario for you,

So im driving down the highway at about 1am, im listening to my favorite country radio station (98.1fm).
I notice there is no one else on the road at this time and know there are alot of deer out so I flip the switch to turn on my hid fog lights, as soon as they kick on I loose my radio station (i hear nothing but white noise), turn them off and the station comes back on.

I wired up the lights with 14 gauge wire and have them turned on by a switch running to a relay with all soldiered and heat shrink tubing. The lights themselves and wiring are ran no where near any wiring for the radio.

Also I have upgraded all the ground wires under the hood (batt to frame, batt to motor, motor to cab, cab to frame, motor to frame, computer to cab) to 4 gauge wires with soldiered terminals. This is a main thing when installing a high end audio system also refered to as "the big three".

 

Also I have 8.5 msd wires with wire seperators keeping them from arcing

 

Should be able to get a noise filter from radio shack or allied electronics. Maybe a car audio place where you live. HID lighting is feeding noise into 12v circuit.

 

Since all HID lamps require a ballast, and the automotive types use high speed switching ballast systems, the HF energy is a likely suspect to the cause of your issues.

Exactly how and where the interference is coming from is a bit harder to diagnose without knowing more, but that is for you to figure out since you've got access to the truck.

It might be interesting to figure out if this interference only happens when listening to the radio or on any source. Since your radio antenna is grounded to the body, that could be one transmission source. Also, check AM as well; the different methods of broadcast and how that is affected or unaffected might provide useful clues.

The other would be at the power leads or any common grounds in the radio/stereo system itself.

The final problem could be related to the switching frequency of the ballast. No surprise the pitch doesn't change ... the power supply for the HV ballast could be at a fixed frequency, unlike the ignition system which changes with RPM.

I'm going to hope that isn't it, since it won't be that easy to solve. What worries me there is your saying that the station just cut out, and FM is frequency modulated, rather than there just being added noise to the channel.

HID lamp ballasts go through multiple stages. The first stage is first turn-on ... a high voltage source is required to cause the arc to cross the gap of the two electrodes. Once the lamps light, that stage is done, although it can repeat a few times since the arc lighting can be balky. Cold start will be about 2,000 Volts and hot re-start around 25,000 Volts or thereabouts, followed by a large current to keep it lit.

Second stage is filament heating. Once the lamp is in the arc discharge state, it needs a relatively long time to heat up. The second stage will continue to provide relatively large power to the lamp ... more than needed to keep it lit once warmed up.

Finally once operating at the correct temperature and in a steady state, the ballast can drop to the rated voltage and power, and monitor the state of the lamp as it ages, adjusting as necessary.

I wonder if you ran the lamps long enough to get to the steady state voltage stage. You could try an extended drive ... say 20 minutes ... with the HIDs lit and see if the problem changes or persists.

HID lamps are really arc lamps ... they were the first kind of electric lights in the world, first used more than 200 years ago, and existed more than 50 years before the incandescent light bulb. They are AC lamps ... not like your Halogens or an old style auto sealed beam or 1157, which don't care whether they're AC or DC, so they're DC in your vehicle.

So, HID's always operate at some frequency, and getting 25,000 volts from 12 means High Frequency Switching power supplies are necessary, and both have potential Electro-Magnetic Interference (EMI) issues. Your stereo is an AC frequency amplifier; your radio picks up AC waves, and so on.

All of this is a very long way to say be careful when you buy an aftermarket HID lamp system, because the operation, quality of shielding, quality and AC frequency of the HV switching power supply and frequency of the steady state powering of the arcs themselves, etc is not trivial and can easily lead to problems with the ECM or audio system. There is a reason why they first appeared in $70,000 luxury automobiles and why OEM parts are expensive.

It is probably a Very Bad Idea to buy the cheapest system on the shelf or from a company you're not familiar with. It is probably a much better idea to see if you can retrofit an OEM system to your vehicle.

You can get a transformer-based filter for the antenna; it will pass AC but block DC. It will also block AC above a certain frequency, and should block AC below a certain frequency (leaving the band your radio wants to hear free and clear) so if we're lucky the band pass will be different from what frequency the ballast operates at, filtering out any EMI from the ballast that your radio antenna is picking up. If the interference is coming via the antenna, that is.

Installing it won't harm your radio reception ... there's a decent chance it will improve it, HID or no HID ... so you may as well start there, and see what happens. Hopefully that will be that.

 

So the noise only happens when im listening to fm, I have not tried am, but there is no interference when listen to a cd!
So where can I find one of these "transformer based filters"

Also it doesnt happen to all the stations some come in clear!

 

A good RF filter can be found on numerous websites. The fact that the CD works indicates that your audio system is fine, and HID may be interfering with signal. RF filters typcially reduce or eliminate stray frequencies that override your radio reception. I am not sure that a RF filter will eliminate just the interference from HID, but they are inexpensive and will not hurt anything. I had to install one on a TV uears ago to keep a local radio station feed from coming across my TV.

And Johnny2Bad, excellent technical explanation. Gotta watch it if you and drewactual get together!

 

if it only happens on FM and only on some stations then I would think it's almost certainly an EMI issue with the ballast, probably related to the switching frequency of the High Voltage power supply.

By "some" do you mean just one, or more than one, and are they bunched up together or spaced through-out the band?

 

I actually just ordered some 4300k HID's for my projectors this morning....I put the 6,000k ones in my fathers f150 and even though he has the right housings for them I still get flashed every once in a while...I believe this wouldnt happen if they werent so blue and distracting...