It’s the led lights.

I bet there is a PWM or some circuit in there somewhere on the led . The light bar perhaps.

I notice radio interference when my led back up lights engaged. Also had issue of severe interference with my first go round of H4 led bulb experiment.

Strangely though, the offending h4 bulbs produced no interference in friends van. So seems some radio installs more sensitive than others.

Alistair

> On Mar 16, 2018, at 9:40 AM, OlRivrRat <OlRivrRat@COMCAST.NET> wrote:
> 
>        Since the Brake Light Circuit is a simple On/Off Circuit I would doubt that it is the 
> 
> the Lights that are the cause ~
> 
>        My guess is that somehow the Brakes Themselves are Generating an RF Noise Signal ~
> 
> Hopefully 1 of our Resident Electronics Gurus will have the answer ~
> 
>                                                ORR ~ DeanB
> 
>> On 16 Mar , 2018, at 10:25 AM, Stuart MacMillan wrote:
>> 
>> Figure this one out:
>> 
>> 
>> 
>> When I depress the brake pedal I hear a faint high pitched "whine" from the
>> radio. It's pitch (frequency) changes with pedal pressure (higher with more
>> pressure), and only happens on AM stations. Unfortunately, my favorite
>> sports radio stations are AM so I hear it often.
>> 
>> 
>> 
>> It didn't change with a new radio last year, and I do have LED brake lights
>> and the GW high mounted LED brake light. Brake light switches have not been
>> replaced.  Whine was there with the 1.9 engine and is unchanged with my '93
>> Subaru 2.2 engine conversion. I have not switched the bulbs back yet, but
>> I'll give that a try and see if it goes away.
>> 
>> 
>> 
>> It's just a nuisance, but I'm stumped, particularly by the change in
>> frequency with pedal pressure. Any ideas why LED brake lights might cause
>> this? Maybe install a capacitor on the radio like this?
>> https://www.amazon.com/PAC-CSS12-Passive-Filter-Capacitor/dp/B000CEDZBA
>> 
>> 
>> 
>> Stuart
>> 
>> '85 Westy