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