so i've been working on this install for like three weekends now and i finally got everything buttoned up yesterday. FTM-500DR in my 2019 tacoma, remote head mounted on the dash, main body under the seat. ran the power directly to the battery with an inline fuse, grounded to a bolt on the chassis near the seat rail.

everything works great except there's this weird buzzing/whining noise that kind of changes with the engine RPM. its not super loud but its definitely there, especially on VHF. UHF seems a little cleaner for some reason. antenna is a NMO mag mount on the roof for now until i get around to drilling, dual band 5/8 wave thing i had sitting around.

i know this is probably some kind of alternator whine but i wanted to ask before i start throwing ferrite chokes at it and making a mess. anybody dealt with this on a newer toyota? i've read some stuff about the ground being the usual culprit but i thought i grounded it pretty well. maybe the chassis ground near the seat isnt ideal?

yep thats alternator whine, classic. the RPM thing is the dead giveaway. first thing i'd try before anything else is running a dedicated ground wire all the way back to the battery negative instead of using the chassis. i know it sounds like overkill but newer trucks especially toyotas have all kinds of weird ground loops because of the electronics everywhere. the chassis ground on those is fine for a lot of things but for radio it can pick up noise from the ABS module, the ECU, all kinds of stuff.

also double check where your power wire runs — if it's anywhere near the factory wiring harness for any significant length that can also introduce noise. i had a similar deal in my tundra a few years back and just rerouting the power cable solved about 80% of it, then a small choke on the audio line got the rest. mag mount probably isnt helping either since the ground plane isnt great but that shouldnt cause the whine specifically.

the FTM-500 is a great radio btw, i went back and forth between that and the ID-5100 for months before i pulled the trigger. anyway yeah what the other guy said about the ground is spot on in my experience. also one thing people dont always think about — try moving the head unit cable away from your HVAC controls and any USB charging ports you have in the cab. i had some interference that turned out to be coming from one of those cheap USB adapters i had plugged in for my phone. pulled it out and like half the noise went away immediately.