RF Speaker Noise (1 Viewer)

[open country]

Hey all, have been searching at length on this topic but haven't found this specific issue (if I missed it and someone has a thread link, please let me know).

My 83 has speaker noise/interference/whine from the passenger front only when the engine is running. It has an older aftermarket head unit, speakers, and 4-channel amp setup, which definitely introduces some variables, but I've run the truck with no audio source and both head unit and amp unplugged and the noise persists which leads me to something under the hood. The noise fluctuates with throttle input while driving (quieter when engine is under load, louder when idling).

I'm not skilled with electrical diagnosis so appreciate the help pointing me in the right direction.

Video below - the fluctuations in the speaker noise are from me pressing the throttle pedal with head unit and amp power sources disconnected.

 

[84Landie]

Check your grounds on the head unit. Does it change with engine rpm? I've had to ground the body of the head unit before due to electrical interference.

 

[OSS]

This is an age old car stereo issue - and there’s a fix.

Do an internet search for “car radio noise suppresion”.
There lots of info (and big capacitors you can install if needed)

 

[lcolon]

You can also try adding a ferrite bead to the power leads to the radio and maybe on the speaker wire. Something like this: Ferrite Ring Core Black RFI EMI Noise Suppressor Cable Clip-20Pcs

I would get them up as close to the radio and/or speaker as possible. They act as an RF choke.

 

[open country]

Check your grounds on the head unit. Does it change with engine rpm? I've had to ground the body of the head unit before due to electrical interference.

It does, but most noticeably with engine load. Crusing in 4th I can manipulate the noise with the throttle pedal even though RPM isn't changing.

Would the head unit ground matter though if the head unit is out of the truck? Noise is there with head unit off and with it completely disconnected sitting in the seat next to me.

This is an age old car stereo issue - and there’s a fix.

Do an internet search for “car radio noise suppresion”.
There lots of info (and big capacitors you can install if needed)

Thanks, have been lost in Google searches with infinite vehicle types, setup variables, and solution recommendations so thought I'd check if this is common to FJ60 and if anyone has fixed.

You can also try adding a ferrite bead to the power leads to the radio and maybe on the speaker wire. Something like this: Ferrite Ring Core Black RFI EMI Noise Suppressor Cable Clip-20Pcs

I would get them up as close to the radio and/or speaker as possible. They act as an RF choke.

Will give these a shot, thanks.

 

[open country]

Humbling update - after removing the speaker itself and still hearing the noise, realized it's from the VCV vacuum diaphragm on the firewall. PO had removed the VCV during a desmog and routed vacuum from distributor cap straight to cabin.

Thanks for the responses, haha.

 

[TexasLandCruiser]

Humbling update - after removing the speaker itself and still hearing the noise, realized it's from the VCV vacuum diaphragm on the firewall. PO had removed the VCV during a desmog and routed vacuum from distributor cap straight to cabin.

Thanks for the responses, haha.

Well at least you don’t have to chase a bunch of wiring now! Good news