buzzing from inside cab passenger side

[86 720]

Started the truck and buzzing came from passenger side right above the speaker. I'm thinking this is the fuel pump relay?
My battery light came on and the buzzing stopped at higher RPMs.

[ADDirishboy]

I won't be of much help on this one. Let me go find Pezi and see if he can't help you out with this one though.

[PEZi]

my truck did this a few times as i chewed through alternators.... that's why the battery light comes on... keep an eye on it but you may need a new alt

[86 720]

Stopped at NAPA, they were to cross reference the rela, but it still buzzed when I put the new one in however not as much. It now stops buzzing at a lower RPM than before. From what I remember from the manual, there are two relays right above the right speaker, roughly the same shape and size as a 30A relay. The one that is buzzing is the one on the right. My truck only has 1 relay in that location, but I remember the manual showing two relays.

I also noticed my batt light illuminated with the RPMs of the engine too. Methinks my alternator needs replacement too.

[PEZi]

the reason for the buzzing is not enough charge from the alt to the batt... you get more charge flowing at higher RPM thus no buzzing

[86 720]

Yep! Took the alternator to Autozone after work and it failed their test. Since it was still under warranty, I got a new one, now it's all better!

[MetalFab]

humm.. drove my rig over to visio's after I got it running and it was doing that, had been doing it with my first alternator, still doing it with the good replacement. Went and looked at it, said fuel pump relay. Since my fuel pump had been rewired at some point off the acc we just unplugged it >.< buzzing stopped. Been driving it around for 3 weeks with no problems, yet that batt light stays on. (has stayed on since I rewired the new alt, and doesn't make any difference either way I wire the 2 plug terminal.) Perhaps I'll replace that relay and hook it back together and see if the light quits.

[MetalFab]

correction, the battery light comes on when the ignition is off, but goes away when the ignition is on. I'm fairly sure it did the same thing when the plug-socket 2 wires were wired the opposite way. I'll switch them again next time I get the gumption to since it charges fine and I'm lazy ^_^