Dwayne 76

I've noticed that when I turn the lights on, the RPM gauge increases. Also, when the lights are on I've discovered a buzzing sound emitting from a little black box by the fuse panel, that has a wire or two going into it from the LPS socket on the fuse panel. This just started two days ago.

SteveG75

The buzzing sound is the lights warning buzzer. It should come on with lights on and ignition off. If it comes on with the ignitionon then you probably have a ground problem somewhere.

Same with the lights/rpm problem Probably a ground problem somewhere. I know that my rpm does funky things too with lights and fans on/off. :crazy:

Dwayne 76

I know the lights on warning buzzer, it comes on, but with engine running and lights turned on this little black box by the fuse panel starts to buzz. The lamps on warning buzzer is on the passenger side just under the dash.

SteveG75

I wonder if your wiring has been "bubba-ized". What you described is exactly the wiring and location of the warning buzzer in my '75. :confused:

Dwayne 76

Ok, quick question. Does the buzzer on your car have the following on it:
Hobbs Div. SW.
864079

U.S. Patent 3768153

If so, I really need to know what that is suppose to plug into. I found it dangling, looks like it has a male connector on it, but can't find where it goes.

TIA

SteveG75

I am not sure about numbers since I haven't really got under there that much. Plus, since everything seems to work most of the time, I try to avoid screwing with it. :crazy:

I wouls say the tach problem is probably either a bad connection or bad ground. I do know that my tach is sometimes screwy until I jiggle the lead a little. (I just can't be bothered to pull the whole thing out since I have alrready lived throught that pain once before. :smash: )

Sorry, kinda running out of ideas. :(

Maxx76

Hi,
I've had a similar story with this box. Same writing on it, HOBBS DIV. SW, etc.
I had this buzzing sound all the time with lights ON. (just got the car, fixing bugs one at a time, 1976 L48)
I found the sound coming from the box, an there was one wire missing from the top (two wires enter from bottom).
AND there was a Pink wire hanging out by himself.
So I plugged the pink wire, and the buzzing is gone. BUT now, if I turn off the ignition switch with lights ON, the car doesn't stop !
I need to switch off the lights to kill the engine !!
Any idea which wire should go there, and what to do with this pink wire ?
Thanks.

Peterbuilt