Lights Under fuses

[mamestra]

We have been have some electrical problems and now I can't remember if the red lights under the fuses should be lit or not. Presently we don't have any lights on under the fuses and I'm not sure if the lights are on and only go off if a fuse is blown or are they off and only light up when a fuse is blown. So for those that know which way is it?
Thanks
Michael

[Irlpguy]

On mine the red light is on when the fuse is blown. 2012 - 3402RL So it's a good thing with no red lights on...

[mamestra]

Thanks, we had blown a fuse and had no red lights on, the service manager stated that the fuse that blew also controlled the lights, that seemed too weird so I thought that I had better ask.
Thanks again
Michael

[Irlpguy]

That explanation does seem strange Michael, and I don't buy it. You could take a blown fuse and test one of the circuits by replacing a good fuse with the bad one.

I will see if I can find the schematic for mine and see how that is wired, it makes no sense to have one fuse affect all the other circuits, I seriously doubt that is the case.

[Irlpguy]

Michael it is my humble opinion the service manager was incorrect. I do not know what model you have but ours is the PD4590 Progressive Dynamics "all in one system" and the red fuse blown LED's are an option. It is possible your unit does not have that option but if it has the LED's at one end of each fuse then it should indicate a blown fuse. There is no indication on the schematic that one fuse controls the rest of them. Try doing as I suggested and replace a good one with a bad one and see what happens.
Good luck.

[jimcol]

I have not seen a schematic but it is my understanding that the red light will only be on if the fuse is blown and something beyond the fuse is calling for power. Jim

[H. John Kohl]

OOPS did not see Jimcol post until after I reread this. I agree.

quote:Originally posted by mamestra

Thanks, we had blown a fuse and had no red lights on, the service manager stated that the fuse that blew also controlled the lights, that seemed too weird so I thought that I had better ask.
Thanks again
Michael

The Red LED WILL LIGHT when the Fuse is blown. However, it will only light if the circuit it supports is trying to draw current (be turned on). An example is if the fuse supports a light on a switch. The LED will not be on until the switch is turned on trying to turn on the light, therefore drawing current.

I do know this from experience. I could not understand why the LED was intermittent on and off when I first started trouble shooting the problem.

So the LED is lite only if the two things are present.[list_to_fix][*] The fuse is blown[*] The circuit is trying to do its job provide current.

[mamestra]

Thanks John and Jim
That certainly makes sense, the fuse that had blown controlled the overhead lights in the kitchen, and are controlled by a door switch, which was bad, and a light switch in the cabinet where the slide controls are, so it is quite possible that I hadn't looked at the led panel when the switch was on. By the way my model is 2012 3750FL.
Michael

[BB_TX]

The blown fuse light (LED) is typically wired in parallel to the fuse.
If the fuse is good, there is no voltage drop across the LED and it will not turn on (i.e. the voltage is the same on both sides of the LED).
If the fuse is open, then there is a voltage drop across the LED and it will turn on (i.e. the hot side of the LED is +12v and the other side is grounded thru the appliance circuit). The LED is such a high resistance device that the resulting current thru the appliance is minimal.

[Irlpguy]

Both Jim and John brought up something I forgot to mention, the LED will only come on if the fuse is bad and there is a current draw on that circuit. Some will come on if you pull the fuse because they have something connected to them at all times, like smoke detectors.

I still cannot see where if one specific fuse is bad it will affect the operation of all the others.