new type of blade fuses?

[muleys86]

I'm goin down the road one evening in my 86 Scottsdale, dimmed the lights and the gauge lights go out but a light comes on shining on my feet. I brightened/dimmed again and gauge lights came back on, floor light goes out.
No problem. Did it again tonight. Getting home I stuck a mirror under the dash to look and lo and behold the fuse is lit up! Ive never seen these as the fuses have a bump in the center where the amp number is. That was the light under the dash. When I pulled the fuse out the blade stayed in the slot. Pulled that out, replaced the fuse with a regular fuse, lights are normal. There is another fuse in the box like that one. Are these type of fuses common? It was definitely blown, don't know why the first time the light went out then came back on. The light from the fuse itself to let one know its blown? Btw, the taillights were out also. Am I slow to catch up with new technology? Muley

 

[1987 GMC Jimmy]

I'm goin down the road one evening in my 86 Scottsdale, dimmed the lights and the gauge lights go out but a light comes on shining on my feet. I brightened/dimmed again and gauge lights came back on, floor light goes out.
No problem. Did it again tonight. Getting home I stuck a mirror under the dash to look and lo and behold the fuse is lit up! Ive never seen these as the fuses have a bump in the center where the amp number is. That was the light under the dash. When I pulled the fuse out the blade stayed in the slot. Pulled that out, replaced the fuse with a regular fuse, lights are normal. There is another fuse in the box like that one. Are these type of fuses common? It was definitely blown, don't know why the first time the light went out then came back on. The light from the fuse itself to let one know its blown? Btw, the taillights were out also. Am I slow to catch up with new technology? Muley

Yeah, I bought some of those the other day not noticing. They are, in fact, supposed to light up when a fuse blows to tell you that it did. I think it's pretty cool, but I only found out about it a month or two ago, myself. It sounds like you may have a short in your lights or something, buddy.

 

[chengny]

They are fairly new. They are supposed to confirm that the fuse has blown and also it's location in the fuse block.

From Little Fuse:

Smart Glow indicator fuses are innovative automotive style fuses
(ATO, Mini, Maxi and glass tube) that feature an indicator light that
glows when the fuse is blown, saving time to troubleshoot an open
circuit.

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Theory of operation:

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An LED indicator light circuit is connected between the blades of a blade fuse in parallel with the fuse link. When the link melts, the LED lights to indicate a blown fuse.

When these fuses first came into use they only used one diode, so correct polarity was critical for them to operate properly. If inserted with the polarity of the lone diode positioned counter to the polarity of the protected circuit, it didn't work. If the fuse blew, it was like any other ordinary fuse - you could only identify it as blown by looking closely at the element (or checking it for continuity with your meter).

Now they come with two diodes, each facing in the opposite direction from the other. This feature eliminates the possibility of inserting the blades of the fuse in the wrong slots. Before this technology was developed, if a single diode indicator fuse was used, and it was inserted backwards, and the fuse blew, the diode wouldn't illuminate.

Parallel dual bipolar light emitting diode (LED) indicators are in series with an integrated resistor. The fuse may be inserted in either direction without concern for polarity. The indicator light circuit may be built into a blade fuse, or snapped onto an existing blade fuse as an attachment.



From one of the original patent applications:

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A blown fuse indicator light device for a vehicle fuse, the device comprising:
a blade fuse comprising two insertion blades insertable in an electrical circuit to complete the electrical circuit and a fuse link forming an electrical connection between the blades, the fuse link adapted to blow out when an electrical overcurrent exceeds a normal capacity of the electrical circuit in order to prevent damage of any portion of the electrical circuit;


An indicator light circuit forming an electrical connection between the blades in parallel with the fuse link, the indicator light circuit comprising a resistor connected in series with a parallel circuit comprising one of a pair of alternately facing polar light emitting diodes in each of the lines of the parallel circuit to form a dual bipolar light emitting diode indicator having a single integrated resistor which drops an applied voltage between the blades to a required voltage necessary to cause one of the pair of light emitting diodes to light, the dual bipolar light emitting diode configured to complete an electrical connection between the blades when the fuse link is blown out thereby lighting one or the other of the light emitting diodes depending on the direction of a flow of electricity in the second electrical connecting element, thereby providing a blown fuse indicator light which functions regardless of a direction of flow of electricity through the fuse blades so that the fuse may be installed without regard to polarity.

 

[highdesertrange]

actually they have been around awhile. the patent was issued in the 1970's. true recently they have become more widespread. highdesertranger