The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 12 AWG red in cab

**71CHEVYSHORTBED402** · 03-09-2017, 06:06 PM

Don't ask me why the thread title says in cab when.......................Yikes.

You're welcome! A fusible link is basically just a short section of smaller gauge wire that (in the event of a short to ground or major overload) will act as a fuse to protect the rest of the wire in the circuit from melting. I see why it's a smaller wire. Good to know.

The fusible link wire has special insulation that is designed to stay intact even when the wire inside burns out. So a quick & easy way to test a fusible link is to give it a gentle tug to see if it feels stretchy (if it does, the wire inside is burned out). Also good to know.

The insulation will often partially melt and give off lots of smoke when a fusible link burns out so they should never be used inside the passenger compartment of a vehicle. Same

One of the biggest differences between a fusible link and an inline fuse is that a fusible link acts like a really slow blow fuse. In other words a fusible link will stand up to short term overloads but still offer protection in the event of a major problem. Makes sense.

That can be an advantage in situations where you don't want a fuse to blow due to a temporary surge in current (such as when an electric motor is started). Quite an education, thank you.

Fusible links also tend to be a bit more compact than a fuse in an inline holder (especially for larger sizes). And not having a fuse holder cuts down on potential loose contact & corrosion issues. Agree.

Those two black rubber boot things you found are inline fuse holders that hold the fuses that protect the ammeter (battery gauge) circuit. They use SFE-4 fuses and replacements are still readily available if you broke one. This application uses fuses instead of fusible links since the current is so small. A fusible link wire small enough to burn out at 4 amps would be way too tiny and delicate to be practical. If I got it right, the circuits with an inline fuse are:

The BLACK/WHITE striped circuit runs from #1 on the cluster to the fuse panel, then to where it's soldered with the 12 AWG reds.

The BLACK circuit runs from #12 on the cluster to the fuse panel and off to the junction block.

03-09-2017, 06:06 PM	#6
71CHEVYSHORTBED402 Senior Member Join Date: Feb 2009 Location: Northern Nevada Posts: 7,118	Re: 12 AWG red in cab - What are these? Don't ask me why the thread title says in cab when.......................Yikes. You're welcome! A fusible link is basically just a short section of smaller gauge wire that (in the event of a short to ground or major overload) will act as a fuse to protect the rest of the wire in the circuit from melting. I see why it's a smaller wire. Good to know. The fusible link wire has special insulation that is designed to stay intact even when the wire inside burns out. So a quick & easy way to test a fusible link is to give it a gentle tug to see if it feels stretchy (if it does, the wire inside is burned out). Also good to know. The insulation will often partially melt and give off lots of smoke when a fusible link burns out so they should never be used inside the passenger compartment of a vehicle. Same One of the biggest differences between a fusible link and an inline fuse is that a fusible link acts like a really slow blow fuse. In other words a fusible link will stand up to short term overloads but still offer protection in the event of a major problem. Makes sense. That can be an advantage in situations where you don't want a fuse to blow due to a temporary surge in current (such as when an electric motor is started). Quite an education, thank you. Fusible links also tend to be a bit more compact than a fuse in an inline holder (especially for larger sizes). And not having a fuse holder cuts down on potential loose contact & corrosion issues. Agree. Those two black rubber boot things you found are inline fuse holders that hold the fuses that protect the ammeter (battery gauge) circuit. They use SFE-4 fuses and replacements are still readily available if you broke one. This application uses fuses instead of fusible links since the current is so small. A fusible link wire small enough to burn out at 4 amps would be way too tiny and delicate to be practical. If I got it right, the circuits with an inline fuse are: The BLACK/WHITE striped circuit runs from #1 on the cluster to the fuse panel, then to where it's soldered with the 12 AWG reds. The BLACK circuit runs from #12 on the cluster to the fuse panel and off to the junction block. __________________ Tony 71 Custom Deluxe, SWB, 2WD, 402, A/C. I developed an assm. guide "kit" for restoring it from ground up. With assys, the guide accts for 1000s of OEM identifications and part numbers, all written in short order. 700+ images include assm, illust., charts, and points of interest. Much of the info. applies to all 67-72 GM trucks, and to a lessor degree all 67-72 GM vehicles. My build thread, and more on the guide https://67-72chevytrucks.com/vboard/...d.php?t=730025