Re-visiting fusible Link- Very Frustrating

[dmagas]

Hi All,

I have a wire going from the starter to the "junction" relay on Blazer 91 with 6.0 liter LS swap. So this all started when I was disabled in Mesquite Nevada and ended up changing the starter in NAPA parking lot. Long and short it ended up being this wire and pictures are attached with arrows. The temporary fix that a mechanic in Vegas did just to get me home added a in-line fuse. It worked just fine but I would like to replace it and do it right to make sure all connections are sealed and soldered. Everywhere I have asked had many different opinions and honestly no real answers. I can't believe a simple wire can be such a problem! I have been told do not replace with a fuse that is not the same as a fusible link. Ok, well trying to find the link is an issue because they really don't make them all that much anymore because it is old technology. This is what I was told. Fine, I found a couple on line which are not the same; the entire wire is a fusible link with a thick coating on the entire wire. The original had a thicker plastic piece where the "fusible link protection" is and it was closest to the starter. So when I asked about a 12 gauge awg, however the term may be, another hurdle some say 1) do not solder fusible link to regular automotive wire OK. 2) Cannot tell me if I should use the entire strand as fusible and run it from starter to junction. 3) Next, I was told you need a 16 gauge awg fusible because you need to go up 4 to accommodate the amps. Overall, if there is anyone clueful out there on this issue ? I cannot express the appreciation in this effort. Can you use a fuse in-line? What size fuse it has 35 amp now works fine but is it right? If not a fusible link? Entire wire? Can it be solder with regular automotive wire? Sorry for long explanation just wanted to try and provide as much detail as possible. Thank you in advance to everyone!!!!!!!!!

 

[Wes Harden]

You can buy fuseable link wire at part stores. 14ga fuse link 5-6". Splice it into the wire where the fuse holder is. Use a heat shrink butt connector.
The bus bar on firewall. Looks normal to me.
That wire with the yellow plastic bit is also a fuse link.

 

[dyeager535]

1988 light duty truck wiring manual:
"FUSIBLE LINK
A fusible link is a section of wire that is usually four
gage sizes smaller than the circuit it protects. A special
insulation is used that swells when heated by the wire.
Fusible links are usually found in the engine compartment
harnesses. The function of the fusible link is to melt open
when an overload occurs, thus preventing any damage to
the circuit."

"To splice a wire or repair one that is frayed or broken
always use rosin flux solder to bond the splice and
insulating tape to cover all splices or bare wires.
When replacing wire, it is important that the correct size
wire be used as shown on applicable wiring diagrams or
parts book. Each harness or wire must be held securely in
place to prevent chafing or damage to the insulation due
to vibration.
Never replace a wire with one of a smaller size or
replace a fusible link with a wire of a larger size."

I could find nothing in one year of service manual nor the 1988 wiring manual that specifically talks how to wire in a replacement fusible link. But given GM just says solder/wrap for all wire repairs (but does get specific for twisted pair, which is not applicable here) I have to go with them. Four sizes smaller, and solder/wrap the splice.

 

[Wes Harden]

Have to be careful with soldering iron, get to hot and you'll melt the fuse link, or the insulation.

 

[dmagas]

1988 light duty truck wiring manual:
"FUSIBLE LINK
A fusible link is a section of wire that is usually four
gage sizes smaller than the circuit it protects. A special
insulation is used that swells when heated by the wire.
Fusible links are usually found in the engine compartment
harnesses. The function of the fusible link is to melt open
when an overload occurs, thus preventing any damage to
the circuit."

"To splice a wire or repair one that is frayed or broken
always use rosin flux solder to bond the splice and
insulating tape to cover all splices or bare wires.
When replacing wire, it is important that the correct size
wire be used as shown on applicable wiring diagrams or
parts book. Each harness or wire must be held securely in
place to prevent chafing or damage to the insulation due
to vibration.
Never replace a wire with one of a smaller size or
replace a fusible link with a wire of a larger size."

I could find nothing in one year of service manual nor the 1988 wiring manual that specifically talks how to wire in a replacement fusible link. But given GM just says solder/wrap for all wire repairs (but does get specific for twisted pair, which is not applicable here) I have to go with them. Four sizes smaller, and solder/wrap the splice.

Thank you. It sure would be nice if they would just sell a replacement.

 

[Wes Harden]

You don't want to replace that whole wire. It goes into the loom, and has a splice that feeds 2 different directions.
The Fuse link you get at part store is the replacement.

 

[dyeager535]

Maybe this link will work? Not saying the first one (I see Dormant 85627) is correct, but it shows the "assembly" of wire and fusible link. You solder that section in as a replacement for yours that burned up.

Electrical > Fuse > Fusible Link | Shop Now at RockAuto

Electrical Parts and More for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

Never had to mess with one, no idea how they are in the wiring harness from GM, whether built as one long run, or if the fusible link section was spliced in even when new.

 

[dmagas]

Maybe this link will work? Not saying the first one (I see Dormant 85627) is correct, but it shows the "assembly" of wire and fusible link. You solder that section in as a replacement for yours that burned up.

Electrical > Fuse > Fusible Link | Shop Now at RockAuto

Electrical Parts and More for Your Vehicle at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

Never had to mess with one, no idea how they are in the wiring harness from GM, whether built as one long run, or if the fusible link section was spliced in even when new.

Thank you

 

[dmagas]

You can buy fuseable link wire at part stores. 14ga fuse link 5-6". Splice it into the wire where the fuse holder is. Use a heat shrink butt connector.
The bus bar on firewall. Looks normal to me.
That wire with the yellow plastic bit is also a fuse link.

Man thank you !

 

[dmagas]

You don't want to replace that whole wire. It goes into the loom, and has a splice that feeds 2 different directions.
The Fuse link you get at part store is the replacement.

One last question, does that wire look like it 12 gauge or 10? I believe it is 12 but not 100% sure.....

 

[Wes Harden]

The fuse hold is maybe 12ga probably 14ga. You need to size the original truck wire, and go from there.

I have done more than a few. The oem is a splice, then a large plastic bead is molded over the splice. Just like the yellow head on the wire in your picture.
When I have done them in the past. I used a 10ga butt connector with the stink tube included. Many people, myself included, don't like butt connector for 2 different ga wires. They do make special butt connectors to accommodate 2 sizes. I always had to special order them, from places like Grainger McMaster Carr, Kimball Midwest, etc.
So I use the size that fits the larger ga, and then strip more insulation from the smaller ga, fold the exposed conductor over. This way the conductor fills the larger size butt connector.
Sounds like a lot, but really isn't.

 

[dmagas]

The fuse hold is maybe 12ga probably 14ga. You need to size the original truck wire, and go from there.

I have done more than a few. The oem is a splice, then a large plastic bead is molded over the splice. Just like the yellow head on the wire in your picture.
When I have done them in the past. I used a 10ga butt connector with the stink tube included. Many people, myself included, don't like butt connector for 2 different ga wires. They do make special butt connectors to accommodate 2 sizes. I always had to special order them, from places like Grainger McMaster Carr, Kimball Midwest, etc.
So I use the size that fits the larger ga, and then strip more insulation from the smaller ga, fold the exposed conductor over. This way the conductor fills the larger size butt connector.
Sounds like a lot, but really isn't.

I believe the fuse hold is actually 16. I believe the red wire is about a 10. Thank you I think I have a plan now. Where I got confused is they sell 12 gauge fusible link so I thought the little black end was the fuse part of the wire but the actual wire is 12 gauge if that makes sense. In that case as all the suggestions have been you go up 4? A 10 gauge would require a 14 gauge wire. Correct me if I am wrong that is how I am understanding it. Thank you for your time.

 

[Wes Harden]

Yes 14 ga is common fuse link size, and would be appropriate for 10ga

 

[rampage]

I believe the fuse hold is actually 16. I believe the red wire is about a 10. Thank you I think I have a plan now. Where I got confused is they sell 12 gauge fusible link so I thought the little black end was the fuse part of the wire but the actual wire is 12 gauge if that makes sense. In that case as all the suggestions have been you go up 4? A 10 gauge would require a 14 gauge wire. Correct me if I am wrong that is how I am understanding it. Thank you for your time.

Yes, the larger the AWG number the smaller the wire diameter.

 

[wazzabie]

I cut a fusible link from the junk yard below the factory clear/yellow crimp so I have the correct gauge and length of wire.