Anyone know what this black plastic cylinder thing is on the positive battery cable going to the alternator? Is it just a junction? You can also see a small cut wire coming out of it.. cut by previous owner.. i believe it goes to radiator fan relay and is supposed to have a fusible link.. is the fusible link maybe in the black cylinder?

 

GM used those cylinders over the splice from a regular wire to a fusible link. In the pic it looks like the fusible link was cut off. The 20 on the cylinder is the wire gauge of the link itself.

With it being 4 gauges smaller then the wire it is protecting, the other wire would be 16 AWG.

RBob.

 

Thank you Thank you.. that's the info i was looking for.. so how do I repair it? Do i need to cut off the black cylinder? Can I splice in somewhere else?

 

If the branch circuit created by the fusible isn't needed (which appears to be the case), your best bet is to replace the battery cable in it's entirety. Unless you're equipped to properly terminate battery cable sized wire, you're better off getting something premade from the local auto parts store.

 

Unfortunately many people who are unfamiliar with the Original Wiring...
Assume that the "Black Cylinder" is the "actual" Fusible-Link, itself.

Obviously this is not the case.
The "Black Cylinder" serves as an Identifier for the Fusible-Link (including stating the Number/ Gauge of the Fusible-Link)...
(You now know that a Fusible-Link is located there... from the Source to the Wire Splice)
Identifying that there is a Fusible-Link attached to the source and Spliced (Butt) to the corresponding Wire.

The "Black Cylinder" also serves as a simple protective device, over the location of the Splice (Butt).

At this Point in time, Blade Fuses had a Maximum Continuous Ampacity of ONLY 40A.
Any Circuit requiring protection at Loads surpassing 40A, would need a Fusible-Link installed.

Now we have many, many Fuse Options that permanently replace (the wonderful little, burn your entire Car and possibly Garage/ House down) Fusible-Links...
With Maxi Fuses, Mega Fuses, ANL Fuses, Etc...

 

Ok.. what do you mean... "the branch circuit created by the fusible isn't needed (which appears to be the case)" ?.. the one that's cut (fusible link missing) should power the rad fan relay.. I'm trying to put that back to original. .. the cable itself is fine.. don't really want to replace whole thing since I'm not able to find exact stock replacement. .. looking to get fusible link from auto parts store and wire to battery.. can i do it this way?

 

Oh nice.... so i can use an in-line fuse instead? What size? More than 40A...

 

If the circuit supplied by the spice is no longer needed then a replacement is the tidiest option.
What did the wire that was originally attached to the "tail" hanging out the splice supply power to? It certainly wasn't the supply for any fan as that would be significantly larger that the remaining bit of the cut off tail. It may have supplied power to the control circuit of the fan relay ( the on/off function). Typically any fan will need a #12 gauge for sufficient power. That's a 20-30 amp deal and the wire size would #12 - #10. Keep in mind that a fan is run through a relay so the fan power (20 amps as an example) is different from what turns the fan on and off via the relay (which can be switched via a small gauge wire).
Vortec makes an interesting point in that fusible links are dinosaurs and now we have the option of providing a proper fuse in its place.
The question is: What did the tail hanging out of the "black cylinder" actually supply power to?

 

it goes to the fan relay

 

There are four wires that go to the relay.
One power wire to run the fan. Positive in and out. (That's two).
One trigger wire (also positive) to turn the relay on and off plus it's ground. (That's the other two).
I'd venture a guess and say that the 20 on the link is the ampacity of the circuit and this was suggested earlier. That being the case, it's what would provide power to the fan itself.
Are the original relays anywhere to be found? I've had 3rd gens that have the relay on the firewall near the master cylinder as well as relays mounted on the passenger side rad support.

 

I just installed a new fan relay .. located front of engine bay pass side in front of air cleaner. ... since the fusible link is missing (or cut).. the orange wire from fan relay was just hanging there not connected.. I'm trying to put i back how supposed to be. Just want to know if i can just wire straight to pos terminal? Does it need fuse? What size?..... thanks.

 

There are several ways to go about this.
The simplest is tap into the positive battery terminal and place a fuse as close as possible. I'd go with #10 gauge wire and a 20 amp fuse. The #10 gives you enough headroom to bump the fuse up to 30 should you need.
The reason for placing the fuse close to the battery is to keep any unfused length of wire as short as possible.
That will take care of power side of the relay.
Hope that helps.


I prefer this style as it has an excellent seal as well as a tab for fastening it to some local sheet metal.

 

The Sealed DELPHI Connector above can be used with short Wire segments of 10AWG or 8AWG Cable for up to a 40A Fuse (ATC/ ATO)...
As it is a Metri-Pack 630 Pull to Seat Connector (Max. Cont. Amp. 46A/ Terminal).

Or the next step up is to a 60A Delphi Connector:




Metri-Pack 800 series, Push to Seat Connector above.


Further steps up are also available.