Fusible links part II

[Jesse Jaymes]

Appreciate the assistance. One poster listed step by step instructions to follow to track down the problem.

I attempted a quick fix this evening and ran out of time and light.

I purchased a new positive bat cable and installed it, as well as took off all of the wires to the starter and checked for fusible links and faults.

I did not find any faults with the fusible links that I could tell.

I got about 14v at the battery, which was not able to crank the truck to start it. THought this was odd.

I had 13-14v at the large post on the starter solenoid on top of the starter. I had nothing at the positive post of the alternator. On the two plug/two wire plastic plug I had 13 on one post and nothing on the other(turned off).

So I hooked up a large battery charger with a jump setting to start the truck. I got lots of sparks and the interior volt meter was at 13ish. Cranked right up and the meter held at 12ish while running. Pulled the jump cables and we were right back to 9 and falling. Went back to put the cables on while running and got major sparkage on both the pos and neg.

Does this help at all in determining what I have going on?

 

[Lunatic]

I did not find any faults with the fusible links that I could tell.

....That you could tell.... Leads me to believe you physically inspected them with your hands and eyeballs. If they are in a plastic jacket, physical isnt gonna tell you anything other than "there they are".

Did you ring them across with a meter ? Verify that they are still solid before moving forward.

Both of the leads to the alternator connector should be hot with the ignition on, only one hot with the ignition off, and only one hot when the truck is running.

And the larger wire to the back of the alternator (on the stud) should always be hot.


Lastly, this is your original thread / problem. Starting a new thread just opened the door for repeat possibilites and solutions.


Good luck


Lunatic
FtHood, TX

 

[Jesse Jaymes]

Appologize, just scrambling to find and fix the headache. Between local co-workers, internet and manuals, I have about 10 possibilities.

Yes, got under there and inspected with eyeballs and hands. No, did not do a meter reading.

I was told to expect what I thought were 2-3" sections of wire that were heat shrink tubed and more flexible than regular wire. Guess I got one of those.

I was told that if the fusible link was blown it would be easily stretched by hand.

I did not find this to be true, so assumed they were good.

Connected to the starter was the large gauge from the pos terminal. I replaced this for good measure.

Two wires in a connector which terminated in an eye that was also located on the same stud as the positive batt cable. Then a smaller, fusible link looking fellow that looked much like your picture connected to a very small and frail post that took a 9mm to get the nut off.

Think I had 14v at the batt, then 14 v at the positive stud on the starter. Bout as far as I got with the meter.

I do not think I had 14 back at the Alternator pos stud.

The plugs did read 13ish and no reading for the plug and play pair.

The 14v in the battery, which couldn't turn the truck over baffled me from the onset and pretty much wiped any thoughts of anything I was going to do from working out almost immediately.

If you would explain how to check the fusibles with the meter, I would certainly listen and try and get a reading.

There was no splice that I was expecting at the fusible like I was suspecting. If I chose to simply replace it, do I just lop off about 3" of the plastic fusible and splice in my new deal?

 

[apache]

You mentioned sparks flying........ first this is not right and a indication of a direct short somewhere...gotta be. Goin back to cables just to be clear here. We have a compressor with JD 4 cyl,new battery,cables looked like new. Voltages,tests looked good,hit start and nada. after much pokin around both cables were replace and the issue was gone.
On to the rest, Older chevys are notorious IMO for having bad starter solenoid gremlins especially the way many old type headers were run which were to close and caused to bendix to fry. The hot spots would not make contact and sometimes jumping the rig would cause enoght "jolt" to make it catch and fire up otherwise it seemed a few good wacks with a bar or on the solenoid would do the trick. Kinda grabbin at straws here but has the starter been checked for shorts etc,again if theres sparks flyin theres something wrong and a bad short is present. Id for one avoid jumping with another car to prevent damaging of somebodies alternator/electrics/computer.

 

[Lunatic]

To "ring out" any circuit, linked or not - Just grab a multi-meter and put it on the OHMs setting (symbol: Ω). Touch your two meter leads together and you will get a resistance reading. This is commonly referred to as "ring out" because with the meter tone on, a completed (good) circuit will make the meter tone ring. A broken/open circuit will not ring.

There are many fusible link styles. The one described as "shrink wrapped" is just another type. Being able to flex it is normal - Being able to fold it over (in half) with no physical resistance is not normal and would indicate a blown link.

So, 101, back to basic troubleshooting. Disconnect your battery.

From your starter wires, disconnect the solenoid. Trace you wire lines to where-ever they end up. One should be going to the alternator connector, and another to the firewall below you brake booster cylinder (IIRC) on the fuse block. I had 3 total, as you saw in the fusible lnk picture. Find the other ends of each wire you have.

Grab a spare piece of known good wire and connect it to individual wire in question. Take the other end of your jumper wire to one of your OHM meter leads. Put your other OHM meter lead to the other end of the wire in question. If it "rings", youre good. If not, the link is blown, and theres your problem. Check your other wiring in question.

Electrical problems are not known to be fun nor quick about being fixed. Stick it out and cover all bases. Dont skip. Dont assume. Eventually, you will find the issue causing your battery drainage.


Let us know what you find - And good luck !


Lunatic
Ft Hood, TX

 

[JDNobodi]

Sound like you have an "open" wire somewhere which could be a fusible link.
Looking for a parasitic draw would be a waste of time, but you could get lucky.

....That you could tell.... Leads me to believe you physically inspected them with your hands and eyeballs. If they are in a plastic jacket, physical isnt gonna tell you anything other than "there they are".

Did you ring them across with a meter ? Verify that they are still solid before moving forward.

Both of the leads to the alternator connector should be hot with the ignition on, only one hot with the ignition off, and only one hot when the truck is running.

And the larger wire to the back of the alternator (on the stud) should always be hot.

I agree with Lunatic here.

I've fought with fusible links before and sometime the link looks physically good. Sometimes moving a wire you get a "reaction" like sparks or the circuit suddenly working. You’re going to have to use the meter to verify the link or wire is good.

 

[Jesse Jaymes]

Well, I only got to work on it for a very short time this am in the light. Shift rotation, 12p-10a.

I am so close in my mind to having it figured out, but I am lacking that last push over the edge.

I will list some numbers I got for readings and I would guess you all would have it figured out for me.

Batt=14v(resting)
Connection at starter-pos cable(just replaced it for good measure)=14
Two-prong alternator plug at alt(key off)=14v on left plug 0 on right


Now...with this plug in place on the alternator, I only have between 2-3 coming off the metal eyelet wire on the positive stud off the alternator. I was pretty certain that this was supposed to be 14v constant? I believe this was a key on reading.

That wire runs up to what I am calling the busse box on the firewall. Has 3 red wires on the studs by what look to be 7/16 nuts.

Outer most on the pass. side has 14v constant. The middle has 2-3(this is the wire connected to the pos stud on the back of the alternator). And the outer most towards the drivers side has zero juice (maybe key was off?)

So did this solve anything? Looks like I have 14v going into the alternator, but only 2v coming out? Possible?

Also, found a negative ground strap that is hanging. It's coming off the body just under the AC unit. It's dangling into nowhere. I have no clue where this is supposed to go. Ran out of time and didn't think about it till I was driving to work.

I have a neg cable(large gauge) coming off the neg term of the batt. This attaches to the top of the alternator bracket. I cleaned all paint off of this and reattached a while ago.

I have a small gauge wire coming off the neg batt terminal also. I think this one is grounded to the inner fenderwell, but can't be sure.

So would this dangling ground need to be body (which it is stemming from) to frame???

Thanks at least for continuing to read and bear with me. It is frustrating, as I do not have a local Chevy mentor, and I didn't grow up turning wrenches, and I have NEVER been a fan of electricity. So I never messed with the toaster to see what made the wires hot.

 

[Jesse Jaymes]

Lunatic-

I've read your explanation of how to test or ring out. I think I totally understand what you are telling me and will attempt to put it into practice as soon as I can if the problem cannot be solved with my findings I posted above from this AMs twice over.

 

[ryoken]

fusable links bring the suck..... I'll take resettable breakers anyday...

eng to body grd strap is critical... the other small one off the battery should go to the rad support...

 

[bp71k5]

Now...with this plug in place on the alternator, I only have between 2-3 coming off the metal eyelet wire on the positive stub off the alternator. I was pretty certain that this was supposed to be 14v constant? I believe this was a key on reading.

the positive lug on the alternator should always be hot and full battery voltage. If it isn't at least12v, then trace the wire back and find where it's broken.

Also make sure you didn't connect the wire to the ground lug instead of the bat+ lug.

 

[Jesse Jaymes]

Brian-

I guess you have me confused? The alternator only has two sets of wires connecting it to anything.

Two wires are in a plastic plug. They both go to the starter/solenoid.

The other goes from what I am calling the positive stud on the alternator, up to a busse box on the firewall.

This is not the same as my (limited) experience where a wire will connect from the alternator to the positive terminal of the battery.

Still getting more confused. THought I had it there for a minute.

 

[Lunatic]

the positive lug on the alternator

Thats what he's referring to yeah - You have 3 wires total. 2 in a connector and one larger gauge to a stud on the back of the alternator. The lone wire should always be hot, and one of the connector wires should always be hot.

After you ring your circuits, hook everything back up (Assuming you didnt find the issue) and then start the truck - Check all three wires for voltage, post your readings.


Good luck !


Lunatic
Ft Hood, TX

 

[ryoken]

After you ring your circuits,

hmmm, new term for me.... continuity test is what I've always said/heard... have to use that one on my boss this week, "yeah, I rang the circuits, we're good!"

 

[Lunatic]

hmmm, new term for me.... continuity test is what I've always said/heard... have to use that one on my boss this week, "yeah, I rang the circuits, we're good!"

LOL

Its actually not an automotive term - I brought it with me from my days as an electrician. But same / same.


Lunatic
Ft Hood, TX

 

[British Slave]

Did you get it fixed?