Fusible link question
05-05-2008, 02:57 PM
#1
Burning Brakes
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Fusible link question
I have had a battery charging problem. All electricity in the car will die with a new alt and battery. Neg terminal tightly on starter and small neg wire has a clean ground.
I noticed the fusible links behind the battery (red wire to alt) have turned brown and nasty looking (black connections interchanging the wires with the links). All the actual red wireing is intact. Im figuring that means they are burned?
I noticed the fusible links behind the battery (red wire to alt) have turned brown and nasty looking (black connections interchanging the wires with the links). All the actual red wireing is intact. Im figuring that means they are burned?
Last edited by cplonner; 05-05-2008 at 03:28 PM.
05-05-2008, 03:31 PM
#2
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Yes, you need to cut it back to were it's all copper and not fusible link.
You also need to get the right size for your year.
On my 1995 there's two link.
One blows, it won't charge.
The other blows it over charges.
Here's a photo of the mess I found.
It actually melted into the battery!
You next task will be to find the short that caused it to blow in the 1st place.
You also need to get the right size for your year.
On my 1995 there's two link.
One blows, it won't charge.
The other blows it over charges.
Here's a photo of the mess I found.
It actually melted into the battery!
You next task will be to find the short that caused it to blow in the 1st place.
05-05-2008, 03:40 PM
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Not possible to blow a fusible link and have the battery overcharged. The alternator has a voltage regulator built in that attempts to maintain the proper output voltage, which cannot overcharge a battery.
If you can find out the current level at which the fusible link blows, you can look up on a wire chart and determine what size wire that fuses (melts) at that current and use that size copper wire as the replacement fusible element. Otherwise go to a parts store and ask for a replacement link at the location yours burned out.
If you can find out the current level at which the fusible link blows, you can look up on a wire chart and determine what size wire that fuses (melts) at that current and use that size copper wire as the replacement fusible element. Otherwise go to a parts store and ask for a replacement link at the location yours burned out.
05-05-2008, 04:06 PM
#4
Burning Brakes
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I may have fixed the problem that caused the link to burn, I got another alt. just had an extra. So if somthing was wrong with the alt. it shouldnt be anymore. Im gonna try changing out these links.
05-05-2008, 04:44 PM
#5
Le Mans Master
Some info on fusible links from past threads
Fusible Link Amp Rating
Fusible Links
As mentioned in the first link, fusible link wire is packaged according to
the gauge of the wire it is intended to protect.
Also, the FSM denotes wire in metric units. If you need assistance in
converting to AWG, post the FSM's metric size of the wire to be
repaired.
.
Fusible Link Amp Rating
Fusible Links
As mentioned in the first link, fusible link wire is packaged according to
the gauge of the wire it is intended to protect.
Also, the FSM denotes wire in metric units. If you need assistance in
converting to AWG, post the FSM's metric size of the wire to be
repaired.
"Metric wire size 2.0 is equivalent to 14ga AWG. Metric wire size 5.0 is
equivalent to 10ga AWG. (A fusible link is typically four AWG numbers
smaller than the conductor it is intended to protect - a 14 ga protects
a 10 ga.) Determine the amps the 14 ga will fail at and that gives a
ceiling for the circuit, I suppose. I've read that Resistance per Lineal
Foot of 14 AWG is 0.0028 ohm. Perhaps Ohms Law would help produce
an estimate."
equivalent to 10ga AWG. (A fusible link is typically four AWG numbers
smaller than the conductor it is intended to protect - a 14 ga protects
a 10 ga.) Determine the amps the 14 ga will fail at and that gives a
ceiling for the circuit, I suppose. I've read that Resistance per Lineal
Foot of 14 AWG is 0.0028 ohm. Perhaps Ohms Law would help produce
an estimate."
.
05-05-2008, 04:44 PM
#6
Le Mans Master
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St. Jude Donor '05-'06
An alternator will not cause the link to blow a shorted wire will. You need to get a VOM and learn to use it to test the link. Also a FSM so you can look at the wiring diagrams.
05-05-2008, 05:58 PM
#7
Burning Brakes
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Ok so i just changed out the connections to the fuseable links and cranked her up. So far the battery has been holding a charge but im going to keep checking it.
05-05-2008, 06:09 PM
#8
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You can tell the state of charge of a car battery by measuring its voltage at the battery terminals under no load. 12.0 volts and below, discharged. 12.9 volts and above, fully charged and linear in between.
05-06-2008, 08:38 AM
#13
Burning Brakes
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Ok its 12.45 on my voltimeter with everything off. I made a mistake before and actually had the power on. I checked it with just the power on and it was 12.2.
05-06-2008, 09:11 AM
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Not possible to blow a fusible link and have the battery overcharged. The alternator has a voltage regulator built in that attempts to maintain the proper output voltage, which cannot overcharge a battery.
If you can find out the current level at which the fusible link blows, you can look up on a wire chart and determine what size wire that fuses (melts) at that current and use that size copper wire as the replacement fusible element. Otherwise go to a parts store and ask for a replacement link at the location yours burned out.
If you can find out the current level at which the fusible link blows, you can look up on a wire chart and determine what size wire that fuses (melts) at that current and use that size copper wire as the replacement fusible element. Otherwise go to a parts store and ask for a replacement link at the location yours burned out.
Undervolt for one, overvolt for the other.
05-06-2008, 10:43 AM
#15
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Post the information straight out of the FSM, I still don't buy it. Nothing external to the alternator controls the output voltage, the internal voltage regulator determines the alternator output voltage. A fusible link blown can turn off the alternator, but nothing external can increase the alternator output voltage.
