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FUSIBLE LINKS; replacement? by AL87
Started on: 08-29-2013 11:58 AM
Replies: 18 (3303 views)
Last post by: thesameguy on 09-04-2013 01:22 PM
AL87
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Report this Post08-29-2013 11:58 AM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
I was wondering what I should replace the fusible links with.

I want to get something that, if the fuse blows, I can just pop another one in.

I dont know the amp ratings for any of them, if someone could help?

I'm in a bit of a pickle, I had a bad ground connection to my negative battery terminal, and the ground wire coming off the battery
with the fusible link got so hot it burnt up from the inside out, I later discover there was also some corrosion that got in and started to play with the wire as well. I'm looking to replace that if anything, and I cant reuse the fusible link because the wire milted and broke right at the end od the fusible link.
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TONY_C
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Report this Post08-29-2013 01:06 PM Click Here to See the Profile for TONY_CSend a Private Message to TONY_CEdit/Delete MessageReply w/QuoteDirect Link to This Post
You should only replace a fusible link with a fusible link.
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Pyrthian
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Report this Post08-29-2013 01:45 PM Click Here to See the Profile for PyrthianClick Here to Email PyrthianSend a Private Message to PyrthianEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by TONY_C:
You should only replace a fusible link with a fusible link.


yup. there is a reason fuses are not used there in the first place.
fusible links are more like a "slow-blow"
and, it is a pretty cheap & easy thing to do.
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jhgraham
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Report this Post08-29-2013 01:56 PM Click Here to See the Profile for jhgrahamClick Here to visit jhgraham's HomePageClick Here to Email jhgrahamSend a Private Message to jhgrahamEdit/Delete MessageReply w/QuoteDirect Link to This Post
If I remember correctly, you can replace Fiero fusible links with a piece of 24 gage copper wire. The service manual references this method. Please verify.
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AL87
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Report this Post08-29-2013 02:43 PM Click Here to See the Profile for AL87Click Here to Email AL87Send a Private Message to AL87Edit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jhgraham:

If I remember correctly, you can replace Fiero fusible links with a piece of 24 gage copper wire. The service manual references this method. Please verify.


I'll have to find my gm shop manual... XD

also... I looked at all my other fieros sitting here, and I noticed something...

NONE OF THEM HAVE A FUSIBLE LINK ON THE SMALL GROUND WIRE GOING TO THE NEGATIVE BATTERY TERMINAL*

so I chopped my wiring up and cleaned everything and put it all back together. and so far... soo good!
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jhgraham
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Report this Post08-29-2013 03:39 PM Click Here to See the Profile for jhgrahamClick Here to visit jhgraham's HomePageClick Here to Email jhgrahamSend a Private Message to jhgrahamEdit/Delete MessageReply w/QuoteDirect Link to This Post
Fusible Link-Replacement

1) Disconnect battery
2) Locate burned out link. This may require
use of the chassis wiring diagram.
3) Strip away a melted harness insulation
4) Cut burned out link ends from circuit
5) Strip circuit wire back approximately ½ inch
to allow soldering of new link.
6) Using fusible link (copper wire) four gages
smaller than the protected circuit and approximately
10 inches long, solder new link into circuit.


From Fiero Service manual.
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TONY_C
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Report this Post08-29-2013 04:31 PM Click Here to See the Profile for TONY_CSend a Private Message to TONY_CEdit/Delete MessageReply w/QuoteDirect Link to This Post
It should be wiore specifically made for fusible links, not just wire that is 4 gauges smaller. The fusible link wire has a special insulation that will smolder and not catch fire.
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jhgraham
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Report this Post08-29-2013 05:43 PM Click Here to See the Profile for jhgrahamClick Here to visit jhgraham's HomePageClick Here to Email jhgrahamSend a Private Message to jhgrahamEdit/Delete MessageReply w/QuoteDirect Link to This Post
I don't think so....they use copper wire. Fusable links are used to protect the wiring so that the weakest location/portion will burn out if EXTENDED high current exist. You can not pass the same current through 24 gage and 20 gage because the 24 wire will burn up. Fusable links are not fuses as we know them, they are emergency current protectors. They are slow acting links. They are only to help us should a prolonged high current problem exist, stalled motor etc., They protect the wires so that we do not need to replace the entire wire harness.
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carbon
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Report this Post08-29-2013 06:37 PM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
Fusible links are crimped not soldered. They are also made of a particular strand count wire that isn't just smaller gauge... that is why fusible link wire is sold as fusible link wire.
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jhgraham
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Report this Post08-29-2013 07:55 PM Click Here to See the Profile for jhgrahamClick Here to visit jhgraham's HomePageClick Here to Email jhgrahamSend a Private Message to jhgrahamEdit/Delete MessageReply w/QuoteDirect Link to This Post
Negative.

I have been wondering why there are so many opinions on fusible links. We seem to forget our cars were manufactured in 84-88 when engineering was simplification and cost effectiveness. If we choose to search the internet for fusible links we come up with exotic details, non that relate to our old vintage engineered Fiero’s. We espouse data that is current and does not include their engineering conclusions even when their manuals state facts. It makes us feel important to espouse our knowledge, but it is often off tract as to what we need. I believe we need to trust the Fiero manuals and accept their engineering; it was as good as it gets for the times and offers simplistic solutions. Yes today we engineers would call for exotic materials; we all want our design inputs. Confusion ranks supreme.

Have at it.

[This message has been edited by jhgraham (edited 08-29-2013).]

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carbon
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Report this Post09-03-2013 02:39 PM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by jhgraham:

Negative.

I have been wondering why there are so many opinions on fusible links. We seem to forget our cars were manufactured in 84-88 when engineering was simplification and cost effectiveness. If we choose to search the internet for fusible links we come up with exotic details, non that relate to our old vintage engineered Fiero’s. We espouse data that is current and does not include their engineering conclusions even when their manuals state facts. It makes us feel important to espouse our knowledge, but it is often off tract as to what we need. I believe we need to trust the Fiero manuals and accept their engineering; it was as good as it gets for the times and offers simplistic solutions. Yes today we engineers would call for exotic materials; we all want our design inputs. Confusion ranks supreme.

Have at it.



I am going by Helm's factory service manual for the 1988 Pontiac Fiero... what are you going by? The fusible link wire also has insulation designed to contain flame or spark when they fail, standard wire does not.

Edit: Here is a spec from Delphi on fusible link requirements

Usually, when trying relate information to people it is better to not be condescending.

[This message has been edited by carbon (edited 09-03-2013).]

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phonedawgz
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Report this Post09-03-2013 03:04 PM Click Here to See the Profile for phonedawgzClick Here to visit phonedawgz's HomePageClick Here to Email phonedawgzSend a Private Message to phonedawgzEdit/Delete MessageReply w/QuoteDirect Link to This Post
Unswitched power to the Fiero ECM is protected by a fusible link. Unswitched power to the ECM is the power source for the ECM. Switched power is only 'sensed' by the ECM. Clearly this would be better served by a fuse rather than a fusible link. By the way GM did chose to fuse the switched power to the ECM.

Power to the ignition system is protected by a fusible link at C500, and then only on some Fieros. Clearly this is the result of some very poor engineering. Again this system would be better served by a fuse, and that fuse should be located near the power source (the ignition switch) rather than half way along the wire to the ignition coil & ICM.

In both examples listed above GM in later years switched to fuses to protect these circuits.

-----

In regards to the OP's original post. The negative battery cable to frame isn't supposed to have a fusible link on it.

-----

Before considering the Fiero wiring engineers as gods, remember these are the guys who after five years still couldn't figure out how to get the 'Check Bulb' function to work correctly on the TEMP light.

[This message has been edited by phonedawgz (edited 09-03-2013).]

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carbon
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Report this Post09-03-2013 03:24 PM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by phonedawgz:

Before considering the Fiero wiring engineers as gods, remember these are the guys who after five years still couldn't figure out how to get the 'Check Bulb' function to work correctly on the TEMP light.



LOL... indeed.
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carbon
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Report this Post09-03-2013 03:25 PM Click Here to See the Profile for carbonSend a Private Message to carbonEdit/Delete MessageReply w/QuoteDirect Link to This Post

carbon

4767 posts
Member since Apr 2004
Stupid double post...

[This message has been edited by carbon (edited 09-04-2013).]

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thesameguy
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Report this Post09-03-2013 03:47 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
My understanding from talking to an electrical engineer friend of mine is that fusible links are/were cost-effective solutions to a rare problem in a time where additional engineering or materials cost would have not yielded tangibly better results. There is no magic in a fusible link - it's just a specific type of fuse - slow blow and not quick blow, to handle random but acceptable load spikes. There's been some development since 1984, and you can achieve the exact same result with a Maxi Fuse or Mega Fuse, which is what you'll find in a modern car doing the same job as the fusible link in most <'90s cars.

If you want to replace a fusible link look up Dorman's line of bulk fusible link. If you want a modern solution, buy a Maxi or Mega fuse and holder from waytekwire.com (or wherever) in the appropriate amperage. I'm guessing, but don't know, that the Fiero expects an 80a fuse there, which was typical on '80s cars. That's probably Maxi fuse territory - I think the Megas don't come on til 100a or 125a.
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jhgraham
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Report this Post09-03-2013 06:43 PM Click Here to See the Profile for jhgrahamClick Here to visit jhgraham's HomePageClick Here to Email jhgrahamSend a Private Message to jhgrahamEdit/Delete MessageReply w/QuoteDirect Link to This Post
NAPA BELDEN Catalog 25524

Fusible Link Wire FAQ (pg 29)

What's the CONDUCTOR made out of in a fusible link wire?

The conductor in a fusible link wire is the same as regular primary wire
(copper). IT IS NOT A LOW-MELTING-POINT COPPER CONDUCTOR.
It IS approximately four wire gauge sizes smaller than the circuit wire
leading up to it. Example: a 12 gauge circuit wire would normally require
a 16 gauge fusible link wire.

How do I know what GAUGE SIZE and LENGTH fusible link wire to use?

{First it says 'Use the same size/length as the OEM did'} Usually,
a fusible link wire will be approximately 9 inches or less and is four wire
gauge sizes smaller than the circuit wire leading to it.
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Report this Post09-03-2013 07:00 PM Click Here to See the Profile for RWDPLZClick Here to visit RWDPLZ's HomePageSend a Private Message to RWDPLZEdit/Delete MessageReply w/QuoteDirect Link to This Post
I replaced the fusible link wires in my car with a fusible link box from a second gen RX-7. Makes replacement and telling if they're bad MUCH easier. Also allowed me to add a fusible link to the charging circuit. Really helped out when links A and B blew on the side of the freeway just outside of Philly during rush hour last summer. Fixed the wiring problem, replaced the links, and drove back to Michigan without further incident.

Looks just like this one:



Had to order the terminals from Mouser, minimum order quantity of 100, still worth it.

AEES, Inc. make a line of modular fuse box with MAXI fuse inserts, if you want a new, more modern equivalent.
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jhgraham
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Report this Post09-03-2013 08:05 PM Click Here to See the Profile for jhgrahamClick Here to visit jhgraham's HomePageClick Here to Email jhgrahamSend a Private Message to jhgrahamEdit/Delete MessageReply w/QuoteDirect Link to This Post
Looks good. I think it is great when we re-engineer to obtain what we desire. We all do it. I can see you have put some time, thought, and effort to centralizing the fusible links. That is a lot of money for replacing a six cent piece of wire, but it is central. I presume you know that fusible links are only utilized in catastrophic conditions. I am a purist.

------------------
Old-timer, Classic_86SE

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thesameguy
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Report this Post09-04-2013 01:22 PM Click Here to See the Profile for thesameguyClick Here to Email thesameguySend a Private Message to thesameguyEdit/Delete MessageReply w/QuoteDirect Link to This Post
RWDPLZ, correct me if I'm wrong but those look like Maxi fuses you've got there... female Maxi (FMX) versus the more common (?) male Maxi?

Cooper Bussmann sells a little doohickey called a PFM ("power fuse module", #37701) for about $12 that uses a pair of those FMX fuses on two circuits. It's a tiny little thing with small stud terminals, super-easy to install:



I think the only potential problem with FMX fuses is they max out at 60a. No idea what the rating would be appropriate for the Fiero, just a consideration. But, I use the 37701 on both my Ford Falcon and '67 Fleetwood as protection right off the battery. They work great, and are a cheap, small, elegant solution.

[This message has been edited by thesameguy (edited 09-04-2013).]

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