You may or may not have heard, but the GreenGT didn't make it to the Dells Run this past weekend due to an electrical gremlin that I haven't encountered before. Many of you that have heard my stories (either here or in person) would jump to the alternator, or more specifically the regulator (much as I did) as being the most likely source of trouble. (for anyone unaware, my GreenGT has a history of "eating" alternators on a semi-regular basis... so much so that I carry a spare on all road trips).

Anyway ~ Friday morning we packed the car and set out for Wisconsin (est. travel time of 3.5hrs). About 35 miles into the trip the voltage drops down to about 8 volts on the factory gauge... now I hadn't exactly been watching it closely, but I hadn't previously noticed a shortage of charging (last alternator replacement/rebuild was just this past fall for a bad regulator... twice).

Assuming once again that I picked up a less-than-quality part... I continued on about 5 more miles to the Zumbrota, MN Pontiac Dealership. My wife suggested that if labor wasn't too excessive, that I might even let them do the alternator swap. The quoted me 1.7 book hours & $120 (that's a reasonable rate), but that their tech didn't come in until 1pm (it was then a little after 11am). So I decided instead to do the swap myself (with Nick/Carbon's assistance) in their parking lot. Less than an hour later I had the spare alternator in, and a test firing of the car showed no improvement in charging. So we took the first alternator to a nearby NAPA for testing ~ where he found that it was charging plenty (if not even a bit too much, being nearly 16v on the test rig). He also informed us that both wires needed to be "hot" in order for the alternator to start charging correctly... and that we might look there as a source of the problem.

Back at the car, we checked the interior fuses (all fine) as well as the dash light (on when key is in the on/run position with the engine not running).

At this point, we didn't have any electrical testing tools, or copies of the wiring diagram (thinking back, we could've probably asked the dealership... but they hardly knew what a Fi-Air-O was, and I was already tired of working on it and not getting anywhere). So Nick & his wife continued on towards Wisconsin, while my wife & I limped the car 36 of the 40 miles home (when the battery totally flatlined while in a left turn lane)... my mother-in-law picked up and delivered a replacement battery ($45 @ WalMart) to get us the last 4 miles, where we threw everything into the Outback and once again set out for Wisconsin.

Upon arriving in the Dells (this time with my Haynes Manual, but no Fiero) Nick/Carbon immediately flipped to the charging diagram and pointed out a fusible link as the likely culprit (as the dash light worked, and the alternator checked out OK at NAPA).

Now I'm back home (and commuting 20 miles per day on "battery power"... since it's my shared primary mode of transport along with motorcycle), and a brief inspection doesn't seem to tell me squat about the fusible link. I used to be under the impression that a fusible link was essentially an inline fuse... nope. I was wrong there.

So I've read through numerous archived topics I could find, as well as the Ogre's Cave topic(s) relating to the fusible links... but I still don't feel confident about what I see on the pages vs what I see in the engine bay. I did stop at NAPA and pick up a 14 gauge fusible link (it was the closest they had to the Metric 3 one Ogre listed & suggested in his article).

I haven't yet pulled the entire wire from the loom to see where it starts & stops, so can anyone shed some light on how long this fusible link should be? (the replacement I picked up from Napa is probably 8-10 inches in length with a loop on one end) I think I located it on the battery block, but it doesn't appear to be burnt or damaged upon quick inspection.

Can anyone shed some simple light on this issue, or suggest a quick & easy way to isolate the problem? Thanks!

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Looking for Fiero posters?

[This message has been edited by MinnGreenGT (edited 06-02-2008).]

Rob,

The fusible link is just a smaller piece of special wire designed to melt at a given amperage. length varies but is not too critical about 3 inches in most spots that I have seen. Most of the time the link breaks and does not actually " blow". When it blows it usually melts the outer rubber casing. When it breaks it dose not breake the rubber casing and usually will make contact and break contact intermittently. You can do the tug test to see if it is broken, by pulling on the ends of the link if broken it will stretch. Otherwise you can use a test light from one end to the other .

Thanks Tim! So... where the wire from the Alternator meets the power "block" in front of the battery tray, I can see the fusible link denoted by the plastic "block" on the wire. I assume that those plastic "blocks" are simply indicators that the segment of wire is a fusible link, and nothing more? (this is why I guess I used to assume these were actually inline fuses...).

If I'm understanding this correctly... I should be able to pull that wire from the loom and within a short distance it will have a butt-end splice to a "normal" wire? I'd just snip it there... and replace it with the new segment? (after reading the Ogre's info ~ I also picked up a small pack of weatherseal crimp butt-end connectors).

Is there any advantage to buying the fusible link in a roll form instead of the little segment with the indicator block? (other than bulk volume is cheaper?)

[This message has been edited by MinnGreenGT (edited 06-02-2008).]

Yes the big black rubber thing is just a splice. I think from there to the power block is the fuse. I may be wrong as I haven't looked at one lately. Tt might be before the splice and there is a connector to disconect too. I think I might have killed off a few brain cells this weekend tha had that info stored in them. The only advantage to the roll of fusable link wire is that you own a Fiero and will probably need more.

quote Originally posted by MinnGreenGT: I did stop at NAPA and pick up a 14 gauge fusible link

If I remember right its the 12 gauge link we need for this application. I went through this whole thought process a couple years ago; 12 gauge links seem to be completely unavailable and although mine seemed perfectly OK I wanted a new one, or at least a new one to keep as a spare (I had replaced the 8-gauge wire all the rest of the way down to my alternator, and in the process cleaned up some really nasty splices done by previous owners). I eventually wound up using my original 12 gauge link, and picked up another 12 gauge link from the junkyard to keep as a spare.

14 gauge seems to be readily available at parts stores (and the dealer) but I'd be leery of it burning up.

Tim... Brain cells? What Brain Cells? LOL!

quote Originally posted by Fiero STS: ...The only advantage to the roll of fusable link wire is that you own a Fiero and will probably need more.

It's probably amazing that in the 15 years I've been around Fieros, that I've never encountered this before!

quote Originally posted by css9450: If I remember right its the 12 gauge link we need for this application. I went through this whole thought process a couple years ago; 12 gauge links seem to be completely unavailable and although mine seemed perfectly OK I wanted a new one, or at least a new one to keep as a spare (I had replaced the 8-gauge wire all the rest of the way down to my alternator, and in the process cleaned up some really nasty splices done by previous owners). I eventually wound up using my original 12 gauge link, and picked up another 12 gauge link from the junkyard to keep as a spare. 14 gauge seems to be readily available at parts stores (and the dealer) but I'd be leery of it burning up.

Yeah... I wondered about that, but Ogre's Chart here indicates that the appropriate (but possibly inadequate) AWG replacement for a 3mm wire is a 14... I didn't specifically see a 12 "link" segment, but I forgot to check the "rolls" to see if they had it available there. If not, I live around the corner from a CarQuest distribution center... if anyone has it, they should (or my local GrayBar).

Thanks for the additional input!

Rob,

If you need any additional electrical help, just ask. Test-light the fusible link on each side, as well as disconnect your battery ground, and check for resistance across the wire from about 6 inches down from the plastic lug and the metal ring for the junction block.

Well... leave it to me to screw up what could've been a simple repair!

I wanted to be sure that it was the fusible link before removing it... so I grabbed my trusty meter and started ohming out the different locations. I wasn't getting anything at all from the alternator hot post and the hot post on the wiring block... so I was pretty sure at that point it was a bad link. I tried to check the link itself, but didn't want to cut into the line further down than necessary. So I snipped out the (assumed bad) fusible link. Oddly I still wasn't getting a closed circuit reading from the alt post to the other end of the wire. A quick check showed the link as being good (only .8 ohms)

About this same time I realized a number of other things... that the 14 gauge link I picked up was definitely too small, as was the weather proof butt-end crimp connector (Duh... it has to fit an 8 gauge wire on the other end). So I jumped in my wife's car and zipped into Apple Valley (about 8:15pm) - only to find that CarQuest had closed at 6pm, Napa at 8pm, and Checker was open until 9pm... but didn't stock anything (at all) for wiring larger than 10 gauge.

When I returned home (after thinking a little more clearly while driving) ~ I started digging deeper & pulled the wiring harness off the alternator (2-wire plug & single "hot" lead) to do a few more tests (something I should've done before cutting anything). I quickly discovered that I wasn't getting any connectivity between the ring terminal on the hot lead... and anything else. Everything else was showing .8 ohms everywhere it should.

A little closer inspection... anything look out of place?


Ahhh... the terminal is shot (and ugly). I don't recall replacing that one, but it could've been one of my early roadside fixes from a few years ago...


After all this crap, all I need is a simple single 8 gauge circular terminal... which I don't have (I've got 'em for everything from 16 up to 10 gauge, and 6 down to 2... nothing for 8 gauge). And to add to it, I now need to try and locate a more-correct fusible link (hopefully NAPA will have something), or if all else fails... reuse the original (not my ideal plan). The good news is that I'll take this opportunity to replace a decent amount of original, dry, and crumbling plastic loom!

Thanks guys for your input... hopefully it'll be a quick fix tomorrow (and a dry commute on the cycle)!

[This message has been edited by MinnGreenGT (edited 06-02-2008).]

The plastic conector has a number on it, that is the proper size of fuse link. The lenght of wire for the link is the same length that was there before. I am not positive about this one, but many of them are 6" long.

quote Originally posted by Electrathon: The plastic conector has a number on it, that is the proper size of fuse link. The lenght of wire for the link is the same length that was there before. I am not positive about this one, but many of them are 6" long.

Yup... per Ogre's info (and what's printed on the link itself) ~ it is a 3mm wire (which his conversion table shows a 14 or 12 gauge wire to be the nearest AWG replacement size... which is of course all that the local NAPA stocks!). And 6" sounds about right without going back and actually measuring the old one

quote Originally posted by MinnGreenGT: Yup... per Ogre's info (and what's printed on the link itself) ~ it is a 3mm wire (which his conversion table shows a 14 or 12 gauge wire to be the nearest AWG replacement size... which is of course all that the local NAPA stocks!). And 6" sounds about right without going back and actually measuring the old one

Yep, a 12-gauge fusible link is called for by the factory service manual ("rust" color). I wouldn't try skimping with a 14.

quote Originally posted by css9450: Yep, a 12-gauge fusible link is called for by the factory service manual ("rust" color). I wouldn't try skimping with a 14.

If you want to get technical... the "rust" link from the factory is a 3mm - a 14 is "gray" and a 12 is "light blue"

I finally got it all back together & buttoned up:

• New 8 gauge ring terminal (battery style) at the alternator hot post
  
• New 12 gauge fusible link w/ring terminal at the power block
  
• Removed & Spliced Damaged section of the red alternator "Red" wire
  
• Heat Shrunk & Sealed all butt-joints and connections
  
• New Plastic Loom over most of the harness from the alternator back to the power block
  

Fired the car up... immediately showed 13.5+ Volts (and the battery was already only running about 10 volts from my driving over the past day). Finally! Oh... and my commute today on the bike was mostly dry

Thanks again to everyone for your help!

Here are the Delphi Packard wire colors. (Guess the .35 sq mm links are not available from Packard).



Another (unknown) manufacturers colors are not the same.

quote Originally posted by spark1: Here are the Delphi Packard wire colors. (Guess the .35 sq mm links are not available from Packard). Another (unknown) manufacturers colors are not the same.

LOL - Figures... no consistency

(funny though... my 12 gauge is pretty much the same color as the 3mm in the 1st photo)

Metric and AWG fusible links are often interchanged. Heres an example from MAD Electrical:

[This message has been edited by spark1 (edited 06-04-2008).]

quote Originally posted by spark1: Metric and AWG fusible links are often interchanged. Heres an example from MAD Electrical:

Ummm... yeah... I think I mentioned the interchangeability once or twice (in reference to the article in Ogre's Cave).

Good simple & informative link. Interesting though, that they reference soldering the connection ~ when I've read quite a number of sources that suggest NOT soldering, as it can change the properties of the link itself. That being said, I noticed that when I cut the plastic "sleeve" off the factory link the other night - it was clearly soldered.