Toasted my fusible link last night!

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Weak440

Weak440

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I have been battling a head light issue for quite some time. This showed up after I bypassed my ammeter in the dash with a 10ga wire and a fuseable link from the output on my alternator to my starter relay.

At idle the lights are fine but, just up off of idle they (for lack of a better term) strobe. Both, high and low beams. The strobeing pattern speeds up with the engine rpm. It has been driving me nuts. The first thing I changed was my voltage regulator and it made no difference.

I swapped alternators and made sure that the alternator case was grounded. That made no difference.

I cleaned and checked all of my grounds in the wiring harness under the hood and still no effect.

I ended up adding a set of relays to my headlights and that made them brighter but, did nothing for the strobing. I ended up swapping my dimmer switch and my headlight switch in my cluster. Neither made any difference.

So, out of frustration last night I picked up another voltage regulator and starter relay. When I got home (in the dark) I swapped the voltage regulator and the starter relay. I should have changed one thing at a time but, I was frustrated and hate working in the dark. I decided that I should go ahead and upgrade the bypass wire from the back of my alternator to my starter relay to an 8ga wire with a fuseable link.

I had everything wired up and was getting ready to fire it up. I popped the trunk to hook up my battery and it sparked quite a bit more than normal. I thought ohhh no, I stood up and could see smoke starting to come up from under the hood.

CRAP!

I quickly disconnected the battery and rushed up there expecting to see the worst. I instantly started feeling up all the wires I could get my hands on and turns out the only thing that was hot/smoking was the original fusible link at the bulk head.

I felt pretty stupid, :banghead: I am not sure what happened. I double checked everything that I could and didn't see anything that would have caused that to happen. Yes, my battery was connected correctly!

As I was laying in bed :banghead: I started to wonder if when I tightened the nut down on the stud on the starter relay if maybe I bent one of the terminals and it was making contact with the case of the starter relay and shorted it out? Or maybe the terminal on the back of the alternator was touching the alternator case?

I had to close it up and walk away from it last night. It kind of made me sick that I made such a stupid mistake.

Anyone have any thoughts? I am going to replace the fusible link tonight and go over everything I touched with a fine tooth come before I touch the battery again. #-o
 
No need to, "smoke" happens

The way to troubleshoot a bad or dangerous short is to figure a way to protect the system so nothing can be damage, and this is actually fairly easy.

What you need is "a lamp."

Disconnect the battery ground, and put your lamp in SERIES from the battery NEG post to the disconnected ground clamp. This makes a current limiting device. When you get all loads safely "off" and any shorts removed, the light will go out, and you can short just about anything, and all that will happen is, that the lamp will light up

"Things that are handy."

Sometimes a 12V test lamp is not heavy enough wattage for this, as it lights with fairly small current. I use an old headlight, and an old stop / tail light

A stop tail can be wired a number of different ways to increase or decrease the current "it takes."

1...Very low current. Leave the shell of the lamp unconnected, and use the stop wire for one terminal, and the tail wire for the other. This creates a lighter wattage 24V bulb that doesn't draw much current

2....A little more.....Use the lamp shell as one terminal, and the tail wire.

3....A fair amount more wattage..........use the lamp shell and the stop wire

4....Max wattage.......Use the lamp shell for one terminal, and twist the stop and tail wires together using both of them as one terminal.

==========================

Just hook up your test lamp. If it lights, go round and insure that everything is off. Don't forget dome, trunk, glove box lights, and the key off.

If it still lights, unconnect "stuff" one at a time, starting with "what it is that you messed with."

(Might even be a defective starter relay)................."New" does not mean "functional."
 
Thanks for the help 67Dart273!

I wanted to see what the damage was do, I pulled the bulkhead apart last night. Looks like I have some rewiring to do.
 

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Damn. You don't want to hear this, I would untape the harness and inspect it. Typical for conductors to melt insulation and fuse together.

In the early 70s not long after I bought my favorite car

81sruds.jpg


Some girls in a Datsun "aholed" it as I was stopped in traffic. "They didn't see it!!!"

Anyhow the dealer, McCune Chrysler Plymouth in National City who hosed it up permanently, "gave" me a clapped out loaner car, a slant Valiant. Bald tires, no brakes, it was 'quite a deal'

One cold morning in San Diego (Miramar) I had started it up, going to get off work. My Chief came in and gave me the Columbo act. "Say, is that loaner supposed to be squealing and smoking and making noise?"

The alternator had stopped and the belt was squealing and slipping. I shut it off, for no good reason loosened up the alternator and wiggled it with a rag AND IT SHORTED INTERNALLY as it turned out a diode had fallen inside the unit!!!!!

So I stood there and watched, as the harness went fzzzzssssssiiiiii......z.z.zzzzzzzzzzzzppphhhhhffffssszzzzzzzsssssssiiiiitttttttt ..........ssssiiiiitt!!! AND THEN BLEW THE FUSE LINK!!!!!

So I called the Dealer. And told them to send a wrecker. And bring out another loaner. And they sent the wetback with a jumper battery in his trunk......And he looked under the hood......And he looked at me......And he said "This thing is all burned up.........We are gonna need a wrecker!!!!"
 
Oh man that sounds like it sucked!

I ordered a replacement bulk head that had the fusible link in it. Since the weather is dropping off to crap soon I am planning on pulling the wiring harness out and doing exactly what you said. I am going to repair any damage I find and probably tape the new 8ga bypass wire in to the old harness to try and hide it a little better.

I was considering drilling the bulkhead in the firewall where the two terminals for the ammeter and running new 10ga straight threw the bulk head and up to the back of the dash.

I still need to pull the gauge cluster out and look for damage in that wiring harness as well :banghead:
 
Weak440 said:
How did you end up fixing yours?
Click to expand...

Actually it was pretty easy...new Packard connector and a new fuse able wire...there was a bunch of postings concerning this when I fried my wire while installing a new instrument cluster...I think you can do a search and write in fuse able link and the postings are all there...good luck...I know I spent 3 sleepless nights worrying about if I was ever going to get this fixed...Marla
 
done that one time ended up buying a fusible link with the kind that take the 30amp fuse chips.work just fine afterwards.
 
bbmopars said:
done that one time ended up buying a fusible link with the kind that take the 30amp fuse chips.work just fine afterwards.
Click to expand...

That's how my car was when I bought it, so I pulled it out and replaced it with a self resetting circuit breaker.
It will trip with a short and then come back on in a few seconds, but with a constant dead short it sounds sort of like a signal flasher. :D

I have never had it happen on my car, but I have on others before they could get the battery disconnected.
Never burns anything up though because it just shuts off if the short is still there.
 
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