Amp Gauge Blow Up

[bliss]

Originally Posted by patrickt

Do you see how the left side of fuses #1 and #2 are joined together? Do you see the yellow and red wire both are soldered together on to the top screw to fuse #1? Yellow goes to the ignition switch and RED goes to the amp gauge (orange goes to the alternator). The red wire is what you want to snip along with the top lead to the circuit breaker. That red wire is fried up under the dash. This is really an easy fix, much easier than you think. And a voltmeter is just a simple two wire run.

Here's my fuse block set-up - as you can see, very old and a little scary looking to me. Notice that there isn't a fuse on the left side, first slot. The Cobra ran fine with no fuse in that slot - everything seemed to look OK.

[patrickt]

That "empty" fuse usually runs the fan. Your fan must be wired in and fused elsewhere. But look over on the left side and you can see that the hot sides of fuse one and fuse two are connected. That's the charging path. All THREE of those labeled wires are connected together. It also kind of looks like the connector between fuse one and fuse two looks a little melted, but maybe not. The red wire is the one that should run to your ammeter and from your ammeter to the circuit breaker, that is the last stop before the battery. The other two wires I have labeled for you. Now, I could always be wrong on this so check the actual wiring. You can look under the dash at the ignition switch pretty easily, and of course look at the alternator. You can replace that red wire that caused all the problems without having to actually remove it. Just cut it at both ends (fuse box and circuit breaker) and cut it out from under the dash as best you can, then tape it all off. When you drop the dash you'll be able see how that red wire goes to the ammeter. When it heated up, it may have damaged some other wires as well, but you'll be able to see that. If it looks really, really bad to you, then just send it up to ERA and they'll do it for you. But I think that if you replace that red wire, with a straight shot between the circuit breaker and fuse box, and then touch up any scorched wires under the dash, and put in a volt meter, you'll be fine.

[patrickt]

You can see why the prior owner pulled the fan fuse and, I'm guessing, ran a direct fused connection directly to the fan. There is evidence of heat damage from the fuse blowing, probably more than once, and he kept upping the amperage and it kept blowing. What is that little black necklace looking thing? Is it some kind of insulation buffer? And is the apparent melting on the connector between fuse 1 and fuse 2 just an optical illusion? I've never seen that guy even pucker before, much less melt. I'm guessing it's just a trick of the camera.

[bliss]

Originally Posted by patrickt

You can see why the prior owner pulled the fan fuse and, I'm guessing, ran a direct fused connection directly to the fan. There is evidence of heat damage from the fuse blowing, probably more than once, and he kept upping the amperage and it kept blowing. What is that little black necklace looking thing? Is it some kind of insulation buffer? And is the apparent melting on the connector between fuse 1 and fuse 2 just an optical illusion? I've never seen that guy even pucker before, much less melt. I'm guessing it's just a trick of the camera.

Black Necklace...
A closer look - it's some sort of crud that has built up on the end of the wire clip - looks a little baked on to me - probably tape, etc.

Between 1 and 2 fuse...
Looks like someone scraped something off.

I'm wondering if I should consider starting over - new harnesses, etc.

[patrickt]

Before I agreed with that, I'd like to see a couple of shots of whatever it is that's powering your fan and how the previous guy did it. That will tell you a lot.

[RICK LAKE]

Bliss you have my number, call me. Call ERA first and tell them you need a new fuse block. The rest is just time and doing 1 wire at a time. ERA will give you a wire diagram of the car with colors and gauge thickness. We do need to open up the harness and remove the clamp to see what other damage is done. SW has a black face gauge for cobras with a volt meter that goes to 16 volts. I think it is colored with red, yellow green. If you don't like the colors remove the clear cover and get black touchup paint and color over them. NO body will know but us. The reason the fuse block melted was the short was on the other side. The amp gauge terminal insolators got hard and just burn up. Beening there is not fuse from gauge to fuse block, it burnt those wires like you see. Voltage meter will fix this. If you played the game operation, this is a piece of cake, pie,beer, steak, candy.
Loosen the screw of the dash and drop the steering column. You will see how easy it is. When done just tape up the harness. What would you do if you where out in a desert, no AAA to help and no phone. You would fix the car. Play McGiuver and stop whining. this is part of owning a cobra. This How old?? That wiring has a better copper content than the new stuff. repair what you see. wrap the other wires by themselves. Rick L.

[patrickt]

Originally Posted by RICK LAKE

...fix the car. Play McGiuver and stop whining. this is part of owning a cobra.

Compared to replacing the turn signal stalk control on a Grand Prix, this is a piece of cake.

[bliss]

Originally Posted by RICK LAKE

Bliss you have my number, call me. Call ERA first and tell them you need a new fuse block. The rest is just time and doing 1 wire at a time. ERA will give you a wire diagram of the car with colors and gauge thickness. We do need to open up the harness and remove the clamp to see what other damage is done. SW has a black face gauge for cobras with a volt meter that goes to 16 volts. I think it is colored with red, yellow green. If you don't like the colors remove the clear cover and get black touchup paint and color over them. NO body will know but us. The reason the fuse block melted was the short was on the other side. The amp gauge terminal insolators got hard and just burn up. Beening there is not fuse from gauge to fuse block, it burnt those wires like you see. Voltage meter will fix this. If you played the game operation, this is a piece of cake, pie,beer, steak, candy.
Loosen the screw of the dash and drop the steering column. You will see how easy it is. When done just tape up the harness. What would you do if you where out in a desert, no AAA to help and no phone. You would fix the car. Play McGiuver and stop whining. this is part of owning a cobra. This How old?? That wiring has a better copper content than the new stuff. repair what you see. wrap the other wires by themselves. Rick L.

Unfortunately, I've lost practically all hearing so I no longer use the telephone.

Question....

1. What are the changes to the wiring, e.g. changing to a voltmeter (currently two wires go to the AMPS Gauge - with one directly from the Starter Solenoid)?

BTW - thanks so much for all your input.

[patrickt]

Originally Posted by bliss

Unfortunately, I've lost practically all hearing so I no longer use the telephone.

Question....

1. What are the changes to the wiring, e.g. changing to a voltmeter (currently two wires go to the AMPS Gauge - with one directly from the Starter Solenoid)?

BTW - thanks so much for all your input.

Unlike the ammeter, you can run a volt meter off of any switched power source (meaning it's only hot when the key is on). It draws virtually no current, so it does not have to be a beefy circuit. For instance, if you have a heater fan under there, the hot line feeding it could be easily tapped in to. If you have a cigarette lighter in the dash (that doesn't work when the key is off) that would be another nice spot to tap in to. Or you could just run a new wire out through the grommet and attach it the fused side of fuse #4, which is switched, IIRC.

[DanEC]

Is there a Smith's voltmeter that is a good match for the typical Smith gages?

Patrick - you have Smiths gages - are you using a voltmeter?

Bliss - I'm curious about when you tore into your wiring - were both connections to the amp gage tight? The wiring damage looks similar but even worse to the damage I had when the main lead at my alternator came loose backed off. I'm wondering if this might have been due to a lead coming loose.

[patrickt]

Originally Posted by DanEC

Patrick - you have Smiths gauges - are you using a voltmeter?

No. I use an ammeter. But, I have a parallel line around the ammeter. Parallel lines in a circuit divide the current based on the respective resistances of each. So, should the ammeter, over time, create more and more resistance (which would normally present a danger), more current passes through the parallel line, instead of burning up the ammeter. The readings on the ammeter are no longer spot accurate (if they ever were), but they're reasonably close and clearly show a charge or discharge condition. What most people don't realize is that, when the engine is running, and all the electric stuff is running hard, the current through the ammeter is still next to nothing. That's because the load sits on the same side as the alternator's feed -- and that's why your ammeter should be reading just a bit above zero. The only time it should show a higher plus reading is when the car has just been started, and the battery needs a little recharging. But once that's done, your ammeter should only be passing a few amps -- hardly any. Now, if your alternator isn't running, then all current is running through the ammeter. Big current motors can still draw a heavy load though when they come on -- that's why you may see your ammeter needle swing hard when your fan comes on but then settle back to zero.