Wire hot to the touch

[Fastz06]

Guys,
I was working under the dash and touched the 10 Ga yellow wire that runs from the alternator to the ammeter and it was too hot to touch. Smells too.

Does this mean the ammeter is going? I'm afraid to drive it like this...
Can I test the resistance of the ammeter?

Thanks

[tcrist]

Does it only do this after running or with the key off and not has been running? If it is only like this after running then you need to check it out at your leisure (don't drive it of course). If it is just sitting there and has not been driven but the wire is hot to the touch, unhook your battery and get someone to look at it.

I would not be sure but it sounds to me like the alternator is putting out too much power to the gauge. Bad alternator maybe? As you say the wire is coming from your alternator then my guess is that you have an internal regulator and that might be bad. I am no professional by any means. I am sure someone else here can help better than I.

Terry

[patrickt]

Originally Posted by Fastz06

Can I test the resistance of the ammeter?

That won't tell you what you want to know. I'm going to assume that your ammeter is not reading +100 the whole time you're running. If you were to put an ohm meter across your ammeter the resistance is going to be zero even if it is acting "like a skinny little wire" when really it should be "a reasonably fat wire." If you were to test it, you would need to put a measured load (watts) in a circuit along with the ammeter and your measured voltage. That's a PITA. What I would do is check the connections on your wire and, assuming you don't find anything loose or wiggly, put a ten gauge jumper wire securely across the terminals of your ammeter -- that will effectively negate your ammeter. If your wire heating problems then disappear, replace your ammeter. Make sense?

[Blas]

A loose connection can cause heating in the wire too, so check both ends of the wire and the crimps. But as was mentioned, your voltage regulator may be the problem. Easy enough to test, just get you volt meter out and start the car, and check the output. Should be 13.8 to 14.2 volts...How's the fluid level on your battery. Many times, overcharging with boil out the battery liquid, and you get an acid smell too... Correct this before driving or you could be rewiring melted wires all over the car...

[vettestr]

What is the gauge showing the charge or discharge rate is? I ask out of curiosity as the wire and gauge should not be hot if 10 or 60 amps are displayed but a 60 amp discharge may be a clue to a major discharge or load downstream.

With the key on but engine not running the gauge display should be about zero. Check to see if wire heats up with key in on position but not running. Note display and if anything is running or not running that should be. Removing a fuse from items like fuel pump should stop remove discharge showing on the gauge.

[PANAVIA]

Could be just tooo muuuch stuff -- Fans and lights can add a lot of load, not to mention MSD boxes. --

[Fastz06]

Thanks for the ideas guys
I disconnected the battery until I can check it out.

[RICK LAKE]

Fastz06 you have a message

[Joe Wicked]

A hot wire has too much current going through it for it's size. This can be caused by having too much powered by the system (overloading), or by a bad component loading to ground. Bypassing the Amp gauge will tell you if it is the gauge, but I would think that it would be something else down the line. I had a similar problem on a 460. Turned out the Starter Solenoid was getting stuck. This created a huge load on the system and was burning up the wire. I shut off the truck and smelled something burning opened the hood and found the same wire you have getting hot on fire.

If you have a good multimeter, you can disconnect the Ammeter and use the Ammeter function of the multimeter to see if it is reading correctly. Be careful though as if it is from overloading you can damage the meter if you don't have the settings right.

[CHANMADD]

This is the reason that manufacturers stopped using an ammeter and went to using a Volt Meter. I had a car catch on fire once because of an ammeter.
John

[Ronbo]

Pick up a current indicator off ebay or NAPA. These lay across the wire and show you how much current the alt. is generating (load matching). I have a set of these from Snap-on, don't waste money on the digital ones that may or may not work three years from now when you need to check it again. My Snap-on's have always worked when I needed them over the past 20yrs unlike the 6 DVMs I've been through. (My Simpson 260M still works like a charm as well)

How big is your alternator? 10ga is not big enough for anything above 60A.

Although the voltmeter is more critical with today's electronic stuff like ignitions it doesn't really replace the amp meter. (ideally you'd want both in my view)

[Joe Wicked]

Originally Posted by Ronbo

How big is your alternator? 10ga is not big enough for anything above 60A.

Very good point that I did not mention. Goes to the overloading category, but you don't always have to have too much pulling current. You could be producing too much for the wire.

[kobrabytes]

Your wire is to small:

http://www.cerrowire.com/default.aspx?id=46
http://www.powerstream.com/Wire_Size.htm

I run a #8 from my alternator, although #6 would run cooler.

[patrickt]

Originally Posted by kobrabytes

Your wire is to small:

http://www.cerrowire.com/default.aspx?id=46
http://www.powerstream.com/Wire_Size.htm

I run a #8 from my alternator, although #6 would run cooler.

But those numbers are for steady current. My amp gauge, like most of our cars, shows its highest current right after starting the car while it's charging the battery -- and even then it's under 20 amps and only for a relatively short while. If your amp gauge is reading consistently over 5 amps all the time then you have a problem. The amperage running through the charging wire is usually very low almost all the time.

Afterthought -- The hghest amperage might be hit though when the fans are still running after the engine has been turned off.

[kobrabytes]

Originally Posted by patrickt

But those numbers are for steady current. My amp gauge, like most of our cars, shows its highest current right after starting the car while it's charging the battery -- and even then it's under 20 amps and only for a relatively short while. If your amp gauge is reading consistently over 5 amps all the time then you have a problem. The amperage running through the charging wire is usually very low almost all the time.

Afterthought -- The hghest amperage might be hit though when the fans are still running after the engine has been turned off.

Trust me, you are drawing too much power, otherwise the wire would be cooler. When the car is running your alternator is supplying the power. Fan, fuel pump, ignition, lights, etc. I've been through this...

Do you know for certain how your amp gauge is wired? It sounds like it is only wired between the battery and alternator, NOT showing the running load.

If you have a good schematic, send it to me.

len

[patrickt]

Originally Posted by kobrabytes

If you have a good schematic, send it to me.

len

He definitely has a problem on that wire, and it could be a faulty amp guage, or maybe even a partially grounded amp gauge, or a partial short on the wire on the alternator side of the circuit so the current is not running through the ammeter.

[kobrabytes]

Love people who can produce a schematic!

The amp meter ONLY measures charging current in this schematic, and NOT the output of the alternator to the accessories. It will however measure the draw from the battery to the accessories when the car is NOT running.

Disconnect the R and N wires from your amp meter and use an ohm meter to see if you somehow have a grounded meter. (Gnd to + and Gnd to -)

Use an amp meter to check your accessory draw. Do it one at a time. You'll probably blow the fuse in your amp meter when you check the fans unless your meter is good for more than 20 amps. With the engine not running disconnect the positive lead on the battery and put the meter between the battery terminal and the cable. (Ignition switch on run)

Before you turn on the ignition switch is there any draw?

If you use an MSD multiply your reading by 6. THe AL's draw 1 amp per k of RPM

How large is wire N? Amp gauge to battery?

Does O (alternator wire have a fusable link in the case of a short?

[patrickt]

Originally Posted by kobrabytes

Love people who can produce a schematic!

Disconnect the R and N wires from your amp meter and use an ohm meter to see if you somehow have a grounded meter. (Gnd to + and Gnd to -)

Use an amp meter to check your accessory draw. Do it one at a time. You'll probably blow the fuse in your amp meter when you check the fans unless your meter is good for more than 20 amps. With the engine not running disconnect the positive lead on the battery and put the meter between the battery terminal and the cable. (Ignition switch on run)

Before you turn on the ignition switch is there any draw?

If you use an MSD multiply your reading by 6. THe AL's draw 1 amp per k of RPM

How large is wire N? Amp gauge to battery?

Does O (alternator wire have a fusable link in the case of a short?

Kobrabytes -- there's some confusion here. He doesn't have an ERA, so that schematic doesn't apply (that's my schematic, and remember I don't have a problem, well not an electrical one that is.)

[kobrabytes]

Lol...

Trace it out... Take two aspirin, email me in the morning...

[patrickt]

Originally Posted by kobrabytes

Lol...

Trace it out... Take two aspirin, email me in the morning...

I find this thread interesting, and I hope Fastz06 gives us an update, because 30+ years ago I had an amp gauge go bad and it heated up the wire and eventually smoked it. Now granted I've owned a lot of cars with amp gauges, and that has only happened once. I can't remember whether the amp gauge gave any warning (like showing a goofy reading or something) before it finally burned up the wire.