The Stovebolt Site Forums The Shop Area The Electrical Bay An idiot with a smoking problem

Let me start by saying I don't know much about electricity, so any answer you're kind enough to provide must be at the third grade level...or lower.

Here's the situation. I put a wiring harness in my '48 3100 with a six volt system. The instructions were, well, less than adequate (16 lines on a sheet of paper), and although I thought I got everything on right, I don't believe the wire from the starter to the ammeter should be making that much smoke.

My father and I (mostly him) got the thing running for the first time since I tore it down 17 years ago, and all went well until we shut it down. The key was left in the "on" position, and a few minutes later there was smoke in the cab. The wire from the starter to the ammeter was hot. This CAN'T be normal, can it?

What did I do wrong?

No it isn't. This a a problem with some wiring vendors. They assume everyone is a mechanic. I'm afraid I can't be of much help but cletis or red58 can probably help you with this one. For a wiring harness vendor with an excellent product and customer service I recommend "YNZs Yesterdays Parts". Not only do you get a copy of an OEM wiring diagram but you also get step-by-step instructions with clearly marked wires. You also get personal telephone assistance if you need it from someone that knows their stuff. Good Luck.

This may help.

Tom R,

I think the only item "switched" with the key, that would draw battery current through the ammeter would be the ignition. If the points were closed, and the key left on, the coil would continue to pass current to ground and heat up.

I thought the wire from battery to ammeter was pretty large, gauge wise. For this to smoke, it would seem that anything smaller would have fried.

Have you tried to start the rig after this problem, and did it start? Are you sure it was only a "key left on" problem?

Normally this scenario results in cooked points and/or a burned out coil.

Stuart

Well Tom, Sounds like you let the smoke out the wire. Never let the smoke out of the wire. In order to cause enough resistence to cause the ampmeter wire to get that hot, you have something grounded. But let me ask 3 things. Do you have a cigar lighter? Is it stuck in?.
Is your truck negative ground or positive ground? Could it be that it is negative ground and you have the battery hooked wrong?

Wow, quick responses!

To answer the questions posed:

No, we hasven't started it since. You should know, however, that my old man hooked a switch up to the coil, thus bypassing the key switch, so we never went through the switch to start it. This is a standard household light switch, which we turned "on" for current, and then off when we were trying something else to get it to run ( we had carb problems, timing problems, etc.)

No cigar lighter. (Close, but no cigar....)

It's a negative ground, and the battery is hooked up correctly.

The instructions with the wiring harness said the wire from the starter to the ammeter goes on the passenger side of the ammeter. "Passenger Side" is real technical, ain't it?

I also had a few wires where the numbers fell off, but I'm pretty sure I got the right wires to the right place. (Sure I did...)

Also, when we hooked up the ignition switch with the key in the on position, there was some sparking at the battery terminal. I know something's fouled up, but I haven't a clue as to what (besides me, that is).

Not ALL then smoke is out of the wire. I'm pretty certain there's a lot more where that came from.

After I replaced my generator with an alternator, I got it running but took it to a shop where they rewired everything, removing my old regulator, for thirty bucks. It was well worth it. I suggest taking it to an auto electric shop. I doubt that you will get out as cheaply as I did but it will be done right.

That wire should be 10 ga. minimum. For it to smoke, something has to be shorted directly to ground. Is the wire touching metal anywhere? Perhaps the terminal is bent at the gauge and shorting there? If not it's likely some other smaller wires burned in the process. You need to check everything thoroughly.

Yes, the wire is quite hefty. At least 10 ga.

Is it possible there are some insulators that should be on the ammeter terminals that are missing? The gauges have been out of the truck for a long time, and could have been misplaced. Or, are there insulators between the gauge cluster and the dash I've left off? something simple like that (he hopes in vain)?

Also, is it normal for this to happen just by leaving the ignition switch in the "on" position? This doesn't seem likely, but I have to ask.

Tom R,

The pregnant question still remains...was all well and good UNTIL you turned the key switch on. This is telling you that whatever caused your mini-holocaust was on the other (switched) side of the key.

The smaller the wire gauge, the lower the ampacity rating. A 10 gauge wire would never burn up before a 14 gauge wire in the same circuit unless there was a direct short to ground somewhere in that 10 gauge wire.


Stuart

atomarc, there was no problem (that I'm aware of) until the switch was left on. At least there was no smoke. The 10 ga. wire between the starter and ammeter didn't really burn, but it was very warm, and there was enough smoke to cloud up the glass on the gauge cluster until a few minutes after the battery cable was pulled. What actually burned, I don't know yet. After running the engine for about ten minutes, things were pretty warm, and after a long day in the 90 degree heat, I had had enough truck for the day, and I haven't been back to it yet to give it a closer look.

This truck is in the construction phase, and many of the wires aren't even hooked up yet, like the gas gauge to tank wire, the headlights, tail lights, dome light, heater, radio, etc. My father said the regulator was warm, too. but I'm not so sure. It didn't feel all that warm to me.

As of now, it's just the cab on the frame. I'm trying to work out either way from the firewall.

I'm using a poorly documented, but new, wiring harness I bought a long time ago, so if there's a short, it's not from a frayed wire covering. It's from me hooking something up wrong.

Tom R,

The wire from the Batt terminal of the regulator to the ammeter, though the meter, then to the battery is the main conduit for charging the battery and feeding the system with battery voltage.

If your battery had a marginal charge in it from the beginning, as the truck ran and the system pumped a heavy charge, the regulator might warm up, as well as the wires on the ammeter.

Warm and smoking are two different things. Could the gauge cluster have gotten moisture or bugs in it from sitting for years. The guts of this gauge have to pass all current.

With dangling wires and house light switches, troubleshooting the system might be questionable at best.

Did anyone notice what the ammeter was indicating when this happened. This little gauge will give you some basic info on the system health.

You need to get back to square one. Tape up stuff that isn't being addressed right now. Take one area at a time, verify it and scratch it off your list. If the ignition system is working and the truck starts, mark that off. Move onto the charging system. It must be a logical progression or you will end up going in circles.

Stuart

It's a brand new battery.

I didn't notice what the ammeter registered, if anything. The prime concern at the time was preventing a fire.

There definitely was smoke. It fogged up the gauge cluster until the vacuum from the wires sucked the smoke back into themselves.

I refaced the gauges a few years ago and put them in plastic bags. They shouldn't be the problem.

What do you mean by taking one area at a time and verifying it?

I don't know if the ignition system is working. We bypassed it.

Could I have the switch wired wrong? There were no directions as to which wire went where on the switch, and I checked some topics here and the consensus was that there's no particular terminal on the switch for each wire. I have the "hot" wire on the middle (lowest) terminal and other things on the other two.

Tom R,

Without trying to offend you, I will say, at the very least, you need to find a wiring diagram for your truck and study it well.

Do you have a friend that has done automotive wiring? Get him to help you.

Every connection in the wiring has to be correct. If it isn't correct, it is wrong, and it won't work. You need a map to show you the right way to do it.

Get a multi-meter, a wiring diagram and someone to help you. Study all the wires and switches and fuses and gauges. Do ONE wire at a time. After awhile, all the wires will be gone and you will be done!

Stuart

Haven't read the whole string in detail, but you mentioned that you hooked up a household light switch to act as an ignition switch. I would look towards that as your problem. Could you have set it down on metal somewhere to where the terminals are touching grounded metal? Could you have possibly hooked something to the ground terminal? If so the entire metal case touching metal would ground out the circuit. I would try to ditch that switch and even just twist the wires together to see if you have the same problem. Just a thought.

Thanks, but the switch wasn't the problem. It was sitting on the heater hoses.

Although I told myself to take a day off from the truck, I just walked by it and had to take a quick peek. The facing of the fuel gauge was toasted. Now, I had connected up the "correct" wire to one side of the gauge, but didn't install the wire to the sendign unit on the tank. Could this have caused the problem? also, one of the thin black wires (for dash lights) back behind the gauge cluster had a chunk of char on it. I didn't go any further.

Tom R,

Again, I am not trying to be demeaning, but this is exactly what you are up against! It has gone from a smoking 10 gauge wire to a toasted fuel gauge to a small charred wire.

Unless you fall back and regroup, I am afraid you will be chasing your tail. Take a few days off, get a good wiring diagram and follow each wire to it proper location.

If you don't know where you are, how can you get to where you want to be. Good luck.

Stuart

Tom R,
When I rewired my gmc there wasn't very good instructions with the painless kit I got. It took alot of fuses and takin apart and puttin together. Be persistant and it should eventually turn up something real easy to fix. To me it sounds like you got mixed wires or just a short. Good luck.

Tom R,

Joker posted this diagram the other day and it's beautiful. Several of the items might be slightly different...it has 12 volts lamps in the lights.

If you study this, you will get a real feel of where things go, and why. WOW, a positive post instead of doom and gloom.

If you hold your cursor in the lower right hand corner, you can expand the print to full size.

Although the charging system and ignition systems aren't shown complete, the main idea is there...it just needs to be fine tuned!

Stuart

http://www.directcon.net/gmc248/ADwire11x17.jpg

Regarding that wiring diagram...wouldn't I have to take apart the bundle to trace all the wires? They're all neatly wrapped in electrical tape, and I don't really want to cut it open if I can avoid it. Are you saying the manufacturer may have screwed it up?

I think it's possible. For example (I'm making up the numbers and wire colors, but the point remains), the instructions say to connect wire #8 a certain post on the light switch. The wire is brown. Then further down in the instructions, You're to connect wire number 8 to a certain point on the distributor. However, this wire number 8 is blue. Now, I'm pretty sure the wire doesn't change colors somewhere inside that bundle. Perhaps you can see my confusion?

Tom R,

I can see your frustration. Clear manufacturers instructions would be the very best thing to have.

If you don't have them, all is not lost by any means. The harness will fit through the firewall and under the dash in a semi-natural fashion. Wire terminations will be close to where they attach. This is what you paid for...someone to lay it out properly.

If you have install instructions, read them carefully. The company that made this item sure wouldn't sell many if he swapped colors and numbers at random.

If you have a good wiring diagram...sort of like the one I linked, you can see where a particular wire goes. As you look at the harness, and read whatever instructions you have, it will start to make sense.

An ohmmeter (sp) is invaluable in identifying two ends of the same wire in a loom if any question exists.

Can you see what I am talking about. If you aren't familiar with wiring it really helps to see the map of the wires.

Example:

One wire will run from the RUN terminal of the key switch to the coil. You can see it in the diagram. Find it in the harness. One end will be in the engine compartment and its length will put it near the coil...the other end will be under the dash in a group of several wires near where the key switch is located. It's a puzzle, you can read the map and solve it.

Use your meter and ID the terminals on the key switch. They each do something different. You have to know what they do to be able to hook the proper wire to them. Stick little pieces of masking tape to your wires to tell you what they are and where they go.

This all sounds silly, but this is how you have to do it if you aren't Al Einstein.

Don't cut any loom open..use the ohm function to find continuity.

Sit down with a beer or a glass of fine wine (California) in a Waterford crystal glass and study whatever plans came with the harness. Keep a wiring diagram close at hand!

Sorry for the novel, I know you are frustrated, I also know with the right frame of mind you can do this easily.


Stuart

An ohmmeter? I could hurt myself with something like that! Another dumb question. Wouldn't I have to pull the wires off to get the ends near enough to reach the probes, or can one use a piece of wire as a kind of extension cord for the probes?

Thanks for the encouragment. I like my beer in a sturdy stein, though. That Waterford crystal stuff is mighty expensive, and while I'm from Waterford, it ain't THAT Waterford.

As for the key switch, how would I identify which one does what? There are no markings on it, and the wiring instructions are very clear as to where to attach the wires. I quote, "18. Key switch, spliced off of wire 17." (What splice? It must be inside the loom.) "19. Key switch to fuel gauge," (Hmmm..could this be the source of the heat?) and finally, "22. Key switch to coil." Note that none of these say to which terminal on the switch.

The numbers are the numbers on little tags on the wires. Well at least on those that hadn't fallen off...but I'm pretty sure I identified those without numbers by where they wound up and by process of elimination. It actually WAS like a puzzle, and it eventually became clear where everything went...until the smoke led me to believe otherwise.

I'd better get a lot more beer.

Tom R,

The meter I refer to is generally called a VoltOhmMeter...VOM meter. It will read all those values. Some have a "buzzer" feature so when you touch each end to something that has continuity, it will make a noise...you can keep your eye on the work and listen for the buzz.

The key switch is sometimes marked. The center post is usually power and each post around the perimeter would be Accessory--Start--Run. Your truck might not have all these features. Again, this could be figured out with the ohmmeter.

You stick one lead on the center post and the other on one of the posts around the outside. When you turn the key, the meter will buzz when there is a circuit between the leads...continuity! You know that start/run is all the way turned..find the buzz. You know that accessory ISN'T start/run, but another key position...find the buzz.

This is all done with the device disconnected from the wires. If you need to identify a wire that goes from under the dash to the back of the truck for instance, you ground the wire at the back of the truck, attach a meter lead to ground near the dash and start touching wires with the other lead...when you get to the wire you were hunting for..bingo, the meter will buzz!

You really don't have to have numbers on wires, or colors for that matter. It makes it much easier, but with a meter and common sense you can work around it.

Wire size is important. Certain circuits carry charging loads, or horn loads or lighting loads. This is where the manufacturer hopefully did his homework.

I am sure you get the idea. Think of it as a jigsaw puzzle. As you run the wire from the starter to the ammeter, put a little X on this wire in the diagram...all taken care of! When every wired is crossed off...make a run to the liquor store for some Night Train Express!

Again, I am sorry for the novel, but if you ask, I will try and answer.

Stuart

Just one caution to information Stuart has imparted: disconnect the battery before using the VOM on the Ohms scale for continuity tests.

All the feedback you have gotten so far is good stuff. My addition to the comments is probably not as useful, but I have had the same problem (which doesn't mean the cause is the same). My cause was that the speedometer cable (which is metal shielded) made contact with one of the terminals on the ammeter causing a short. Unknowingly I had shifted the routing of the cable while doing some work underneath the dash. I know this is "off the wall," but check the speedometer cable for burn marks. Since you are looking at a variety of things, I thought I would just add my experience on what turned out to be an annoying but simple problem.

I think part of your problem is the harness not being color coded and the ID numbers falling off. What brand is it so others can avoid this problem?

I bought a harness from Hotrod wires. This harness is color coded using the same code as late model GM wiring. This is a universal harness and is not a direct replacement for a truck harness but I had little problem putting it in my '56. What questions I did have were quickly answered by the mfgr.

cletis, the manufaturer is long out of business. I bought it over ten years ago. It's specifically designed for the truck, however.

hey I've got a silly question I have a 49 chevy 3100 is that a positive ground truck or negitive grounded. I'd like to get a battery in it to see if it works and runs. It would improve my marital relations

Negative.

Ut sounds like your wirirng harness isn't color coded so it might take you some extra work to figure everything out. If you don't unbundle your wires, you'll have to figure out which wire of the right length goes between the two places you need to hook it up. you could do that with a test light, a wire and an aligator clip. Put the harness through the firewall. Clip the accessory end of the wire to a hot lead from the battery. Go inside the truck, ground your test light and start touching the various candiates for the right wire, the one that lights up will be the right one!

Sounds like you smoked your fuel guage or your sending unit, or both. If either one was 6v its toast.

If the engine turns freely, and your generator is okay, provisionally wiring it to run shouldn't be hard.

Check the line from the generator/Alternator to the ammeter to the battery/starter post.

Check the line from the starter post to the ignition switch.

Check the line from the ignition switch to the coil.

Check your grounds (bat-frame, engine-frame, frame-body)

The ingnition switch on my truck has three posts. One is hot in from the battery and the other two are hot when the key is turned. It's easy to figure out which is which with a VOM. Just figure out which one doesn't flow when the switch is off and hook your hot lead to that one.

thanks

Well, I'm still not sure what happened, but I am sure of one thing - I need a new harness. I got under the dash yesterday and found a lot of melted plastic. Both wires from the ignition switch were fried, and the gas gauge was welded to my brand new heat gauge. I'm guessing they were touching, and the gas gauge used the heat gauge for a ground and the truck turned itself into a toaster of sorts. Anyway, a major part of the harness is a plastic and copper souffle, so I ripped the whole thing out and I'll buy a decent harness with good instructions and start over.

What amazes me is that it took days to put the thing in, but only about ten minutes to rip it all out.

The fuel gauge may be okay with a new decal, but I'm leaning toward replacing it anyway. The sending unit is okay because I didn't have the wiring back that far yet, so it wasn't invited to the cookout.

Could the simple thing of the two gauges touching have caused this mess? Could there have been a missing insulator between the fuel gauge and the gauge cluster housing? I notice there appears to be insulators under the other gauges, but not the fuel gauge.

Where's the best place to get a good harness with idiot-proof instructions?

good question, I just bought an EZwire kit went 21 fuses becasue I figured somewhere down the line I would need more as I convert the 53. After reading this string, Iam afraid to start! The truck runs fine now but I am changing out the guages (which don't work)and organize the wiring instead of the 3 fuse stations that were rigged up over the past 25 years. I was planning to simply run new wiring where the old wires ran but now I am nervous, is EZ wire kit any good for beginers like me?

Alan's truck is a lot more modified than mine. I'm trying to be fairly original with mine. It's still 6 volt, has the original 216, etc.

I just ordered a YNZ harness and a new gas gauge. The harness has a braided covering like the original. If I burn that up, read my obituary in the Albany, NY, Times Union.