oamhmad

iTrader: (1)

Tried to start up and saw sparks at the positive battery terminal. Hooked up a multi-meter and confirmed that there is indeed a short at the terminal at all positions of the ignition key, although the resistance to ground is lowest when the key is in the run position.

I pulled out all the fuses in the under dash panel one by one. No difference.

Recent changes were new heads and cam install. I did tuck away the harness behind the motor at the firewall a little better but didn't change anything.

Car is running a holley carb and non computer controlled distributor so pretty much all the under hood connectors are unplugged. Car ran fine before the head swap. Any ideas how to find the short?

Galaxie500XL

iTrader: (1)

New heads...did you reinstall the ground strap between the head and firewall?

red rock

iTrader: (2)

Sounds like a pinched wire.

oamhmad

iTrader: (1)

Yes i did. I even installed a new ground strap from the passenger side head to one of the bolts for the windshield wiper motor mount bolts.

Regardless, I don't think a missing or weak ground would cause a short in the positive battery terminal.

QwkTrip

iTrader: (22)

Sparks happen when an electric arc jumps an air gap between two points at different voltage. The problem is exactly where the sparks are flying -- you don't have to search any further. And it is really easy to find.... just look for the burned spots.

Likely a loose connection at that point. If it truly is happening at the battery terminal then another possibility is the terminal itself is loose in the battery. A FAULTY BATTERY THAT SPARKS IS VERY DANGEROUS. If a spark forms inside the battery then it could ignite hydrogen gas and the battery blow up.

How did you determine there is a short to ground? Reason I ask is because a real short to ground with a good solid connection will smoke the wire and burn it open nearly immediately (or pop circuit protection). A really poor connection could spark.

John in RI

iTrader: (167)

oamhmad

iTrader: (1)

How did i determine a short to ground at + battery terminal?

i used a multimeter. Disconnected + batt terminal from battery. Made sure the terminal wasn't touching anything metal. Then one probe attached to the + terminal and one to a valve cover. Multimeter resistance reading immediately went to zero.

skinny z

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skinny z

You can't use a multimeter that way. Resistance testing has to be done with zero voltage present. And that's what you have if you go from the positive battery post to the grounded valve cover. You're getting a false reading.
Now if you were test continuity between the positive cable (when disconnected from the battery) and the valve cover and got a zero reading, that's a problem. Depending on the quality of the multimeter that is.

oamhmad

iTrader: (1)

Yes this is ecactly how i tested continuity and got a zero reading. This rules out a loose battery terminal as someone else mentioned. Not sure where to lo9k for a short given i saw sparks at the positive terminal itself.

skinny z

.

red rock

iTrader: (2)

This is why i said, you may have pinched some wires. Quote; [Recent changes were new heads and cam install. I did tuck away the harness behind the motor at the firewall a little better but didn't change anything] I guess i would start there. Next would be the starter and wires to it. Then the alternator and wires.

oamhmad

iTrader: (1)

Yes this is ecactly how i tested continuity and got a zero reading. This rules out a loose battery terminal as someone else mentioned. Not sure where to lo9k for a short given i saw sparks at the positive terminal itself.

red rock

iTrader: (2)

Check post #12

skinny z

[QUOTE=oamhmad;6222435 Hooked up a multi-meter and confirmed that there is indeed a short at the terminal at all positions of the ignition key, [/QUOTE]

The above reads like you tested at the + terminal on the battery and not the + battery cable.
The sparks at the connection between the battery and the cable might indicate that the connection was loose although that wouldn't be the cause of the problem.
So if your tests have been performed accurately, that is you tested from the cable to ground and saw zero resistance, I'm with a few others here that suggest you may have pinched a wire when doing the engine work. It happens all the time...

QwkTrip

iTrader: (22)

Did the screen display "0" or "OL". Ohmmeters virtually never give a 0 Ohm reading. In real life there is always resistance and rounding errors that will produce some kind of number.

red rock

iTrader: (2)

My analog Simpson meter always gives me a "0" reading. My digital will give me a "0" reading on an extremely solid short, but may vary 0 to .1 ohm on a good ground.

oamhmad

iTrader: (1)

Thanks to all who have replied..here is an update with pictures:

Quick recap: saw sparks at the + batt terminal when trying to start the car. Disconnected the + batt cable from the terminal and tested at the now disconnected + cable using a multimeter. Discovering a short to ground in all ignition key positions. Yes I made sure the cable itself was not touching any metal.

Update: Something is up with the alternator. I disconnected all its wires and tested resistance between its Positive terminal and the rest of its body. I was expecting to see a reading of 1 indicating over-range but I actually saw a reading of 5M-ohms. Not sure if this is normal.

So with the alternator now disconnected from the car I tested resistance between the + batt cable and the valve cover once again (batt cable actually disconnected from the battery). Here are the results:



Key in Off position: Resistance over range on multimeter. No more short to ground. (see first pic)

Key in Acc position: Same as Off position

Key in Run position: Multimeter immediately indicated 0.00 resistance which is a short to ground. (see second pic)

Key in Start position: same as run.

So in conclusion. I still have a short to ground although removing the alternator got rid of the short in the Key Off and ACC positions. It looks like the short is somewhere in the ignition circuit.

I did check under the valve covers and under the heads at the firewall for pinched wires. Nothing.

Did installing new heads have anything to do with this? Could be, but keep in mind I actually successfully started and ran the motor for about 15 min after the head swap. But then realized I had more work to do because I had used the wrong head bolts. So the headers came off again and I replaced all the head bolts one by one. I did not actually remove the heads, intake or distributor all over again. Just the headers and valve cover. I also tucked away some of the harness a little better behind the distributor. This is all I did, and now I'm getting this short.

red rock

iTrader: (2)

Did you read my post #12? This is why i said, you may have pinched some wires. Quote; [Recent changes were new heads and cam install. I did tuck away the harness behind the motor at the firewall a little better but didn't change anything] I guess i would start there. Next would be the starter and wires to it. Then the alternator and wires.

oamhmad

iTrader: (1)

Yep, read your post. I looked for pinched wires. In fact, today I pulled the entire harness that goes from the driver side to the starter out from behind the firewall. It's a non computer carb car so it was pretty easy.

I still have the short in ignition "run" and "acc" positions.

With the harness pulled away and disconnected from everything but the c100 connector at the driver side firewall, I tested the harness with the multi-meter probe on the large heavy gauge wire that attaches to the same post on the starter motor as the battery cable.

The short is still there. So this eliminates the alternator, battery cable running from battery to starter motor, and everything else that connects to the harness before it reaches the c100 connector.

The other passenger side ECM harness has been disused and tucked away for quite a while now since I'm not running any of the old ECM computer stuff.

No idea where to check next. I'm thinking...... pull the c100 connector and probe the power distribution terminals on the firewall side which would then eliminate everything in the engine bay completely.

QwkTrip

iTrader: (22)

You have the meter on the 20 mega-Ohm scale, All you're doing is measuring the resistance of all live circuits in the fuse panels. Complete waste of time.

oamhmad

iTrader: (1)

What range should i set the multimeter to then? Or is there a better way to verify a short to ground on the positive cable in the harness?

oamhmad

iTrader: (1)

Its the ignition switch. So seeing as someone pointed out i was using my multi meter incorrectly i set it to "continuity mode" where it beeps if there is continuity between the 2 probes.

so i turned the key to run very slooooowly and no beep = no more short!!! I was able to jiggle the switch back and forth a litte while still in run and it would beep intermittently. So it has to be a faulty ignition switch.

QwkTrip

iTrader: (22)

You're doing the same dumb thing, just with a a different setting on the meter. Look, this just isn't one of your skill sets and it might be best to get somebody to work on it for you.

The only thing you really know is you saw sparks at the battery. Wires that have good solid connections don't spark. Wires that are loose do spark. If I saw sparks from my battery then I would first check for loose or burned wires flopping around at the battery (where I saw the sparks). If the wires seem in good shape then I would make sure the battery terminal bolt is long enough for good thread engagement. If that checks out then I would snug things up again and see if problem persists. Keep fire extinguisher nearby.

oamhmad

iTrader: (1)

There were no loose wires or connections whete i saw the sparks. It was a short to ground.

I beg to differ. Sure, I might have wasted time...but i did diagnose a bad ignition switch using the so called "dumb" method, all in the spirit of DIY. I didn't buy this car to have others work on stuff i can't figure out on my own. Sorry I don't share your defeatest attitude.

New ignition switch and she'll be up and runing again !!

QwkTrip

iTrader: (22)

There is no short in your ignition switch. The ignition switch is wired directly to the battery. It is the switch that turns on almost every electrical circuit in the car. it is supposed to switch to battery when you turn the key. You have an old car so the ignition switch might be worn and not conducting intermittently (the opposite of a short), which may be the case considering your results.

You still have no evidence yet of an electrical short. Fortunately for you, a problem that doesn't exist is a problem that doesn't need to be solved so you might be happily on your way despite your best efforts.

red rock

iTrader: (2)

I hope you did find the problem, learning to fix things yourself can be a rewarding experience. With that said, there is a wealth of information on this site and on the internet, on how to properly use and trouble shoot electrical issues. Sometimes trying to explain how to do something on a forum can be misunderstood by both parties, and a good old how to video can be your best friend. Let us know if the switch worked or not.

oamhmad

iTrader: (1)

Then what exactly is continuity at the positive battery cable (disconnected from the battery) with ground, if not a short? This is the evidence.

Lurbie

iTrader: (3)

Dang, normally I'd leave the job of straight, to-the-point, direct, and somewhat insulting comments to the more seasoned members, but there is just so much stupid going on in this thread, I don't think they'll mind me taking one jab.
How does EVERY DC electrical circuit work?? It starts at the battery positive, goes through the load and goes to GROUND! All you're doing is measuring the ground on the other side of every hot at all times, or presently switched on, load. That load could be a starter, alternator, light bulb, etc... Like you've been told multiple times, a spark occurs because of a gap in a connection; but, I know you don't want to listen to that, so take your spark plugs out, smash the tip closed and tell everyone why it doesn't create a spark anymore. OR, fix your loose battery cable and enjoy your car again.

Lurbie

iTrader: (3)

OrangeBird

iTrader: (1)

There are certain devices , things like the memory in your radio for instance , and of course the ECM , that receive battery power all the time . In essence , you can not remove their load from the circuit without removing their fuses . With these always "on" electrical loads present , of course you will read "continuity" between the (removed from the battery) positive cable and ground , because what your actually doing is measuring the resistance of those always powered up devices !

I don't proclaim to be any kinds of "expert" , once someone calls themselves an "expert" their ego has grown too big for any new learning to take place , but I am a licensed aircraft mechanic (retired) and a lifelong electronics hobbyist . Take my word for it , what I've told you here is the truth , and the guys who've told you that sparks happen due to gaps in the conductive path are also giving you straight facts . I don't intend for this to be mean , but there ARE certain fields , electronics , brain surgery , those sorts of things , that really ARE better off left to those with a full understanding of the subject matter ......

QwkTrip

iTrader: (22)

An electrical circuit.

oamhmad

iTrader: (1)

Ok i get it. There was no short in the cable or ignition switch. I humbly accept my misinterpration. Continuity in the + cable the way i was testing, doesn't indicate a short.

The symptoms i had were twofold. Sparks and no 12v at the pink wire to the distributor. I guess the dead distributor wire was because of an intermittant ignition switch which I've replaced and the distributor is getting power again.

I still dont know what caused sparks. I pulled the battery cable out. It looks fine. Nothing is loose. The fusable link is intact
The battery terminal itself is also not loose in the battery.

skinny z

skinny z

Does this mean resolved?

QwkTrip

iTrader: (22)

Just to make sure.... by "ignition switch" you mean the box on top of the steering column that all the larger 12 gauge wires go to, right? Hoping you're not talking about the key cylinder.

Yes, you are correct, an intermittent problem with the ignition switch could shut down the engine. The Pink coil wire goes directly back to ignition switch and is powered by the main battery wires (doesn't go through the fuse panel under dash).

Those sparks could have been a wire that shorted to ground where the sparks were flying. If so, then you would find evidence of a burnt wire hanging there somewhere. If all the wires look good then slap it back together and see what happens. Keep fire extinguisher nearby.

Just for kicks and grins, how about showing us a picture of the battery and cables in that area?

oamhmad

iTrader: (1)

Ok so I slapped everything back to gether, set the main harness back in its position and hooked everything back up except the alternator. Ignition key in off position - positive battery cable back to + terminal on the battery and SPARKS!!!! Once again right at the + terminal. These were big sparks, definitely a short somewhere.


So I removed both the main engine harness connectors from the starter motor and supplied 12 volts directly to the larger heavy gauge + connector on the harness, removing both the car battery and the starter motor entirely from the circuit.

I used a different, smaller, RC toy 12V battery this time. No sparks. Everything looked normal. I was also getting 12V at the pink distributor wire with the key in the run position.

Not sure what's going on. I've attached a picture of the + battery cable and also the connections at the starter motor. Can someone please verify I'm wiring the starter correctly. Connector A to terminal A along with the battery cable and the small connector B to terminal B.

Correct. I'm not talking about the lock cylinder. I replaced the actual switch that sits on top of the steering column midway under the dash.

John in RI

iTrader: (167)

Here's a thought: Is it mounted backwards/upside down ?? or: Could the Steering Column Ignition box -to- Dash Harness plugs be installed upside down ??



***** Just throwin' it out there !!!


P.S. You should secure that wire shield ! If that thing touches the end of the wires and the starter,....

84 1LE

iTrader: (9)

Do you have the red sleeve that fits over the batt cable?Because w/out it the terminal can still be a little loose aven after you torque it down.

oamhmad

iTrader: (1)

It's wired correctly. The plugs only go in one way.

oamhmad

iTrader: (1)

Hmm, no haven't has that on the car for a number of years. Wasn't an issue before.



I think it's more than just a loose connection. I'm getting massive sparks as soon as the battery cable touches the battery, to the point where I have to separate the 2 immediately.



I'm thinking either the battery terminal in broken internally or I have the starter wired incorrectly or the starter itself has an internal short.

QwkTrip

iTrader: (22)

If you had just kept going and tightened the bolt then the sparks might have stopped. The GM side post style battery can spark like a SOB until the bolt catches a few threads. The trick is to press the cable terminal firmly against the battery until the bolt is snugged up.

The electric contact is made between the flats of the cable end and the flats of the pad that is inset in the battery. The bolt is there to clamp things together. Make sure the battery ring terminal is able to be set flat and not cocked in any way.

If you want to run an experiment then use a jumper cable to make the connection between battery and cable. The clamps close quick and easy so you can see if the sparks go away when clamped.

oamhmad

iTrader: (1)

ok will do. I have jumpers. In the meantime is there any test i can do with my multimeter to confirm there is no short? Im sacred of sparks igniting battery hydrogen.

QwkTrip

iTrader: (22)

If you really want to know what current is passing through the cable then you can buy a clamp-on ammeter at Sears or somewhere else. It has a loop shaped jaw that opens up so you can slip it over the battery cable and take measurement. You might have to plug it in to your multi-meter depending what type ammeter you buy. We can walk through that if needed.

Honestly, I'm not sure you're at that point yet. A dead short to ground would have already toasted something. Looking at your pictures, I have a feeling the battery cable end is shaped so that it doesn't sit flush against the pad at the battery. But it is hard to tell unless you're holding the real parts in your hand.

Don't have to worry much about the battery explosion as long as the battery has plenty of water in it and the hardware on the battery is in good condition. If you can't wriggle the battery terminal by hand then you're probably fine. I mentioned that earlier only because we hadn't narrowed down the problem yet. You can't do anything about the water level with a sealed battery. If the viewing window is still a green color then assume it is good.

QwkTrip

iTrader: (22)

Another option is to remove all fuses before attaching the battery cable to battery. That should remove all electrical loads with key off. If there are still sparks at that point then something could be wrong. After battery is connected then you can start plugging fuses back in.

Those little sparks you are seeing are nothing compared to what happens when a battery cable shorts to ground. If you had a short in the large battery cable to starter or alternator then it would be VERY DRAMATIC. Think "DC welder" kind of dramatic. Popping, sizzling, smoke, and possibly fire.

Lurbie

iTrader: (3)

Where is the other end of the B+ cable at the starter in your pictures? It should be on A in your picture?

oamhmad

iTrader: (1)

The picture just shows the wires hanging loosely in front of the starter. Nothing is actually connected. When i did wire it up i had the B cable on the B terminal and the A cable on the A terminal. The positive from the batt was also on the A terminal. (A & B being my own labels for the wires/terminal, not their actual names)

oamhmad

iTrader: (1)

Hooked everything up today. Absolutely ZERO spark when connecting the + cable to the battery. Car started up and ran fine. No sparks anywhere while cranking.

So in summary i don't know what the issue was, failing ignition switch aside. Whatever it was was fixed by pulling the entire harness from starter to driver firewall, cleaning up, cutting and taping loose uneeded wires and putting it all back together.

I also repositioned the tube metal shield at the starter cables because it was a little to close to the terminals and may or may not have been shorting wires to the body of the starter solenoid.

Thanks to all those helped out.