I had a noise coming from the rearend, seems like the left rear wheel was loose on the bearing, so bought new hubs and washers. Before I could get to that, I decided I better fix the leaking intake manifold (what a chore!). Meanwhile, I had bought a new battery but when I came back from Xmas vacation it was dead and all indications showed a massive short to ground. So, as long as the lots of stuff was unplugged and more room to look around than usual, I started in on the short. One day, I found that one of the fusible links from the distribution point showed a short to ground. A few days later, when I went back out to confirm, I found a short on a different wire on the distribution block and the first wire I had identified measured open to ground. Weird?

I subsequently got under the car and went to the area where I usually find massive shorts, the starter. The big fat cable from the starter measured open to ground, but the wire from the ignition to the solenoid measured shorted to ground. I also found a pretty good oil leak from the oil pan right onto the starter. Does anyone have any opinions on whether the short is most likely at the starter solenoid and not one of the wires from the distribution point? (Does it seem likely that oil dripped into the starter solenoid and shorted it out?) I don't want to keep chasing phantoms and I'm having trouble figuring out what else could have shorted while sitting (less mice interference, of course). My plan for now is to pull the oil pan and starter and have the starter tested, then hook up the battery and see if I still have a short.
Thanks!

 

I read this thread because I thought it was about shorts the daisy duke kind . It is getting warm here now !

 

Oil on your starter won't cause a short circuit! Unless you have an ohmeter that can accurately measure low resistance, the starter solenoid terminal on the starter normally has moderately low resistance AND that circuit is fused, so if your starter solenoid was indeed shorted, you would have blown a fuse or a fuseable link.
Also, it always helps if you post the year Corvette you are asking help for, no one here is clairvoyant!

 

Thanks for the reply. Do I get a spanking with that? I'm sure I entered my car in my sig several years ago, but I guess the software has changed, so I updated it today. It's a '91 automatic convertible. The more I thought about the solenoid, the less it seemed like the problem. There should only be a connection there when the key is in the start position, so that wouldn't explain the huge sparks when I try to connect the battery.

Maybe I should start another thread, but looking at the electrical schematics, I see more fusible links connected to the distribution point than I have on my car. Also, on the schematics, I see the fusible links labeled with a letter but no letters on the fusible links on the car. Does anyone know how to correlate the schematic to the actual wires in the car? I see numbers on the fusible links, but they are all the same color and the numbers don't seem to be of any use. Thanks!

 

If you're fighting what might be a 'trickle' discharge condition when the car is parked for days and in turn kills the battery, a good tool is an amp gauge.

most multi-meters these days used to check ohms, voltage, etc. have an amp function (although not a high amp rating - be careful as you can toast the multi-meter if you exceed the rating/range it can handle.

Start by just touching the positive battery lead to the battery to see just how much of an arc is generated. There will however be an arc since some things are powered at all times.

the amp gauge leads will go between the positive battery lead and the positive battery post. If you are using a multi-meter, be sure the leads are correctly connected to the meter and the selector is set properly. All Amps will be flowing through the meter/gauge. This will tell you how many amps are flowing from the battery when the car is off. Many time you can see the amp draw reduce as things like interior lights time out and go off, etc.

From there, you can start disconnecting things to locate the source of the amp draw. Keeping in mind that things like the radio and maybe the alarm system will draw some small measure of amps at all times...

 

Thanks for the well thought out reply. I am an electronics technician, so I am very familiar with amp gauges and voltmeters, etc. so I guess I'm not describing things well enough. When I got back from vacation, the new battery was completely dead. I recharged it and when I went to hook it up, got big sparks. I finally decided to go ahead and hook it up to see what would happen. I left it hooked up for only a couple of minutes. The car was pretty much electrically dead. No start, for sure. I don't remember if the lights were on in the interior, but it seems like there was just nothing. When I disconnected the battery and measured the voltage, it was down around 7 volts already. No fuses or fusible links seemed to have blown as a result which lead me to believe the problem had to be on one of the big leads from the battery (alternator, starter, something like that that's unfused). Since then, I've only quickly tried to connect the battery as I'm still getting the huge sparks with it recharged to 12 volts. It drops about half a volt each time I touch the negative cable to the battery, so I know without an ammeter that the current draw is very high. I don't really want to toast my battery by hooking it up and then trying to find the short by the smoke and heat (outside the area of the battery) or blown fusible link, if I can find it some other way. All of the upper side of the engine is all disconnected electrically now due to the intake manifold gasket swap.

I'm pretty sure one of the fusible links is shorted, but I'll be darned if I can figure out how to correlate the fusible links to the wiring diagram. So, I'm hoping someone can either tell me how to correlate or give me some other suggestions on where to look. What else could be drawing that much current if it were shorted without blowing a fuse or fusible link? What about the ignition or the theft deterrent system? Thanks!

 

I'm not sure how a fusible link can be shorted to ground. A fusible link is a piece of wire either intact or not intact. If it's blown, it's open and you should get no ohms measured from each end of the wire.

 

A blown fusible link will measure infinte ohms, not, "no", ohms!

 

ALL fusible links will measure as a short circuit because they are a short piece of wire of a smaller gauge than the wire coming from the battery and from the fusible link to the circuit. A fusible link is merely a fuse. All the wires that have a fusible link are the same color, red, and therefore if you want to identify what circuit they power, you have to either trace the wire, or disconnect it and determine what circuit is not working. If you have large sparks and rapid battery discharge, you have large current flowing in some fault, but not enough current apparently to blow the fusible link. What I would recommend is to disconnect all of the fusible link wires and either use a high current ammeter, or a high power light bulb, like a headlight in series with the battery and connect each fusible link one at a time to find the one with high current. If none of the fusible link wires is drawing high current, I would measure the current to the starter motor wire. You might have a stuck starter solenoid and at the end of the solenoid stroke, two large copper contacts are forced together to switch current to the starter motor. These contacts get pitted and blackened and eventually pass large current, but not enough to make the starter motor crank. Sometimes these contacts weld closed and don't allow the starter solenoid to retract like it does when you release the ign switch from the crank position. I believe the numbers on the fusible links indicate their current rating (not directly), not what circuit they are associated with.

 

Correct

 

I'm kind of liking your starter and solenoid scenario. I did start the car and run it for awhile before I left on vacation, so if the solenoid got stuck on that last start, that may explain what I've experienced so far. I measured 0 ohms from the solenoid power terminal to ground, with or without the wire connected. However, from the large power lead on the starter to ground is open. Wouldn't that be grounded as well if the solenoid is stuck closed?

There are a couple of numbers on the fusible links. I came to the same conclusion that one could be the current rating or gauge of wire. The other number I couldn't make any sense of. If it comes down to it, I guess I'll probably have to do the circuit elimination exercise. Thanks for the reply and the ideas.

 

Yes, the power wire to the starter motor would measure very low resistance if the copper switch contacts were stuck together.

 

You need to isolate and verify the current draw problem.

JFB is an Electrical Engineer.
I am sure he drew up many electrical schematics and designed many electronic circuits in his time and likely still does.

Sometimes the rectifier bridge or a single diode will short out in GM CS130 series alternators.
Simple to disconnect from the car.
Disconnect the Charging output wire & unplug the field connector.

Recheck for a current draw present or not.

BR

 

Put a test light between your battery negative and the ground cable. Unplug fuses to start with until it goes out or glows very very dimmly.

 

I disconnected the alternator while replacing the intake manifold gasket, so that's not it.
Thanks, though.

 

If you have what appears to be a solid short circuit that is not enough to blow the fusible link yet draw enough amps to kill a battery that fast, you should be able to isolate it reasonable quickly.

Take all the load wires (fusible links) off the jump start junction box, reconnect the battery (if it arcs now, it is at the starter motor as that is where the other fusible link (I believe) is connected) and start touching the fusible link wires one at a time to the junction box lug. You should at least be able to determine which one is causing the amp draw. Then, hook up everything else except the one that is causing the draw and see what does not work.

Head lights, dash stuff, etc. and then use the wiring diagram to reverse engineer which circuit is causing the draw from a component point of view.