Electrical Short.

[Demps]

Check amperage for a current draw, vs voltage. That will show if there's a parasitic draw. There should be a small bit for powered items with key off.
Ted

[scottfab]

Putting the reason why you'd see 12v on the neg side of the pulled battery wire, why do you think there is a short?
What is the original symptom?
Battery runs down ?

[cvette98pacecar]

Originally Posted by scottfab

Putting the reason why you'd see 12v on the neg side of the pulled battery wire, why do you think there is a short?
What is the original symptom?
Battery runs down ?

Battery is on a tender always and it is dead, The tender can keep up with the drain.

[cvette98pacecar]

Originally Posted by Demps

Check amperage for a current draw, vs voltage. That will show if there's a parasitic draw. There should be a small bit for powered items with key off.
Ted

That was the next step after checking for a closed circuit, when the circuit should be open.

[Hib Halverson]

If you connect a volt meter between the batter and ground it will read whatever the battery voltage is.

If you connect an amp meter between the battery and ground you'll read current flow. There should be only a few hundred milamps.

From reading the other posts, I think you understand the procedure of using either a test light or an ammeter then pull fuses.

You might also have a battery which is, itself, shorted.

[Blue Flame Restorations]

[QUOTE=Hib Halverson;145886]If you connect a volt meter between the batter and ground it will read whatever the battery voltage is.

If you connect an amp meter between the battery and ground you'll read current flow. There should be only a few hundred milamps.

From reading the other posts, I think you understand the procedure of using either a test light or an ammeter then pull fuses.

You might also have a battery which is, itself, shorted.[/QUOTE]

Good point. I had an 84 month battery die today in my Silverado that only had 60 months usage. Had to replace it.

[Paul Workman]

Originally Posted by Hib Halverson

If you connect an amp meter between the battery and ground you'll read current flow. There should be only a few hundred milamps.

Ah, Hib... I believe you meant to say putting an ammeter in series between the battery post and that post's cable connector (have to disconnect the cable from the battery post to do the test). measuring current between the battery (positive) and ground creates a near dead short with the meter in the middle. If yer lucky, all it does is blow a fuse in the meter.

Robert-

because there is a path to ground through the radio and the ECM, etc that keeps the presets, clock, and memory alive, pulling the cable off the battery and then reading voltage will result in a voltage reading equal to battery voltage. If you were to disconnect the pos cable from the battery, and measure resistance between the positive connector and the negative terminal of the battery or to ground, you will see a few hundred ohms, but NOT infinity as there is a closed circuit even with the key off. (Somewhere between 240Ω and 1.2k Ω, after it settles, is normal.)

Back to the ammeter: Reading current between the positive terminal of the battery, and the positive cable connector (removed from the battery) you should have no more than 50mA (GM spec) , and typically 25mA or less. (Also note that when you first make the connection, the current will be considerably higher than that. That is normal. But, as the various capacitors in the electronics charge up (through the meter), the current draw will trickle down to its normal 10-50mA range before leveling off - usually after only 2-4 seconds or so. Once the reading settles, you can assess the normal "at rest" current draw, due to the "always on" stuff.)

The ammeter feature requires some special consideration: Move the read lead to the "10A" port on the DVM and select "A" on the meter BEFORE making connection between the battery post and the cable connector. To make the connections and then sweep the meter selector knob through the various ranges and such will more than likely damage the meter.

And! It is a good practice, once done makeing a current reading, to remove the test lead from the "10A" port on the meter and return it to the normal port. Otherwise you might do what I did yesterday. I forgot to move the red lead back to the normal setting before setting the meter aside. When I picked it up again to this time make a voltage measurement, I didn't notice the mixup until it was too late - and popped the fuse in the meter!

You may already know all dis chit, but I can testify that even if you've been doing "lectric chit" forever, it is easy to have a brain fart and forget to do something a pop a fuse...ask HIB and me how we know!!

P.

[cvette98pacecar]

Originally Posted by Paul Workman

Ah, Hib... I believe you meant to say putting an ammeter in series between the battery post and that post's cable connector (have to disconnect the cable from the battery post to do the test). measuring current between the battery (positive) and ground creates a near dead short with the meter in the middle. If yer lucky, all it does is blow a fuse in the meter.

Robert-

because there is a path to ground through the radio and the ECM, etc that keeps the presets, clock, and memory alive, pulling the cable off the battery and then reading voltage will result in a voltage reading equal to battery voltage. If you were to disconnect the pos cable from the battery, and measure resistance between the positive connector and the negative terminal of the battery or to ground, you will see a few hundred ohms, but NOT infinity as there is a closed circuit even with the key off. (Somewhere between 240Ω and 1.2k Ω, after it settles, is normal.)

Back to the ammeter: Reading current between the positive terminal of the battery, and the positive cable connector (removed from the battery) you should have no more than 50mA (GM spec) , and typically 25mA or less. (Also note that when you first make the connection, the current will be considerably higher than that. That is normal. But, as the various capacitors in the electronics charge up (through the meter), the current draw will trickle down to its normal 10-50mA range before leveling off - usually after only 2-4 seconds or so. Once the reading settles, you can assess the normal "at rest" current draw, due to the "always on" stuff.)

The ammeter feature requires some special consideration: Move the read lead to the "10A" port on the DVM and select "A" on the meter BEFORE making connection between the battery post and the cable connector. To make the connections and then sweep the meter selector knob through the various ranges and such will more than likely damage the meter.

And! It is a good practice, once done makeing a current reading, to remove the test lead from the "10A" port on the meter and return it to the normal port. Otherwise you might do what I did yesterday. I forgot to move the red lead back to the normal setting before setting the meter aside. When I picked it up again to this time make a voltage measurement, I didn't notice the mixup until it was too late - and popped the fuse in the meter!

You may already know all dis chit, but I can testify that even if you've been doing "lectric chit" forever, it is easy to have a brain fart and forget to do something a pop a fuse...ask HIB and me how we know!!

P.

Paul, this is exactly what I wanted to know. What are the live circuits on our cars! I knew the radio has the yellow leed which goes directly to a hot connection. I guess I should have went threw the wiring manual and found the circuits which are always hot. I should have done it the easy way, taking readings off the 91, than take readings off the 93.
That is what happens when you try to rush, chit get messed up.

[cvette98pacecar]

Originally Posted by Hib Halverson

If you connect a volt meter between the batter and ground it will read whatever the battery voltage is.

If you connect an amp meter between the battery and ground you'll read current flow. There should be only a few hundred milamps.

From reading the other posts, I think you understand the procedure of using either a test light or an ammeter then pull fuses.

You might also have a battery which is, itself, shorted.

That is what I think it is, the amp draw is .0256 which is 256mA. Guessing there is a dead or shorted cell in the battery. Identical to the 91

[scottfab]

Originally Posted by cvette98pacecar

That is what I think it is, the amp draw is .0256 which is 256mA. Guessing there is a dead or shorted cell in the battery. Identical to the 91

Point of clarification: If you see ".0256" that's 25.6ma which is not a big deal. If you did a typo and it truly is 0.256 (256ma) and is steady you do have a heavy draw. Time to leave the meter connected that way and start disconnecting stuff until you find the culprit. Do you have any aftermarket electrical stuff?