JimmieLB

2004 C5 Commemorative Base Coupe. Battery voltage runs down from 12 volts to about 3 volts in a half a day when locked, alarm off, and everything off. I recharged the battery to 12 volts. I measure 2.2 amps between the negative battery connector (off the battery) and the negative battery terminal with the battery at 12 volts. I have removed all the fuses in the Under Hood Fuse Box and all the fuses and circuit breakers in the cabin Instrument Panel Fuse Box with no change in current. I still measure 2.2 amps. Any help would be appreciated. I can not use the Corvette with this problem. Thank you.

Learning_Curve

Try disconnecting the alternator and rechecking. It could have a bad diode causing a short to ground, and it's not protected by a fuse.

vipmiller803

The suggestion above is very likely.

Alternator, starter, or large gauge harnesses pre-fuse boxes are what it has to be since you're measuring the current to the car ground.

bobs77vet

you can also take the car to an auto zone and have the alternator checked....it will check the diodes...and the tester will give you a print out.

this is a likely source of your problem

JimmieLB

Learning_Curve:
Great Idea! I disconnect all alternator wires, no change. I had High Hopes. I am going to check the engine compartment Grounds and connectors to see if that might be the problem. The fact that I am measuring 5 ohm resistance and a 27 watts "load" could mean there is resistance somewhere in a ground connector and/or ground bolt where there should not be. Thank you for the Reply. Jim

Paul Wood

Check a couple of things. First make sure the light dimming wheel is in the off position. This wheel adjusts the intensity of the instrument panel but if turned all the way they will turn on the lights. Also check to see if any other lights are on after you turn the engine off and lock the car. You should not have any lights on. I know this is simple and basic but you might be surprised how many people have done this. Bill Curlee also has a post that gives you a detailed way to check for parasitic battery drain. Do a search. Good luck.

Paul Wood

Another common issue is the driver's side seat. The wiring for the seat motors below the seat can be shorted out if the foam is old and you are sitting on the seat frame. Seems like a pretty strong drain you are looking for and that would do it. Good luck

vipmiller803

A bad ground alone will not do it. How are you measuring the 5 ohm resistance? You can't just put it across the terminals with the battery connected.

If you're sure all fuses have been removed, you're likely looking at a short with the wiring somewhere between the battery and either fuse box, the alternator, or the starter.

JimmieLB

My 2004 C5 Corvette Commemorative Edition has a current “leak” of 1.7 amps when everything is shut off measured between the battery negative CABLE and the negative battery terminal. Solved the problem for now. First, my Ammeters was bad, all fuses were blown. I do not know how it read anything. I used a 20 amp scale for the later checks. The “leak” I read was 1.7 amps varying from 2.1 amps to 1.5 amps in sort of a pattern, before I removed anything to check. I pulled all the fuses and relays from the Underhood Fuse Box, no change in “leak” current. When I pulled fuses in the Instrument Panel Fuse Box at the Passengers feet, the current reduced when I pulled fuse 5, Radio/CD, by 1.2 amps and the leak current was constant, not variable; pulling fuse 25, BCM1/IPC (Body Control Module/Instrument Panel Cluster), reduced the current by 0.4 amps; pulling fuse 30, DCM-R (Door Control Module-Right), reduced the current by 0.1 amps; pulling fuse 33, DCM-L (Door Control Module-Left), reduced the current by 0.1 amp, leaving a negligible current leak. These add up to 1.8 amps, within the range of the variation of 1.5 amps to 2.1 amps.

1.8 amps would drain a 22 amp-hour Optima Battery in 12 hours. My first solution was to pull fuse 5, 1.2 amp drain, Radio/CD, but that put out the clock on the Radio that I missed. My final solution, so far, was to install a Knife Switch on the battery negative post that I open after I driving the Corvette. Luckily the Alarm does not sound when I close the switch to drive. I will look into having the Radio checked and refurbished.

JimmieLB

My 2004 C5 Corvette Commemorative Edition has a current “leak” of 1.7 amps when everything is shut off measured between the battery negative CABLE and the negative battery terminal. Solved the problem for now. First, my Ammeters was bad, all fuses were blown. I do not know how it read anything. I used a 20 amp scale for the later checks. The “leak” I read was 1.7 amps varying from 2.1 amps to 1.5 amps in sort of a pattern, before I removed anything to check. I pulled all the fuses and relays from the Underhood Fuse Box, no change in “leak” current. When I pulled fuses in the Instrument Panel Fuse Box at the Passengers feet, the current reduced when I pulled fuse 5, Radio/CD, by 1.2 amps and the leak current was constant, not variable; pulling fuse 25, BCM1/IPC (Body Control Module/Instrument Panel Cluster), reduced the current by 0.4 amps; pulling fuse 30, DCM-R (Door Control Module-Right), reduced the current by 0.1 amps; pulling fuse 33, DCM-L (Door Control Module-Left), reduced the current by 0.1 amp, leaving a negligible current leak. These add up to 1.8 amps, within the range of the variation of 1.5 amps to 2.1 amps.

1.8 amps would drain a 22 amp-hour Optima Battery in 12 hours. My first solution was to pull fuse 5, 1.2 amp drain, Radio/CD, but that put out the clock on the Radio that I missed. My final solution, so far, was to install a Knife Switch on the battery negative post that I open after I driving the Corvette. Luckily the Alarm does not sound when I close the switch to drive. I will look into having the Radio checked and refurbished.

JimmieLB

jcgunn

2.2 amps is a big number, I would be concerned about a short causing a fire. Keep the battery disconnected until you figure this out!

Bill Curlee

Did you disconnect the BATT Terminal off the back of the alternator and install the DC AMP Meter between the wire and the terminal? You SHOULD see ZERO AMPS. If there is any current draw, the diodes are leaking.

You need to determine if the excessive current draw is coming from the under hood fuse box OR the passengers foot well fuse box.

There is a B+ terminal on the under hood fuse block. Disconnect BOTH wires on that terminal and make sure that you keep the actual battery lead safe.

Once you have BOTH fuse boxes isolated, use the DC AMP Meter to connect either the under hood box or the passengers foot well box to the actual battery power lead.

See if one draws the excessive current. REMEMBER!! Make sure that you wait the full 12 min before you say that it actually is drawing excessive current.

Please post the results.

JimmieLB

Bill Curlee:

JimmieLB

Bill Curlee:
Thank you for your reply.
I have not tried some of the items you mention, but I will.
I just posted a Summary of my effort to date at the end of my Thread. I noted the fuses from the Instrument Panel Fuse Box and the current drains for each of the 4 with my crude measurements. The battery is disconnect when I remove each fuse, then measure the current after I close the passenger door with everything else off. I did not wait 12 minutes to make the measurements, but probed the ammeter across the negative cable and terminal to make the measurements.
I installed a Knife Switch on the Negative Battery Terminal that is my Solution for now.
JimmieLB (Simi Valley Corvettes)