Parasitic Battery Drain!!!

Feb 15, 2015
1978 Pace Car
Hey Guys!
I need some Electrical Genius up on here! My battery keeps going dead within a week. The battery itself is fine, keeps a charge on the bench if not in car. I have a 200mA draw on my battery. I tried removing every glass fuse underneath driver side dash, draw never goes away. Tried disconnecting alternator, draw still there. How do I fix this?



High RPM Poster
Jul 1, 2017
2017 3LZ Z06 Z07
Not sure about your Pace car but all C6s and C7s require a battery maintainer be plugged into the cars otherwise the computers will drain the battery in a short time.

Maybe your 8 track player is shorting out a bit... OK i'm just kidding. Parasitic draws are a bugger to find. GM dealers have a device they can plug in to help you narrow it down. I have had limited success with this on my H1 Hummer that had the same type of issue.

Basically it may come down to trial and error with a meter.

Maybe some other guys with C3s can give you a direction to start with.
For sure I would buy a battery maintainer and leave it plugged in in the meantime. Cheaper than replacing the battery. Hopefully you sort it out before it gets worse or becomes a short and dangerous.... although the circuits should be fused.

Good luck

Black 03 Z06

High RPM Poster
Oct 30, 2013
Haliburton, Ontario
2003 Z06
Wasn't there someone who recently joined the forum who was an automotive electrical expert? I remember making some crack about a toaster but cannot recall his name.

Anybody else remember.

OP good luck these electrical gremlins can drive you nuts. If you are in the garage can you shut off all light sources to see if there is a bulb glowing somewhere. Glove box, under hood, trunk light, licence plate bulb maybe the dash lights? Is there anything that does not function any longer but could still be drawing power?


High RPM Poster
Jan 27, 2009
Township of Langley, BC
1975 coupe/2003 vert
Good idea with the dark garage Murray..

hotjay... You do not have parstitic(?) loss..that is usually on the later computer controlled models, C4-C8.
Constant searching of modules and sensors causes battery drain.
On a C3-C1 you have a problem as almost everything shuts off when you remove the key, except if something is plugged into the ‘always live’ cigarette lighter.
Your idea of pulling fuses and disconnecting the alternator is sure the right place to start.
Has anyone ‘monkeyed’ with the wiring before you got this car(or since?)..
Add-on audio system?

Power seats. I don’t have those but they may be energized even with the key off?

If I think of anything else I’ll be back
Good luck.

Nov 16, 2015
St. Albert
2018 Z06
A 200 milliamp draw may be a normal draw for that car. A bad battery only needs a small draw to make it dead quick and if this battery has gone completely dead even once then you'll probs need to change it. If you feel that the drain is the issue there is another way to investigate besides your method. Keep the meter on between the post and cable and unplug stuff like the wire to your distributor. I don't think you can cover all your circuits just by pulling fuses. Good luck.
Feb 10, 2018
Corvette 2017 Z51
I don't know the C3's at all, but if you've taken out all the fuses and it still drains, it could be a live wire somewhere that is on the main harness and over time has vibrated against the body/ground. That would suck because it means hunting a lot. Thankfully the C3 has less gadgets than later models so it should make this easier (a bit) to find.

One thing you can do, set an amp-meter to display that 200ma drain, and then wiggle some wires/cables. If it momentarily drops, you might be getting close.

Also, while your amp-meter is plugged in, disconnect the ECU, just to see if that drain could be coming from that. (assuming C3's have some sort of ECU, again, not familiar with them).
Apr 30, 2012
2005 C6 1SB
With our 2005 six speed 1SB car, I put it in reverse, put on the emergency brake, shut the car off and never have a problem. I have a C-tek battery tender for winter storage. Had the car since 2012. The electrical systems in these cars are my one worry. Knock on wood that problems don't start for me. Fortunate so far.