Question 1997 C5 Bty Leak To Ground, Advice Needed

Gummiente

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The battery will drop to 12.2V overnight unless I put a battery charger on it. The battery was load tested and the alternator out put checked and both were fine, which leaves a current leak to ground as the likely culprit. I disconnected the ground cable and hooked up an ammeter; as soon as the connection was made a servo or relay somewhere near the right headlight whirred for a second and the meter showed a draw of 1.4A. It gradually decreased until levelling off at .3A.

I'm new to Corvettes, have only had this car for a few days. Can anyone point me in the right direction as to where and what systems and components to check to find the problem?
 

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@Gummiente right from brand spanking new the C5's had issues with the electrical systems and batteries self draining. If you can find shop Manuals for your car the place to start is to find and clean all the grounds on the car, think there are five major ones but could be wrong. I leave the battery tender on mine when the car is not in use. Your car is 20 years old and you have to expect some challenges with ownership. Do not be dismayed, you will get it figured out and piece by piece get everything ship shape again.

It is difficult when you really have no idea of the maintenance of the car but just go forward and you will learn much about your car and the satisfaction of having fixed it. Good luck... :thumbs:
 

rfh928

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The battery will drop to 12.2V overnight unless I put a battery charger on it. The battery was load tested and the alternator out put checked and both were fine, which leaves a current leak to ground as the likely culprit. I disconnected the ground cable and hooked up an ammeter; as soon as the connection was made a servo or relay somewhere near the right headlight whirred for a second and the meter showed a draw of 1.4A. It gradually decreased until levelling off at .3A.

I'm new to Corvettes, have only had this car for a few days. Can anyone point me in the right direction as to where and what systems and components to check to find the problem?
Just a tip...I'd check if you have a dry cell battery in there. While it was convenient having the C5 battery under the hood for easy access vs the tight compartment in the back hatch of my C7...there are some electronics right under the C5 battery, and if the battery leaks it can cost a lot of money to replace them. I bought my C5 used many years ago, and it was one of the first things I was told as well. Thankfully the previous owner had put in a dry cell battery, and I put in 2 more over the 15 years that I owned it. A Delco dry cell battery is about $350, but worth the peace of mind.
 
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Gummiente

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Just a tip...I'd check if you have a dry cell battery in there. While it was convenient having the C5 battery under the hood for easy access vs the tight compartment in the back hatch of my C7...there are some electronics right under the C5 battery, and if the battery leaks it can cost a lot of money to replace them. I bought my C5 used many years ago, and it was one of the first things I was told as well. Thankfully the previous owner had put in a dry cell battery, and I put in 2 more over the 15 years that I owned it. A Delco dry cell battery is about $350, but worth the peace of mind.
Nope, previous owner put a fecking Wal-Mart sealed lead acid battery in there. I have to take it out to get at the passenger side windshield drain hose anyway, so I'll make sure to check the electronics underneath it.
 

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Nope, previous owner put a fecking Wal-Mart sealed lead acid battery in there. I have to take it out to get at the passenger side windshield drain hose anyway, so I'll make sure to check the electronics underneath it.
I'd be getting a dry cell battery ASAP if I were you :canada:
 
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rfh928 absolutely correct. When I bought my used '99 it had a brand new battery in it and A/C did not work properly. Thought this all fishy so looked under battery and it was all acid leak damage. The battery posts on C5's are side mount and they sometimes leak. Big problem is the main control module is underneath as well as the main wiring harness. To make a long story short I had to pull the right front fender to get at this mess. Luckily the harness and computer were OK, but the vacuum hose for the air conditioning was eaten through. Rubber or neoprene thought were impervious to acid, but I was wrong. Had to pull intake to replace hose, but I did the whole job myself for less than $15.00, Went straight to my battery guy and bought a dry cell battery for around $150.00. I am guessing his job at a repair shop would be around $1500.00 so GET YOUR DRY CELL BATTERY NOW!
 
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The battery will drop to 12.2V overnight unless I put a battery charger on it. The battery was load tested and the alternator out put checked and both were fine, which leaves a current leak to ground as the likely culprit. I disconnected the ground cable and hooked up an ammeter; as soon as the connection was made a servo or relay somewhere near the right headlight whirred for a second and the meter showed a draw of 1.4A. It gradually decreased until levelling off at .3A.

I'm new to Corvettes, have only had this car for a few days. Can anyone point me in the right direction as to where and what systems and components to check to find the problem?
I agree with OL Yeller. I took the bulb out of my underhood light. I am getting old, had a lot of vehicles, never had a leaky lead acid battery. I have an acid absorbing mat under my lead acid battery in my C5 just in case. Whether you change your battery or not, there is still the parasitic draw issue. YouTube says that anything over .05 amps is a problem. Lots of videos on how to attack the problem.
 
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Gummiente

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Had a bit of time to work on it this morning; the hood light was burnt out and there was no corrosion on the terminals, but I removed the bulb anyway as I prefer to use a flashlight when I'm mucking about in the engine bay. Removed the battery, all the wiring underneath looks good. Shot some WD-40 on the two grounding posts in the battery box area, will remove and clean the rust off the terminals another day, as well as continuing the troubleshooting process.
 
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Are the battery posts on the side of the case or the top? If they are side posts, and even if they are not leaking, I would still change over to a dry cell.
 

Gummiente

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My experience has been with AGM (Absorbent glass mat) but maybe other people will have different thoughts.
AGM is what Harley has been using for many years (I recently retired from the Parts counter at the local dealer) and it has worked out well. The Lithium Iron batteries are new tech and I'm still on the fence about those. I'll go with a new AGM for my C5.
 

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AGM is what Harley has been using for many years (I recently retired from the Parts counter at the local dealer) and it has worked out well. The Lithium Iron batteries are new tech and I'm still on the fence about those. I'll go with a new AGM for my C5.
Sounds good. Shop around, you can save a lot if you search.
 

Gummiente

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New AC Delco AGM battery installed today with the cutout switch on the negative post because I still have not located the source of the ground leak fault. All the grounding points I found were in good shape, but were cleaned anyway. I have not found any obvious rodent damage to any of the wiring in the engine bay, so the next step is to pull fuses one at a time to see if I can narrow it down to one circuit.
 
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New AC Delco AGM battery installed today with the cutout switch on the negative post because I still have not located the source of the ground leak fault. All the grounding points I found were in good shape, but were cleaned anyway. I have not found any obvious rodent damage to any of the wiring in the engine bay, so the next step is to pull fuses one at a time to see if I can narrow it down to one circuit.
Sounds good. Now time to get your Battery Tender for the winter.
 

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