Dead again
Thread Starter
Racer
Joined: Dec 2012
Posts: 487
Likes: 66
From: Rhode Island
Dead again
HI everyone. I just can't get a break. my 70 all. done that what I thought next day the new battery was DEAD come on give me a break so I charged it took it out for a ride took it too my speed shop and hard the timing check its ok started right up took it home and it was charging so put it. to bed .next day DEAD.so started poking around with the fuse block. and with car off I had power to all the fuse on the left side which one was for the brake light so car off key out I step on the brake pedal and the lights came on.something is live all the time and drawing the battery DEAD any body have any clue where to check ,I think this is going to be HARD Thanks for your help bob
Last edited by bobby70; Dec 6, 2022 at 09:25 PM. Reason: spelling
Race Director
Joined: Apr 2011
Posts: 11,183
Likes: 3,335
From: North of Toronto - Ontario
Clock, lighter, courtesy lights,
Tail lights
Stop and hazard lights
Instrument lights
Are all powered without the key on
The other side of the fuse block is switched with the key
Heater
Wipers
Radio
Signals / backup
Gauges
Pull the clock fuse and nothing else should be "running" with the key off
Start there, if you have a good ammeter you can check each fuse (pull the fuse and check over where it was plugged in) and see if you can tell what circuit it's on.
There are a few other circuits that don't go through the block, alarm etc but start where it's easy to check
M
Tail lights
Stop and hazard lights
Instrument lights
Are all powered without the key on
The other side of the fuse block is switched with the key
Heater
Wipers
Radio
Signals / backup
Gauges
Pull the clock fuse and nothing else should be "running" with the key off
Start there, if you have a good ammeter you can check each fuse (pull the fuse and check over where it was plugged in) and see if you can tell what circuit it's on.
There are a few other circuits that don't go through the block, alarm etc but start where it's easy to check
M
Race Director
Joined: Mar 2017
Posts: 11,949
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From: Virginia
If there is a bad diode in the alternator, that could be the problem, too. This seems to be a common failure mode on the Forum, and is not fused either (well, not in a way that is easy to test).
Melting Slicks
Joined: Sep 2006
Posts: 2,815
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From: Wichita Kansas
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
to ease the pain you need an ammeter to
show the drain.
a test light may give a hint.
basically hook meter/ light between pos bat post and disconnected pos cable.
the meter/light makes the connection.
note amp draw/light brightness,
make sure door lights are off and hood light off, key off.
disconnect alt pos wire
pull fuses and note any amp drop
good luck.
carefull amp meters average @10 amps max and could break if you try to crank engine.
show the drain.
a test light may give a hint.
basically hook meter/ light between pos bat post and disconnected pos cable.
the meter/light makes the connection.
note amp draw/light brightness,
make sure door lights are off and hood light off, key off.
disconnect alt pos wire
pull fuses and note any amp drop
good luck.
carefull amp meters average @10 amps max and could break if you try to crank engine.
Race Director
Joined: Nov 2006
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Most common drain that would pull battery down overnight is indeed a bad diode in the alternator. Yes it will still charge fine.
simple test. Remove large wire from alternator when you shut down the car. If your battery is still good in the morning you found your issue.
simple test. Remove large wire from alternator when you shut down the car. If your battery is still good in the morning you found your issue.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
And in some cases there were the hidden light bulb constantly on.
On some models the bulb in a rear compartment.
Other models had a spare tire carrier courtesy light.
Unless your garage is pitch black, you would never know it was on.
On some models the bulb in a rear compartment.
Other models had a spare tire carrier courtesy light.
Unless your garage is pitch black, you would never know it was on.
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Safety Car
Joined: Mar 2006
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From: Chester VA
Yep, this happened to me a couple of times. The lid in the center rear storage compartment wasn't fully closed and latched, causing the bulb in there to remain on.
Thread Starter
Racer
Joined: Dec 2012
Posts: 487
Likes: 66
From: Rhode Island
ALOT good info and forgot to. say that I was trying to adjust the carb but no power to the chock and my friends speed shop hook it to the alternater never had a problem with it but its something else to check alot of good info so out to the garage and start checking thanks you guys bob
Thread Starter
Racer
Joined: Dec 2012
Posts: 487
Likes: 66
From: Rhode Island
WELL went out to the garage and started looking around and the overide switch was off then unplug the alt and pulled all the fuse out and still getting power to the whole left side of the fuse panel this one will kick my ***
Team Owner
Joined: Jan 2007
Posts: 53,648
Likes: 878
From: Southern Cal Ca
St. Jude Donor '22
unhooking alt will not kill power to the car.
until you start with something between bat cable and bat to show the drain, nothing can be learned
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
OP:
Do you have a camera on your phone? Take some photos and post them (air cleaner assembly off). Perhaps we'll see something obvious.
Do you have a multimeter and know how to use it? Do you still have a power draw with ALL fuses removed? That's a useful data point, but you need to measure the current draw.
Do you have a camera on your phone? Take some photos and post them (air cleaner assembly off). Perhaps we'll see something obvious.
Do you have a multimeter and know how to use it? Do you still have a power draw with ALL fuses removed? That's a useful data point, but you need to measure the current draw.
Thread Starter
Racer
Joined: Dec 2012
Posts: 487
Likes: 66
From: Rhode Island
OK guys look around today found one problem but it was not the problem can some one just press the brake pedal car off to see if the brake lights come on I. have a friend. coming over on Friday to check the alt and diode but will that kill a battery in 3 hours thanks bob
1967 Pedal Car Champion
Joined: Mar 2020
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From: US-PNW
OK guys look around today found one problem but it was not the problem can some one just press the brake pedal car off to see if the brake lights come on I. have a friend. coming over on Friday to check the alt and diode but will that kill a battery in 3 hours thanks bob
I'd advise a battery cut-off switch for your car. Regardless of your current issue, you really should be cutting all power to the car when not in use to protect against a short-caused fire.
Last edited by barkingrats; Dec 8, 2022 at 09:56 PM.
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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How to find a battery drain
https://www.corvetteforum.com/forums...with-pics.html
Yes, the brake lights will come on when the key is out.
Yes, the brake lights will come on when the key is out.
Thread Starter
Racer
Joined: Dec 2012
Posts: 487
Likes: 66
From: Rhode Island
ok great at least I know the rear lights not the problem ,I had this car 22 years put every thing new complete frame off rebuildi the ac complete wire harness never had a short have a 1000 w stereo I don't want to set up my sterno or clock every time I get in the car this is just me if the car is correct you don't have to unhook the battery the car was at the body shop for 8 month the clock was correct and it started right up when the snow flies it gets put away I don't unhook the battery but I still keep a battery tender on it plus plenty of insurance.if it burned to the ground then I will buy a c8