so on my 89 battery charged, disconnect NEG terminal put one lead of my volt meter on the terminal and other on post. wow shows battery voltage! big draw. go to passenger side fuse panel pull every fuse out and circuit breaker amazing no change on volt meter!! like what!! reinstall all fuses go over to battery. 3 terminals coming off it, 1 fuseable link disconnect it. NO change. hook that back up, 2 heavy red cable runs around back of battery to distribution block 10mm bolt on it, remove that still NO change!! only cable left is big cable on battery which im guessing going to starter. Is the starter causing my 12V draw??? so confused did i miss something ANY HELP OR DIRECTION would be really appreciated thank you

 

It's pretty obvious that electrical stuff is not your strong suite. All those readings are normal. Please define the problem you are trying to solve.

 

yes not my strong suite. Trying to fix a battery draw problem, with the volt meter between the NEG terminal and NEG cable im reading 12V, theres three leads coming off POS terminal disconnected two there was no change. have not got under car to disconnect starter cable to see if draw goes away. thanks for your help man

 

Did you remove the under hood fuse for the heater fan? It is fed off the cable on the starter.

 

You are measuring voltage. There will always be voltage when you test like that. It doesn't prove anything!

If your battery is going dead in a short amount of time, that's a problem, but you haven't said that's your problem. I'll ask again: Why are you doing this testing?

If that's your problem, you need to be checking current drain (Amps), not voltage (Volts).

 

Yes sir the battery is going dead over time. the other thing i have done is looked for a draw across the fuses. car off key out all the door buttons pushed in let car sit for a bit. then set my DVOM to mil amps and put across each fuse. they way i was taught to check for a draw was take NEG battery off put test light between terminal and post if it lights there is current flowing or draw, i just used DVOM because i had it out. thanks

 

OK, how many milliamps is the meter reading?

 

Yes it will show voltage regardless due to the ecm, ccm, radio, etc.

 

You can't check for draw with a voltmeter. Sometimes ameter will spike as modules wake up, and blow meter fuses. If you use a test light light would be bright then after a few minutes fade. If this is the case ; to protect meter connect a jumper in parallel with DVOM after a few minutes disconnect jumper and read meter.

 

If you set the voltmeter to measure "amperage" and put the meter's leads in between the battery (-) post and the battery cable connection on the NEGATIVE side of the battery. This will measure power leaving the battery. Normally these Corvettes have a small current draw of ~.3 amps or less. Be careful with your multi-meter as most have a low limit of current measurement and any current draw of 10 amps or more will toast a lot of fuses in meters. I use a Fluke 88 meter working on my Corvettes as it is able to help test virtually everything electric on my C4, and it has a 20 amp current reading ability.

Start by measuring the battery voltage. Measure it with the battery disconnected and then after it is connected again. Be sure that the battery connections are good and clean and that you are starting with a fully charged battery. Once connected measure and record the voltage at the battery. Now measure the voltage at the Fuse Panel, what are the numbers? I would wait ten minutes or so and measure the voltage again or at whatever intervals you like but measure and record the voltage. If do this for 24-48 hours away from the car without charging and you will see how bad the self-discharge rate is.
The typical FLA Self Discharge Rate was probably something like ~1-1/2% of the capacity per month when new. It can double and even triple as it gets older. Some batteries get shorted internally as the lead sheds off the plates and can short out in the bottom of the battery. I saw a battery explode in a Van once as it was shorted internally and just exploded one day. It sure made a mess of the van. My C4 had a electrolyte leak once as I found burns in the paint from the acid on the side panels and the bottom of the drivers door. It was popular to break the battery case to disable the alarm system before stealing a Corvette in the old days.

How old is the battery? Is it holding a charge when left by itself unconnected from the Corvette? If it is a standard Flooded Lead Acid battery like the batteries of yesteryear? After a FLA battery is in use for a while the self-discharge rate goes up and the battery will use more electrolyte and need to be recharged more frequently to prevent loss of capacity. Have you checked the electrolyte in a while? If the electrolyte is left low for a period of time the plates will become oxidized and the battery capacity will be reduced. Batteries REQUIRE maintenance and are frequently forgotten as long as they work. 1 in every 4 breakdowns of Cars is caused by the battery. I strongly suggest to every Corvette owner to maintain your battery and your Corvette will always be there when you need it.

What happened when you disconnected the battery wire at the starter? If the connections were not tight that would allow resistance and make heat. Check your starter solenoid for any signs of heat or burns.

The alternator has diodes that can blow and cause a current drain from the alternator. If that happens you might see AC voltage on you DC wires going to the battery and this is not a good thing for EFI Corvettes. It is an easy test, simply put the meter on Voltage measurement and set it for Alternating Current and see what there is coming out of the alternator. Measure between the Positive and Negative connections with the meter set for AC. If any AC is found you might want to replace the alternator. Alternators generate AC and it is converted to DC by a Diode Bridge inside the alternator's case.

Did anyone install any options on the Corvette after it was made? On the later C4's the interior light timer is a suspect, this is why we wait for a few minutes for the car to shut down. Harbor freight makes a tool which allows you to see how much current is being drawn thru a particular fuse circuit. It is cheap and very useful for verifying the current being used on each circuit, simply remove the fuse and install the tool in place and it has a read out showing the current draw.

I hope that this helps a bit! I will be watching for your answers.

Best regards,
Chris

P.S. Other common power drains are Power Seats and Power Windows with improperly functioning limit switches. Try unplugging your power seat harness' and see if the load drops.

 

OP said had removed all the fuses from the fuse panel, but what about the circuit breakers on the panel? IIRC there are 4 in there also. I had a power drain on my 86 which turned out to be related to the power seat switch in the console. Until I removed the circuit breaker, I was unable to locate the issue.
Also HF sells a meter that you pull fuses one at a time, plug the fuse into the meter and plug it into the slot the fuse was in. It will tell you how much current is flowing through the circuit, up to 30 amps IIRC.