Hello all, I am new to this forum and have been having some agonizing problems with my corvette.

Some background: I’m 24, a Civil engineering student at Purdue University and I inherited this car from my father when he passed away. I know that he used to frequent this forum so I thought this might be a good place to get some answers.

The problem I have been having is that the electrical system is draining so much that after about a 15 minute drive the battery goes dead and the motor stops. I can either let it sit overnight to start it again, or put a charger on it. At first I thought it was the alt so I replaced that, no luck. So I then replaced the battery, still no luck.

About 5 minutes before it dies the battery indicator light comes on.

It also has an aftermarket stereo installed.

Thanks all,

Chris


EDIT: It is a 1990 auto, non-Lt1 motor

 

Well I am no expert on Corvettes but it appears to me the alt. is not charging, so get that checked first. While you are checking that you will need to have a good battery when checking for a draw... place a test light in line between the battery poss post and the battery poss cable terminal. If the test light is lite up you will need to start pulling fuses one at a time till the test light goes out. REMEMBER...if you have a door open or hood lights you will need to disable the switches for this test because you will create a false draw if they are operational while the test is being performed.

Do these couple of tests and post your results and we will try to help you further.

Sorry for your loss... what was your dads screen name? We have had an awful lot of loss here lately, alittle more than usual... this can't be good.

Good Luck
Dana

 

You have a new alternator and battery and these are of good quality I assume. You have a significant "short" issue if your fully charged battery will only run the car for about 15 minutes. Does the battery drain down with the ignition key off? If so, this may be a clue to your problem. Otherwise, the comments of Justardnck are the best advice I could give you.

 

I was thinking that the alt was bad even though it is new... I have had many remans come out of the box bad. I still say have the Alt checked out again. A running car with a bad alt will drain the battery quick (maybe not as fast as yours but still have it checked out).

 

i havent ever done this on a vette but have on other cars start the car get it to where you can get the postive terminal off the battery while runing if the car dies the alt is bad if stays running yo u got something else drainingyour battery could be the hood lights i know alot of people unhooke those for this reason mine is good luck

 

Do NOT remove any cables from the battery while the car is running. You run a significant risk of frying the ECM if you do this. On the old non-computerized cars you could test your alternator with this method but not with the newer computerized engines.

 

Sparks from connecting/unconnecting cables near the battery (including jumper cables) can cause battery explosions too. Very impressive explosions I might add (I was glad I was standing further away then the others).

Sounds like alternator to me. If you can get it started it should run without a battery. The battery could be bad too but I would start with the alternator and see where that leads. Some shops can check alternators it you want to make sure before spending money.

 

So are you saying use a test light with the + cable disconnected or connected?

 

No it does not, which is why I can leave it off overnight and it will start in the morning again.

I was thinking that it was the aftermarket stereo that was installed by a stereo shop, but I will try a new alternator first.

I don't know what my dad's screen name was on here but I should be able to find it once my mom gets back into town and I can get to his email account.

 

i wasnt sure about the vettes i thank you for letting us know this ....

 

Opelgt73: Just a suggestion for you! Take the alternator off and have it tested by Advance, Auto Zone, NAPA, etc. before you buy a neew one. They will test it for you at no cost! BTW on the 15 minute battery "drain down" time! A battery draining at this rate will create a lot of heat and the electrical engergy is transformed into heat. Do you notice anything getting hot? Any hot smells?
SAM

 

No I don't notice anything getting hot which is why I am starting to belive that it is indeed the alternator, if the alt wasn't working then I would think that the ignition would drain the battery by itself.

 

AFTERMARKET STEREO???? Just a hunch, but what kind of system ? If your running a large amp it can kill the stock charging system. The alt can't keep up with a 1000 watt amp and the rest of the car's eletrical system.

 

could you have a bad ground some where????

 

It's an Eclipse system, just a head unit and 4 eclipse speakers mounted in place of the bose system. My dad had it installed by a stereo shop and at the time there were problems with the speakers cutting out and we had to take it back a few times. I think I am going to pull out everything that they did, install the 4+1 channel eclipse amp that I have along with a 10in sub. I am going to use solder and heat shrink instead of those crimp connectors though.

I know that he had to take it to a specialist to have the computer reprogramed for use with an aftermarket stereo, could that have anything to do with it?

 

Get a multi meter. A cheap one (under $10) will do fine. Put it on DC voltage and check output at alternators large red wire post with car running. Should read 13.7 to 15+ volts.If not your new alt is bad. If good then check same at positive post at battery with car running. Should be near the same(13.7 to 15+ volts) with maybe a little loss. If not, and the alt output is good, then check the connection at alt for hidden corrosion and follow the wire to either to power distribution junction down behind/below battery or to battery depending on year. Check/clean all connections there. If it goes to power distribution junction down behind/below battery then you need to check and clean wire from there to positive post of battery. Clean it all up and check again.

Alot of times the problem lies somewhere inbetween the alt and battery. Good luck and let us know.

 

ok I am putting a charger on it tonight,

Tomorrow I'll run it and check those voltages with my multi meter.

 

Do this with the battery cable disconnected... in a nut shell you will complete the battery connection with your test light.

1) remove the possative battery cable (with the car off)
2) clip the test light to the batery cable
3) stick the point of the test light in to the battery post (on the battery)

If the test light is lite up... something is drawing.

Finding the draw is much harderbecause anything that uses power in the car could be drawing so make sure the under hood lights are off or disconnected.
If you open the door you will have a draw because you comanded the interior lights to activate.
Personally I would check the lights in the mirrors on the sunvisors... ecause a passenger could have left it on (these are not enough power draw to kill the battery that fast but try it anyway)
If you open the pass door to pull the fuses you will need to find a way to disable the door light switch. See if you can have someone... anyone stand by the battery while you pull the a fuse observe if the test light goes out... if not... put the fuse back in and try another untill the light goes out.
If you go through the entire fuse block and still cant get the light to go out you will need to dive deeper. There are a couple of small fuse blocks in the car but they are year specific and you will need to consult a manual for your car.
There is also a main battery feed on the alterntor which could cause a draw it it were bad so you may want to try and pull that to see if the light goes out.
There is one more thing you can try to trace the problem down but it very complicated and you WILL nee a EVTM (Electrical, Vacume, Technical, Manual). To do this you will need to remove the battery and still have it hooked up which would require you to have some heavyduty jumper wires. Behind the battery you will find several fusable links (orange in color... I believe) and they will all be mounted on one post. You will need to remove those one at a time and see which one causes the light to go out. Then trace the wire and the circuit from there.

I know this long but you have a complicated concern so I hope this helps.

Dana

 

Dana you the man!
I said the samething many posts back about the disconnected post and light check and someone of infinite wisdom said that you'd never get anything with that check.

Some folks try to check for a drain with the battery hooked up and that will give a battery check only.

Anything that pulls that kinda draw has to be the battery or the alt. Many people will miss a dead cell short.
Guess that 40k in tools wasn't a waste afterall?

I agree with ya, I've worked in car/truck shops for 40 years and the worst part of the job is the customer. Them and the flatrate. Everyone I know who owns a shop says the samething.

I don't miss it either.
So now you're in construction?

 

I left the auto industry out of frustration (I have many complaints) A friend was a stock broker and talked me into lying to his boss to get me in, after hearing the money he was making it didn't take long to twist my arm. I did that for alittle over a year and couldn't live with myself anymore. I made an insane amount of money at it so I took the entire next year off to do some sole searching and figure out what I wanted to do with my life. During my soal searching I decided to help a friend out as a helper to kind of kill the time and try my hand at other professions. Well as it turned out he wasn't a licensed Contractor(I didn't know this) and in Florida thats a big NO NO. Well we got caught and both got dragged into court I tried to explain to the judge that I was mearly a day labor helper but they wouldn't hear of it and we both got fined pretty big. I decided that there was a lot of money to be made as a contractor (as well as stick it in the judges a$$). I have a strong automotive electrical back round and I realized that Gate and Telephone entry systems operate very similar to automotive electrical systems. So I went to work for a local fence company as a peeon and 3 years later the boss and I had a big blowout (IMAGINE THAT....I DON'T HAVE AN ATTITUDE PROBLEM )

Well to make a very long story short my old boss was trying to blackball me so I couldn't work in the construction industry. I decided to stick it in his a$$ too and become his competition... now 3-4 years later(and at a cost of $10,000 and 6months of studying) I own my company and I have 60% of the large accounts in Palm Beach County (how do ya like me now...Steve ) most of these were his accounts (they came to me, I didn't solicit them).

The rest is history


as Paul Harvey said

"And now you know, the rest of the story"