1981 Chevrolet Corvette Won't Shut Off

1981 CHEVROLET CORVETTE
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JNORRIS482
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I have a 1981 Corvette which I purchased about 6 months ago. I bought it to play with, but I think it's playing with me! I just had the 350 built new from the oil pan to the carb. When I went to get it back from the shop, the mechanic said you need a new battery, this one has been dead for a few months. We jumped it off and I drove it home. When I got there I went to shut the key off, but the car kept running. The only ways to stop it are to put it in reverse(maybe a park sensor?) or to push the electric window switch.... If you just tap the switch, the car will briefly miss a lick and still run. But if you hold it, it will shut the motor down. It will do this after the key is OFF and completely pulled out of the ignition. So I replaced the battery, and drove it for a while. I got home, shut it off (with the window button), and fired it right back up. Started back up fine, and this time it shut off with the key. I got home the next morning and the brand new OPTIMA Red Cap battery was dead. I jumped it off and drove it again. Came home and the battery held a charge from the alternator. I fired it back up and let it run for a little while. I shut it off with the window switch again.A few hours later it was dead again. It has a complete aftermarket MSD ignition system on it, which is practically new. Checked the fuses, but none are blown. The steering column is a little loose. I've tried shaking it when the key is off, but it just sits and idles. Can You Please Help Me???????????
May 10, 2006 at 8:52 AM
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LOSONE
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First check all grounds to the engine and everwhere the ground cable goes. Shiny clean. Do the same with the + side.

Most of the time when an older vets keeps running is from the alternator bleeding through internally from the red wire to the brown wire. It will also cause the battery to run down. Insure the battery is charged and disconnect the red wire to the alternator, start it and see if it shuts off. Also leave the red wire off and see if the battery still discharges.

Let me know and I'll give you some more info
losone
May 10, 2006 at 9:32 AM
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JNORRIS482
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O.K. Pulled the clip out of the side of the alt. The car started and shut off just fine. The wires looked good, but there was some sort of oily greasy substance where the clip goes in. I cleaned it off, and fired her up again 4 or 5 more times. Everything shut off perfect. I guess I will let the thing sit overnight to see if the battery runs down or not. If it does, how do you suggest I diagnose the problem. Is there a routine you guys use to try and locate problems like these??? Please let me know, and thanks for your help so-far. Justin
May 10, 2006 at 10:07 AM
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LOSONE
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I am an old retired garage owner with over 40+ years behind me. What I have just told you and it seemed to work indicates you have a bad alternator. Remember I am in Biloxi, Mississippi and your a "fur piece" away.

They are not expensive for that engine about $45.00 for a good one. Change it and you should be fine. the brown stuff is probably the winding insulation melted.

If you battery runs down, I give you some steps, but I don't think it will.

Make sure the connections are not burned or look like the connection can touch. One of the wires is battery and the other is ignition. When they touch, it won't let your vet shut off and the battery will run down..
May 10, 2006 at 10:51 AM
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JNORRIS482
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The alternator is only about 6 months old, has been used maybe 90-100 miles, and charges very well. The brown stuff is like oil. It is not at all hard or firm. So far the car has held a charge, and is not dead. I just blew the bottom radiator hose due to the A/C hose rubbing against it. I'm pretty mad, so I'm giving up for the night. I will reply in the morning, to let you know how the battery holds up. If it goes down I will charge it immediately, and disconnect the alternator, to see what it does. Thanks so much for your help. You all are really good people for doing this. I am a Sheriff's Deputy in Nashville TN, so I can't really help people the way you all do, but I would if I could. Thanks again, and I will talk back with you in the morning. Justin
May 10, 2006 at 12:24 PM
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LOSONE
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I hope you left the wires off the alternator to see if your battery was OK over night.

If you went to the "Zone" don't be surprised it is a bad alternator. The only thing i buy there is if i can pour it out of a can or bottle. I have see starters and alternators cleaned, painted and put back in a box.

Justin, in your line of work you do much more for people than I. As a former 1sgt in Security Police, I know what you do and thanks

Lee Parmeter
May 11, 2006 at 12:18 AM
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JNORRIS482
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O.K. Last night I got back down there and put the new radiator hose on. I played with the car for a minute just to see if it will continue to turn off by itself. It started acting up again. It wouldn't turn off with the key, but if I pulled the alt. wires it would turn off. If I clean the connections on the alternator clip, it works fine for a little bit. The battery drained last night, but I still had the clip plugged in. I charged it up last night, and pulled the clip this morning. I will see what it does now. Do you still think it's the alternator??? Thanks. Justin
May 11, 2006 at 3:18 AM
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JNORRIS482
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Alright. Pulled the clip out of the alternator that has the red and brown wires in it. When I do this, the battery light and choke light are lit up on the dash. Not sure what to do about this, because I think this will run down the battery as well. Any ideas??? Thanks. Justin
May 11, 2006 at 7:15 AM
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KREJR
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I've got an MSD ignition on my Jeep and had the same problem with the vehicle running after the key was off and in my pocket. Check your manual for the ignition, but you'll likely have to run a resistor in series with one of the MSD wires to solve the problem. Apparently these ignitions need very little juice to keep going, so a resistor will solve the problem. I don't know what to tell you about the charging issue though. Good luck!
May 11, 2006 at 1:23 PM
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LOSONE
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Let me tell you how to find a battery drain problem.

Buy a digital volt meter that has an Amp scale. (about $20.00)

Disconnect the negative battery lead.

Put the meter on the 10Amp scale. Put it in series with one lead on the battery and the other lead on the ground cable.

This will show you the battery drain in Amps. A perfect set up like your car shouldn't be over 25MA (.25AMP) and that will be the radio memory.

I would pull the fuse for the interior lights so openng the door won't affect the meter reading.

Make a list of everything you do.

1st take a reading with everything connected, record it. Next pull the alternator wires including the big red one and take a reading. (one at a time)

When the reading drops you have isolated a battery drain.

You can isolate shorts/drains in good order that way by disconnecting wires that control something. I have used this method hundeds of times so it works.

It takes all the guess work out of the process.. E mail me directly at losone@cableone.net and I will post the final findings on the site.
May 12, 2006 at 12:32 AM
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Suggested Repair

Clean engine and battery grounds and the positive cable connections. Unplug the alternator connector (red and brown wires): if the engine then shuts off with the key, replace the alternator because it is bleeding power internally and can also drain the battery. If the battery still discharges, measure parasitic draw with a digital meter on the amp scale in series between the negative battery post and cable, then disconnect circuits one at a time until the draw drops. Normal memory draw should be about 25 mA.

Conversation Summary

A 1981 Chevrolet Corvette with a rebuilt 350 and aftermarket MSD ignition kept running after the key was removed and repeatedly killed a new battery. The owner found that holding the power-window switch or shifting to reverse would stall it, and that unplugging the alternator connector made it shut off normally, though cleaning the oily connector only helped briefly. The expert attributed run-on and drain to internal alternator bleed between the red and brown wires and recommended replacing the alternator after confirming with the connector unplugged. The expert also gave an ammeter series test on the negative cable to isolate any remaining parasitic drain. Another owner mentioned an MSD resistor fix for run-on, but the charging and shutoff tests pointed to the alternator.

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