I was stupid and installed my battery backwards while my 81 Corvette was running. On connecting it backwards, the engine immediately stopped. Now cannot start and no electrical circuit is working. I tested the battery, got 12 VDC and under the hood at a 6 wire connector block got 12 VDC on one corner (Red opposite Purple Ground) of the connector going down to the starter but none of the other connectors have 12 VDC but I think all of the 3 red/redwhite wires (2 corners and center of opposite side) should have 12 VDC. I checked several of the fuses on the fuse panel, circuit breaker and flashers but none were blown to open circuit. What do you suggest as my next step?
You most likely have a smoked fusable link wire. I cannot give you specifics because I cannot look it up on the infomation services I use because it is too old. However, most of the older GM vehicles had several fusable links that connected to the starter solenoid and provided power to the fuse block inside the car as well as the headlamps and some of the engine control circuits.
If you do find one burned, you have to figure out what gauge wire is in the fusable link. You can then buy some fusable link wire to match at most auto parts suppliers. DO NOT replace a fusable link with regular wire.
Hi againTom,
I am really glad that you found the problem with your Corvette. I just noticed that you stated that the wire was repaired with a wire nut. This is a big NO-NO that will come back and bite you at a later date. The correct way to make that type of repair is with a "crimp and seal" splicer. Wire nuts are for building wiring only, where the wires are not exposed to the elements or to vibrations. Using a wire nut next to the starter is asking for trouble. First, because it is exposed to the elements and wire corrosion can and WILL occur. Secondly, the wires at the starter are constantly vibrating any time the engine is running the wire nut can come loose and your wiring harnesses can light up and burn your entire car to the ground. (Trust me on this one - I have had to clean up messes caused by improper wiring repairs many times.)
The link below is a preparation test for people that are seeking to become certified automobile repair technicians. It is a VERY GOOD reference for performing high quality wire repairs for cars. Take the test yourself and see how much you know! It will give you the answers and also explain why each answer is right or wrong.
http://www.autoshop101.com/asetest/asete...
Hey Jeff - Just thought I'd mention that the diodes in the alternator are very UNLIKELY to be damaged by connecting a battery backwards. They can handle about 22 volts of reverse polarity at full charging system current - that is what they are DESIGNED to do. Also, burned-out diodes will not cause a "No-Voltage" problem in the rest of the vehicle circuits.
not likely a problem but easy to verify. If the diodes shorted, they could have been the cause of the blown fuse link, right?
Jeff - I suppose that could happen somehow. However, it makes sense to me that if the diodes were damaged, they would be OPEN not shorted. I do agree that James should verify his charging system voltage here just to make sure there is not any smoked diodes or a fried voltage regulator, etc..
EXCUSE ME... I meant to say TOM not JAMES!
yes, diodes almost always fail open, but we've all seen the odd case. system has taken a severe shock, so a little extra checking may be worth the time. I appreciate your feedback. Would you mind browsing my 95 stealth thread in the lounge. My day job is engineer--not mechanic, so all you guys that have more experience are a great blessing to me.
Jeff
Now I know my wire nut on the fuse link is only temporary. Thanks.
wire nuts are great in houses, but I always solder and wrap wires in cars.
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Not good. I would agree with checking the fuseable links and repair them as needed. The next place I would look is the Voltage regulator which is part of the Alternator so take it out and have it tested. If the motor isn't cranking at all check your starter relay which should be mounted drivers side near the firewall or drivers side front fender.
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disconnect the alternator and check again. You have probably shorted the diodes in the alternator. Check for any fusible links in your battery or larger power cables. If you see any, check the cable for continuity.
Thanks on Thanksgiving to all who helped me solve my 1981 Corvette electrical and starting problem. Thanks to the Lord for the good weather on Thanksgiving and Black Friday so that I could work outside in Pennsylvania without freezing my hands. The problem turned out to be a single fuse link that burned open near the starter motor in the starter motor wiring harness. That one fuse link seemed to be the only problem noted so far. The open was causing positive voltage to be absent from two of the three red/red white wires at that 6 wire connector block. Once the fuse link was repaired, with a wire nut, all three tested with positive 12VDC which started at the battery plus terminal to the center post of the starter motor then to one corner of the connector block and through the fuse link to two other wires which connected to the other two red/red white positions on the connector block. The car then started up as usual.
good job. check your battery voltage with the engine running to verify your alternator is still charging at least 14 VDC.
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