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Old 09-12-2007, 09:40 PM
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Bad ground?

Hope you guys can help.
78 Firebird T/A w/Pontiac 400.Electrical power completely cut out on me on the middle of the road (engine cut off too) I have power going to fusebox,but when I turn the key to any position but "off" I lose power at the fuse box.the hazard lights,headlights,horn don't work,even when I have power at the fusebox.Here's the weird part.When I relocated the ground wire from the battery,to a clean bare metal spot,I had power for 2-3 seconds,then everything died.I did this 3 times and each time I will have power for a few seconds.I replaced the ignition switch already,so it cant be that and the battery is at 100% according to my charger.I'm ready to buy a new wiring harness.
Could my charger be giving me a false reading? Is there another ground somewhere I'm not seeing? I am using one of those cheap testers with the alligator clip and the light.Will these light up for any amount of voltage?

Thanks,

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Old 09-13-2007, 12:50 AM
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Electrical lies and voodoo

Your battery charger won't show a battery with a shorted cell. I'd take it to get tested under load.

If it's not a shorted cell in the battery, sounds like grounding gremlins to me. Start with the basics. Remove and clean with a wire brush both ends of all battery cables. Clean the battery terminals with a wire brush as well. Evaluate the cables themselves as they could be in bad shape and often too small in diameter anyway. If they are original, replace them anyway for peace of mind.

The negative battery cable should be firmly mounted to a clean bare metal spot on the engine. There is also a ground cable that should go from the engine to the body. Find it and clean each side.

If it were my car, I'd replace that wiring harness anyway. I'm sure someone has hacked it up and the insulation is likely getting brittle and may be not doing it's job and may even be falling off in places if it ever see any significant abuse.

Steve
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Old 09-13-2007, 07:50 PM
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Battery is good,now what?

Thanks for the advise.I had the battery tested today at AutoZone and it's good.I will have to check all the ground connections and go from there.Are there any other grounds other than the one from the battery to the engine?I know every electrical component has it's own ground but are there any others that if not connected would prevent the car from starting?
Also, the battery is grounded to the cylinder head but the engine is not grounded to the frame or body.the car ran ok like this for the week that I drove it.(I just bought the car)
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Old 09-13-2007, 08:13 PM
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also check your fusible link.
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Old 09-13-2007, 09:59 PM
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Detective

Hmmmmm time to play detective then. Yes, it COULD be the fusible link, possibly partially melted. Find it and check it out. Check where the main power wire comes into the fuse panel and look for broken wires, corrosion etc. It should be the largest diameter wire.

Find the ground wire that goes from the engine to the body. USUALLY from intake or head to the firewall. Clean connections.

A couple of things to check just to try to eliminate some things. Without starting the car, turn on the headlights and see how bright they are.

Check the wire that is on the same terminal as the battery cable on your solenoid. Look for broken or corroded connections and clean them anyway. Follow the large alternator wire back to where it meets a battery connection, usually at the solenoid, but not always. If you can't find it or figure it out, get you a digital volt meter (Sears and automotive parts stores) and measure voltage at the battery while it's running. Should be over 14 volts.

Again, re-evaluate the diameter and condition of the battery cables. If they are thin, or you see any sign of a white battery acid-like corrosion, or green coloring on the wires, trash them and get new cables. I'd probably do it anyway if they are original. Get a larger diameter than stock.

Pull the fuses and check for condition and clean connections. If all looks ok, disconnect the battery and remove the fuse panel and look behind it for anything unusual.

Chances are in doing all of that you'll find something not quite right. If not, at least we eliminated a lot of stuff and confirmed things were right in those areas.

Steve
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Old 09-15-2007, 06:09 PM
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Thanks

Thanks 58Apache for your help.I'm sure you could guide me through this but
this has now become less than fun.I have come to this conclusion.Hotrodding is fun,but when it drives you crazy,it's time to pay a professional.
Thanks again
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Old 09-15-2007, 06:24 PM
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You need a good ground from the negative battery post to the engine block...then one from the engine to the frame, and another one from the frame to the body. Make sure that all your ground connections are free from grease, dirt, rust, and paint. You want good clean metal to metal contact....also best to use a star washer. Do this and I believe your problem will go away.
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Old 09-16-2007, 09:08 AM
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Challenging

Quote:
Originally Posted by dean7276
Thanks 58Apache for your help.I'm sure you could guide me through this but
this has now become less than fun.I have come to this conclusion. Hotrodding is fun, but when it drives you crazy,it's time to pay a professional.
Thanks again
Wiring and electrical problems are probably the least understood and most challenging to hotrodders. However, it's not as hard as people make it out to be. I realize it's hard to understand something you can't see and requires special knowledge, but it CAN be done, and if you're going to do ANY electrical modifications to your car in the future, you're going to need to dive into this area...unless you can afford to pay someone else every time you have a problem.

While electrical is one of my specialties, guys like Centerline have proven to me that you can learn almost anything and do most things yourself if you try.
Just have patience and do your research, and don't give up too easy.

I think you will learn a lot if you buy a new harness and re-wire your car. The wires are labeled as to where they go, and there are instructions in the kit, plus tech support from the manufacturer. Besides insuring you know how it's wired, you would reduce likeliness of fire and continued electrical gremlins.

I'll assist here if you need it. BUT, I'm a soldering kind of guy, and I'll freak if you/anyone just crimps. Whenever those jerks on the TV and motorcycle shows crimp the wires only they are showing how amateur they are in this area. Soldering insures a good connection (if done properly) and greatly reduces future problems.

Steve
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