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DFWSupras
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1,627 Posts
Discussion Starter #1
OK Wednesday I got home parked the car (88 Turbo) and let my greddy TT count down from about 2 minutes. Next morning wake up and the car won't start. I look @ the Voltmeter and it's reading 6V so I jump start the car with my mom's Suburban. Car fires up. I disconnect the negative side of the battery to see if the alternator is working. Engine starts to shake a little so I figured it was the alternator going bad. I was on my way to work so I figured I would make it and I would change the alternator there were I had an extra one. Well I made it half way when the car dies. I get over and nothing has any power. I assume it's the alternator and call a tow truck. I get it to the shop and find the ALT fuse link burnt, the EFI fues burnt, Radio1 fuse burnt, ECU fuse burnt, CIG fuse burnt, and Cluster fuse burnt. But It didn't stop there. My ECU also got fried. The power antenna got hit so did the Profec A, Greddy TT, and the autometer A/F guage. I got the alternator tested and it bad. I replaced all the fuses took everything that got toasted out and replaced the ECU with a 7MGTE A/T spare I had (mine is a M/T) car runs now with the spare alt I had. The alternator kept it going @ first but now after a little while running @ idle it won't stay on with only the alt and no battery unless I rev it @ around 1-1.2K+ Any theories? oh and the Heart of Texas Shootout is tomorrow :(
 

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A battery acts like a voltage stabilizer or filter to the pulsating DC produced by the alternator. Disconnecting a battery while the engine is running can destroy the sensitive electronic components connected to the electrical system such as the emission computer, radio, audio system, cell phone, alarm system, etc., or the charging system because the peak voltage can rise to 40 volts or more. In the 1970s, removing a battery terminal was an accepted practice to test charging systems of that era. That is not the case today.

In other words: NEVER NEVER NEVER Pull the neg terminal when a car is running... ever.
 

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Super Moderator
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That sucks man, I hope you get things sorted out.

Maybe try busting out the multimeter and testing the coil packs?
The only other thing I can think of might be the IAC. I can't remember if it has its own fuse or not but that's worth testing.
 
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Ouch! :(

Sounds like your battery is either shorted, or totally dead. Replace it or it will kill your new alternator also.

As hawkeye pointed out, you should never disconnect the battery with the engine running. You can get some extreme voltage spikes coming through the entire system, frying everything in sight. Just like what ended up happening.

Man, I'd push my car off a cliff if I fried that many parts all at once. You have some enviable determination and patience. :)
 

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2/3 HP to the Paws
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1,519 Posts
How did you jump it the first time? If you connected the ground from the jump battery to the ground terminal on your battery (instead of the engine block), you can do several nasty things.

As well, as has been said, disconnecting the battery on a running engine is a dandy way to let the smoke out of basically every electronic component in the car. Punch whoever told you to do that in the head and never listen to them again.

If the alternator is dead, the brake warning and battery warning light will come on.

It sounds like you may have had a bad battery and/or a failing alt, and fried everything else trying to diagnose the problem.
 

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DFWSupras
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1,627 Posts
Discussion Starter #7
Well Heart of Texas Shootout was friday night and saturday. and I got the car running around 4pm Friday. I got an Optima Red Top battery only a couple months old so I doubt it was the battery. I replaced the alt with a new 70amp alt. that seems like it fixed it bacuse I drove it around for about 250 miles in 24 hours with no problem. Now I just have to replace all the non essential electronics that got fried. Anyone know where I can get a Profect A control unit that is missing the stepper motor/valve?
 
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