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Discussion Starter · #1 ·
Hello,
On my 70 Chevelle, I recently replaced the positive battery cable that leads to the starter. After doing so, I fired it up and went for a drive. As I pulled out of the driveway I saw smoke coming out from underneath my hood. It turns out that the cable that goes from the negative battery terminal to the left side inner fender (grounding strap) was totally burnt and smoking. I got it back up to the house and went to change it out. After cleaning off the cables and ensuring a clean contact surface for them all, I fired it up with the same end result. The odd thing is that with the key removed from the ignition, when I attempt to put the last battery cable back on the terminal, I get sparks, indicating a connected circuit. Any ideas on where to start hunting for this short? I appreciate any help.
- Patrick Bellene
 

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I would look at what you changed and what changed since last time when it didn't have a short and look real close at that first.
Possibly a melted through or rubbed through positive cable going to the starter or from the starter to the junction block ?. Or maybe a hold down clamp on the positive cable on the frame or fender ?. Maybe the terminal end on the starter cable at the starter is hitting something ?.
Jim
 

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The negative cable to the block is bad. The starter is using the fender ground and motor ground straps to start the car. The lighter 12 gage wire can't handle the current and burns.
 

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That was my initial thought but since my intial thoughts are usually wrong I thought I should think it through. What about the sparks when hooking up battery cable? Made me think there may be another problem. Once started does the ground wire continue to fry or does it eventually cool down?
 

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Originally posted by Finally:
That was my initial thought but since my intial thoughts are usually wrong I thought I should think it through. What about the sparks when hooking up battery cable? Made me think there may be another problem. Once started does the ground wire continue to fry or does it eventually cool down?
There should be no sparks when connecting the cable. I had a car in two weeks ago and he had a battery drain and his arced what I would call slightly (1.5A current draw and I could hear the arcing and see the spark jumping the gap) but once I tracked it down to a vanity mirror light staying on and disconnected it the amperage draw went down to 0.01A and if there was arcing I could not hear or see it then. That small amount was from the memory circuit on the radio for the presets and clock.
Do you have any stereo amplifiers, MSD box, door open, trunk open, etc that could be making the arcing but is not out of the ordinary and if so try disconnecting them or closing the doors to see what happens. Some amps I hook up at work will arc on the power or ground connection for the first time to charge up capacitors inside of them and if they sit a while disconnected off of a power source the caps will discharge and when hooked up again will arc a second time but if I disconnect them from power and reconnect them right away they don't arc as the caps do not have a chance to discharge.
If it is a ground problem like John_Muha suggested then be glad it only fried an easily replaced connection and not a shifter cable like in a buddy of mines 69 Grand-Prix. His lost the engine to battery ground through the big cable and fried the shifter in the park position. That one had us scratching our heads.
Jim
 

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Discussion Starter · #7 ·
Thanks for the reply's guys. I appreciate the help. I'll inspect the condition of the negative battery cable and clean off the grounding location to the block.
 

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Discussion Starter · #8 ·
Turns out that my positive battery cable was too close to one of my header pipes and grounded out on it. After replacing it, it works great again. Thanks for the help.
- Patrick Bellene
 

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Yea if the short was to the frame or body I could see the ground strap frying. Since it's to the engine that does sound like a bad negative cable/connection. Who would think that a car that's only 34 years old would have 2 electrical problems at that same time.
 
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