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Discussion Starter #1
The problem is... I can't drive at night because the car dies a few miles after I turn on the lights.

The background is... brand new Die Hard, new voltage regulator, all new wiring from the firewall forward, new headlights, rebuilt alternator, new battery ground cable.

Any help would be great!!!

New user, James

65 Fastback 289 4v
69 VW TypeIII 1.5l FI
00 Saturn SW2 1.8l FI
 

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You can drive it as long as you like during the day? What's the voltage across the battery terminals with car running, both with and without head lights on? You should have around 14-15 volts.

I'd suspect the alternator, even though it's new. W'e've all bought tons of parts that didn't work right out of the box.

If you always do what you've always done,
You'll always get what you've always got
 
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With out the headlights on it will run forever. I can't test the battery right now I am replacing the distributor. I'd hate for it to be the alternator... it's the third one I've tried.

65 Fastback 289 4v
69 VW TypeIII Fastback 1.5l FI
00 Saturn SW2 1.8l FI
 

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Gone but never forgetten
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Sounds like a gnarly short in the head light/tail light circuit that's frying your alternaterors.

Since you've replaced all the front harnesses, I'd first suspect the tail light harness. It makes lots of nasty bends around sharp metal and is held in place at the tail light panel by more sharp metal clips. Start with a visual inspection.

If a visual doesn't turn up anything, it's still going to be easiest found with a volt meter across the battery terminals. My guess is you're going to see the normal voltage (around 14v) with the lights off, but a drop down below 12 with lights on.

If this is the case, umplug the tail light harness under the dash (orange/blue and green/orange pair plug). Then see if you have normal voltage.

If you always do what you've always done,
You'll always get what you've always got
 
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being a newbie myself, i hesitate to give advice, but I had a similar problem on my 68, as soon as the lights came on the battery would start going down. Cut to the chase, the alternator (second new one) can be wired in more than one way, there is an extra terminal that not every application uses. After some hard looking at photos in a mustang repair manual and a little wire moving I got it right and it started working with no more problems. Check it out.
 
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