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I am restoring a '66 Mustang convertible with a 200 CID with automatic transmission and power steering. I have had difficulty keeping the battery charged. With assistance from a retired Ford mechanic (he worked on the '66 Mustangs when they were delivered to the dealer in '66) and friends, we have changed the coil, the battery, installed new belts, wiring harness for the alternator, rebuilt the wiring harness under the dash and changed the alternator. In fact, just last night I replaced the alternator for the 4th time. The rebuilt one was checked by O'Reilly's and it checked out ok. But, when I installed it and returned to O'Reilly's it showed less than 12 volts. This is the same result I have had with the other alternators. We have also installed a Pertronix ignition system and an electronic choke. The car runs ok until the battery discharges. The lights are dim when driven at night. Remember I'm not a mechanic so if you have any ideas as to a solution, please try to keep the explanation simple. Any help or suggestions will be appreciated. The other local Mustang club members have run out of ideas. Thanks, in advance. Also, when the radio is used, after a few minutes, it blows the fuse.
 

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Hey Ozark,

Where in the Ozarks are you? I'm in Joplin, MO. You might try calling Missouri Mustang in Webb City, MO (417-673-1990) and see if they can help. They've been a huge help to me when I've had weird problems.

Tom
 

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When I have charging system problems, I look at the voltage regulator first. I don't see it on any of the above description of repairs. Tell ya what. Do a "full field" test of the charging system. If it pops up to 14-15V, you have a regulator problem. If it doesn't, you have a wiring or alternator problem.
 

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Discussion Starter #5
We replaced the regulator with one that was working on a street rod. Could you describe a "full field" test? Remember I'm not a mechanic. Thanks.
 

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There is a crimp splice in the middle of the wiring harness that is completely hidden. I had similar problems. The wiring harness was a current new replacement. That splice had not been fully crimped and was actually causing the problem. I re-crimped the splice and things have worked since. Rare, but could be a problem.
 

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I had a similar problem a couple years ago with a '67. I talked with several electrical experts, and finally had one refer me to Ron Francis Wiring troubleshooting folks. Even though I had not purchased their product, they talked me through all the symptoms, and finally convinced me I had a grounding problem. I ended up running all grounds to a common ground strip, and the problems went away...why, I don't really know, but I battled this off and on for about four months, changing alternators, etc.
 
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