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Strange electrical problem in a 1972 Mustang?

Hi, I've got a lovely '72 'Stang that's got an annoying electrical problem. The car originally had an issue where the battery was not charging so I replaced the alternator, regulator and the starter (they were way overdue) and now when the car runs the charging system works as should be expected.

The wierd bit is this. When the car is off and parked the battery loses charge and loses it fairly quickly. I've not been able to find a bad ground (it would have to be a live into the body or engine to cause this bad of a drain) and the battery is about 2 years old.

Has anyone encountered this issue before or have any tips to see what's going on. I can replace the battery as well if I have to but I'm not really keen as money is already a bit tight.

Car starts and runs cleanly. All electrics appear to shut off cleanly but may be still pulling current in the background (no easy way I can think to check).

The car drains a fully charged battery in 2 days in the off position.

Update:

One detail I left out. Battery/Starter cables are new and are of good stock. The alternator cables are 36 years old but I've tested for shorts/bad grounds and found none there.

4 Answers

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  • Anonymous
    1 decade ago
    Favorite Answer

    It could be the battery - have it checked, but it is probably a slow drain, like a light inside the trunk or under the hood, or an incorrectly wired stereo system. Check these obvious things first, but also take the car to an Advanced Auto Parts and get the alternator and battery checked.

    1972 Mustangs are very cool - I hope you get this fixed soon. I used to have a 1964 1/2, and I loved it, and my first car was a 73 AMC Javelin, with a similar body to your Mustang. After the original 304 V8 died in the Javelin, I swapped in a Chevy 454.

  • 1 decade ago

    I had a Mach 1 at one time that had been put together out of three different Years Models. I installed a stereo wrong one time and it did the same thing to my Mach 1. If your alternator cables are that old replace them.I would also replace all other old wiring.Also if your battery is two years old you might want to change it

  • you will need a test light disconect the negitive battery terminal hook the test light between the negitive post and the terminal the light will come on if there is a short now start unpluging things one at a time start with the alternator than regulator than fuses when the light goes out hook every thing else back up except the last thing you unhooked if light is still out you know where your problem is

    good luck

  • Anonymous
    1 decade ago

    you could have a dead cell in the battery and not letting it stay charged.

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