I just had a tread where my car would not start due to no spark. Came to find out it was a bad coil. I also had another tread sometime back where my voltage draw went to just over 16. I cleaned connections and replaced a couple of electrical components and got the voltage down to 15 and accepted that. After I changed the coil I did a quick run around the block and noticed the volt gauge I put in the car reading 14 so when I got back to the house I hooked up my hand held gauge and at above idle it was reading 14 volts.

My question is can a going bad coil make the ALT. put out more voltage?

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my first 6 1973 Plymouth Duster

My first thought is that a bad coil would draw the voltage down by drawing too much amperage, and possibly leading to a overheat (or fire!) wherever the fault was. The rare time that I had a high voltage it was the voltage regulator's fault- replaced that VR. High volts could cause the coil to work too hard and over heat and eventually fail, though. Always #1 common places for volts/amps issues though is always the battery cables. Check cleanliness of both ends of both pos & neg cables, and check the integrity of the cables swaged ends for internal corrosion or internal looseness. If you have aftermarket clamp-type terminals on the cables at the battery ends, disassemble the clamps from the cable strands and check for corrosion. Clean everything and reassemble with a water-displacing lube such as LPS-3 (waxy) or Vaseline petroleum jelly (drug store). That's my 2 cents. Anybody??

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"Louise", a 1976 Dart Custom project, (now sadly reverted to being just an "organ donor" to our other project Darts.)

Usually, you get higher voltage after the car starts up because the alt is recharging the battery and the regulator raises the voltage to do that. After you drive for several minutes, the voltage will come down, when the battery charge is topped off. I don't immediately see how a "going bad" coil would cause high voltage, and I bet the coil would fail quickly if it were.

Lou

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