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Salmontheotherpinkmt
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4,043 Posts
Discussion Starter · #1 ·
Does anybody know what the alt is supposed to put out at idle on a 2003 svt?My Batt light came on and i checked the volts and with the motor off it had 13 and when it was running it only putting out 13.68 so i guess my alt is bad is what im thinking.
 

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C2H5OH
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11,867 Posts
The output voltage is based on load. If you had a bunch of accessories running (lights, radio, heater, heated seats, etc) the voltage you measure will be lower. basically at idle you'll probably see around 13.5 or so. Idling most cars won't run full charge. But if you rev it up a little and hold say 1,500rpm you should see closer to the 14.5 mark. If not then you may have a charging issue which could be a bad battery, the alternator itself or something messed up in the wiring (pigtail perhaps).
 

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Salmontheotherpinkmt
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4,043 Posts
Discussion Starter · #3 ·
yea im still on the batt that came in the car new.I had to take it back not long after i bought it to have the alt replaced.All the wires look good and the batt light hasnt came back on yet so i guess i will have to wait and see if it comes back on
 

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The Librarian
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13,116 Posts
13.68v is plenty acceptable.
When you start hitting 12-12.5v when it's running is when you need to start worrying.
14.5v is just shy of over charging voltage...that's about as high as you want to be.

iminhell is correct, in that the voltage will vary by load.
Try turning everthing off, take a reading, then turn on lights and heater, and see what it comes up with.

After that, check the wiring at the alternator.
You may have a connection that's getting loose, or wiring that's ready to break.
That would explain the intermittent light.
There is a repair harness/pigtail for that very problem (loose/frayed wiring).
 

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Salmontheotherpinkmt
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4,043 Posts
Discussion Starter · #5 ·
13.68v is plenty acceptable.
When you start hitting 12-12.5v when it's running is when you need to start worrying.
14.5v is just shy of over charging voltage...that's about as high as you want to be.

iminhell is correct, in that the voltage will vary by load.
Try turning everthing off, take a reading, then turn on lights and heater, and see what it comes up with.

After that, check the wiring at the alternator.
You may have a connection that's getting loose, or wiring that's ready to break.
That would explain the intermittent light.
There is a repair harness/pigtail for that very problem (loose/frayed wiring).
yea i was getting 13.68 with everything off and the car at idle.I checked the wires and they looked good.So im not sure whats going on, its doing what it did when i first bought it and took it back under warranty and the dealership installed a new alt and wires to the alt.It has 90k on it now so i guess it time for stuff to start going out on it.[rant]
 
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