Conversions & Swaps LSX Engines in Non-LSX Vehicles
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Old 05-30-2008, 05:21 PM
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Default alternator question

Doing my LS1 conversion into my 66 and am trying to make sure everything works prior to startup. I have power to the harness and all, have 11.5 volts to the harnessed wire to the alternator with ignition on. I spin the alternator (clockwise, normal rotation) and I get know voltage out. I'm using a drill with in the 1300 rpm range and show no voltage. With everything done above there should be output voltage right.

I have to make a parts run tomorrow and will have the alternator bench tested but just wondering if I'm off track here.
Old 05-30-2008, 05:26 PM
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Applying 11.5v to your alt trigger terminal is enough to damage the alt. This is the reason a resistor (or warning lamp )should be used between the alt and 12v.

Im not sure the alt is damaged but to be absolutely sure on its condition I would take it to an auto parts store for testing. They do that for free.
Old 05-30-2008, 09:49 PM
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Originally Posted by Schitzo
Applying 11.5v to your alt trigger terminal is enough to damage the alt. This is the reason a resistor (or warning lamp )should be used between the alt and 12v.

Im not sure the alt is damaged but to be absolutely sure on its condition I would take it to an auto parts store for testing. They do that for free.
The 11.5 volts is coming from my PCM, plugged into the alternator. I did not modify this at all.
Old 05-30-2008, 10:37 PM
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Are you using a 1999-02 f-body PCM, wiring, and alt? just trying to get an idea of whats being hooked together.

Also how is it hooked up when you are doing the testing? The alt needs the output terminal hooked to a battery to work (it uses voltage from there to power up the windings to generate a magnetic field and then generate power) Also I don`t know if the drill will spin it fast enough.
Old 05-30-2008, 11:09 PM
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Originally Posted by G-Body
Are you using a 1999-02 f-body PCM, wiring, and alt? just trying to get an idea of whats being hooked together.

Also how is it hooked up when you are doing the testing? The alt needs the output terminal hooked to a battery to work (it uses voltage from there to power up the windings to generate a magnetic field and then generate power) Also I don`t know if the drill will spin it fast enough.

yes 99 alt, harness, 02 PCM.

Have the alt wire (from harness) plugged into alt, single wire. Meter hooked to output wire.

So the output needs to be hooked up to batt power to produce voltage. Got it, will try that tomorrow. Will hook that up to the starter batt lead tomorrow and try it again. Should I see a noticable voltage output at the main alt output?
Old 05-31-2008, 12:05 AM
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With the engine running it will be a noticeable voltage increase ( battery is ~11.5-12.5 and with the alt running it should be 13.5-14) but I don`t know if the drill will spin it fast enough.
Old 05-31-2008, 11:51 AM
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Originally Posted by G-Body
but I don`t know if the drill will spin it fast enough.

You might be right. I was doing my math backwards regarding crank/alt speed ratio.




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