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steffen707 · 04-08-2012, 03:08 PM

Disapointing update guys:

I went out and performed a bunch of tests with the alternator on, with it in low mode, and then I shut the car off, pulled the 4 pin plug from the alternator, started up the car to do an alternator off test and my volt meter was reading 14volts..WTF!? HOW IS THIS POSSIBLE.

So I remembered a thread where people said you need to soft ground the yellow/black wire from the alternator because the field has residual charge in it, even if you shut the car off.

I noticed when you first start the car it isn't at 14 volts, but as soon as you rev it past 2000rpm it starts charging. Also it goes up to 14 volts and then stays there until you shut the car off.

I tested the voltage from the alternator yellow/black wire to ground, it read .01volts. I disconnect the main charging wire at the fuse box, the alternator yellow/black wire now reads 0, put the charging cable back on it reads .01 again.

Keep in mind I don't have the 4 pin plug connected to the car, its completely severed, I cut all 4 wires and am just testing voltage coming from the alternator to the yellow/black wire.

I fire up the car, test the voltage and its somewhere around .05-.3 volts, it likes to skip around, as soon as you rev past 2000rpm it goes to 3-5 volts and stays there.

So now i'm thinking, okay the main charging wire is supplying this voltage to the alternator somehow, so just disconnect the main charging wire, right?!! WRONG.

I disconnect the main charging wire at the fuse box, tape the wire off and isolate it from touching anything. Car is off, check the yellow/black wire, 0 volts, start the car, it reads .05-.3 volts again. Rev it up past 2000rpm and it reads 3-5 volts.

So now i'm clueless. Even if you disconnect the 4 pin plug and disconnect the main charging wire from the alternator to battery, that stupid yellow/black wire still gets electricity and i'm guessing that its still forcing the alternator to charge, even though the electricity isn't going anywhere because you disconnected the main charging wire.

The only way i can think of testing this is to do some MPG tests with the alternator belt off, and then with the belt on but disconnect the wires to the alternator. Compare those 2 results and see if it is in fact charging.

Back to that soft grounding of the field wire to discharge any electricity that's being generated. I tried the light bulb trick, but it didn't stop the alternator from charging, it did lower the volt output from say 14.2volts to 13.6, and when you would take the bulb off ground, it would shoot back up to 14.2 volts at the battery.

Do I need a bigger bulb or instead a resister to drain all this power? I'm afraid to play around with it, for fear of burning up some components in the alternator, and then i'm SOL. I used a test probe bulb, and also a light bulb from one of my craftsman work lights.

So frustrated........

04-08-2012, 03:08 PM	#33 (permalink)
steffen707 Master EcoModder Join Date: Oct 2009 Location: Midwest Posts: 337 Thanks: 4 Thanked 37 Times in 21 Posts	Disapointing update guys: I went out and performed a bunch of tests with the alternator on, with it in low mode, and then I shut the car off, pulled the 4 pin plug from the alternator, started up the car to do an alternator off test and my volt meter was reading 14volts..WTF!? HOW IS THIS POSSIBLE. So I remembered a thread where people said you need to soft ground the yellow/black wire from the alternator because the field has residual charge in it, even if you shut the car off. I noticed when you first start the car it isn't at 14 volts, but as soon as you rev it past 2000rpm it starts charging. Also it goes up to 14 volts and then stays there until you shut the car off. I tested the voltage from the alternator yellow/black wire to ground, it read .01volts. I disconnect the main charging wire at the fuse box, the alternator yellow/black wire now reads 0, put the charging cable back on it reads .01 again. Keep in mind I don't have the 4 pin plug connected to the car, its completely severed, I cut all 4 wires and am just testing voltage coming from the alternator to the yellow/black wire. I fire up the car, test the voltage and its somewhere around .05-.3 volts, it likes to skip around, as soon as you rev past 2000rpm it goes to 3-5 volts and stays there. So now i'm thinking, okay the main charging wire is supplying this voltage to the alternator somehow, so just disconnect the main charging wire, right?!! WRONG. I disconnect the main charging wire at the fuse box, tape the wire off and isolate it from touching anything. Car is off, check the yellow/black wire, 0 volts, start the car, it reads .05-.3 volts again. Rev it up past 2000rpm and it reads 3-5 volts. So now i'm clueless. Even if you disconnect the 4 pin plug and disconnect the main charging wire from the alternator to battery, that stupid yellow/black wire still gets electricity and i'm guessing that its still forcing the alternator to charge, even though the electricity isn't going anywhere because you disconnected the main charging wire. The only way i can think of testing this is to do some MPG tests with the alternator belt off, and then with the belt on but disconnect the wires to the alternator. Compare those 2 results and see if it is in fact charging. Back to that soft grounding of the field wire to discharge any electricity that's being generated. I tried the light bulb trick, but it didn't stop the alternator from charging, it did lower the volt output from say 14.2volts to 13.6, and when you would take the bulb off ground, it would shoot back up to 14.2 volts at the battery. Do I need a bigger bulb or instead a resister to drain all this power? I'm afraid to play around with it, for fear of burning up some components in the alternator, and then i'm SOL. I used a test probe bulb, and also a light bulb from one of my craftsman work lights. So frustrated........