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Discussion Starter #1
i now have the my new vortec 350 up and running in my jeep however the alt. isn't charging. i have had it tested and it is good. i put another alt. on and it didn't charge either, i have made sure the eng is grounded to the frame and the eng. to the body and nothing. the only two wires to this alt. (99 gm) are the lead to the battery and the exciter wire whick is recieving voltage. i am lost! if the exciter wire is feeding voltage then the alt. should be creating voltage right??? my wife has a 99 tahoe with the same motor and everything is the same. just two wires the batt. charge wire and the exciter wire. there is one difference i have found. if it is running and i put the negative lead of my m/meter to the neg. post on the battery and the positve lead to the alt. housing mine reads .007-.009 vdc and when i checked the one on my wifes it had like -.014 vdc. i am supposed to be going to clayton this coming weekend and i can't figure this out. i have gone over and over it. any help would be greatly appreciated!!!
 

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Sounds like something is open in the gound circuit, when you check the ground path are you using the ohms scale or vdc? The proper method is to use vdc to check for leakage. I assume the battery is good and will take a charge, sometimes they use fuseable links in the circuits and this throws things out and for a loop. The stuff I would check is ground path to the alternator, I have my engine block grounded to the battery and to the frame, then the body...is the pulley the correct size? Just throwing out idea's here...
 

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ther is Nothing Else in the Puzzle it should Be charging???? i have read Everything you said,,, And Did you Check the Sepentine Belt??

Maybe Slipping ???

Too wierd I would check the Excitor Wire again for Full 12 Volts !! at time of running engine Thats All there Is In the Charging Sytem you have a Stand Alone Engine Harness Correct!

pretty weird 2 Alt Same thing!

Adam,
 

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update: i said before that i stole the alt. from my wifes 99'tahoe with the same motor and put it on and it worked!! like i said earlier the one that came on the eng. didn't work yet it tested good on the bench. i borrowed a new one from my buddy's napa store to see if it would work and nothing. well i was messing with it and decided to sneek the wifes just to try and it worked. well i took it for a short spin around the yard and pulled it back in the garage to finish cutting the floor to clear the x-case shifter so i could put it in 2wd high. i did and when i was done i pulled it back out and was pulling down the drive way when i could hear my elec. fans surging. if i gave it gas the voltage would increase from 14volts to like 16-18. well i stopped and then the guage suddenly went to 12volts and started slowly decreasing so i pulled it back in the garage. i still get voltage to the exciter wire connector. i seem to have fried the wifes alt. !!!! oh boy i can't wait till she wakes up and hears about this! anyway any new clues from this info? yes the belt and pulley are good.
 

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You have A short in You'r Harness Some Where This happened to me on the trail andOne Of my rock Lights Was Grounding on the frame And it would Ocasionally Hit And My alt Gauge would go Wacky and Start To over charge And then The Light would get very Bright and Then It would Go away!! check You'r Harness!!

this is what I would say
 

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My money is on a bad connection/broken wire, most likely the charge wire. Disconnect it at both ends, (Battery end and Alt end) and put an ohm meter on it. Then start moveing things around. I bet you find something that breaks the circuit.
And your wife's alternator is probably fine....Just got dropped out of the circuit. There isn't anything there that should blow it, unless you have a direct short. Sounds more like a broken circuit than a shorted one. You would have blown your fusible link.....You do have a fusible link, don't you? <IMG SRC="smilies/biggrin.gif" border="0"> <IMG SRC="smilies/bounce.gif" border="0"> <IMG SRC="smilies/bounce2.gif" border="0"> <IMG SRC="smilies/biggrin.gif" border="0">
Good Luck!
 

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Discussion Starter #7
well i really don't think it is the charge wire because i have continuity and the hot post doesn't put anything out when it is running. i'm kinda lost here. i have everything grounded but i'm still not sure why on the tahoe if i put the neg. lead to the neg. post on the bat and the pos. lead on the alt housing it says -.014 vdc and if i do the same to the jeep it says +.009 volts? i have to work tonight so i have to get a couple hours of sleep and i am not too
happy about all of this. my jeep has been down for 4 mo. now and i was supposed to go wheeling this weekend and this looks like it is gonna prevent me from going if i don't figure it out soon. <IMG SRC="smilies/crybaby2.gif" border="0"> <IMG SRC="smilies/crybaby2.gif" border="0">
 

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Try running a jumper from the charge terminal to the battery positive post. If you get voltage, then it is wire/connection. With the engine running, if the charge wire is intact, even if the alt is not charging, you should have battery voltage (12.5V) at the terminal on the alt. If you don't you have a bad connection to the battery. You will get bogus readings at the charge terminal if there is no connection to the battery, because the voltage regulator works by sensing that voltage.....The voltage regulator doesn't know what to do when there is none. Good Luck.
 

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Discussion Starter #9
Originally posted by 4wheeldog:
<STRONG>Try running a jumper from the charge terminal to the battery positive post. If you get voltage, then it is wire/connection. With the engine running, if the charge wire is intact, even if the alt is not charging, you should have battery voltage (12.5V) at the terminal on the alt. If you don't you have a bad connection to the battery. You will get bogus readings at the charge terminal if there is no connection to the battery, because the voltage regulator works by sensing that voltage.....The voltage regulator doesn't know what to do when there is none. Good Luck.</STRONG>
i do have battery voltage at the charge terminal on the alt. i also have continuity through the cable running to the battery. the exciter wire feeds voltage all the way to the connector and that is the only two wires to the thing. everything checks the way it is supposed to except for this. i'll try the jumper when i get home in the morning but being that when the one alt. was working for the short period of time it was feeding the battery and the fact that it has continuity i really don't think that it is the cable. can't hut to try. i am running out of things to try. it all checks out the way it is supposed too!!!!! <IMG SRC="smilies/pissed.gif" border="0">
 

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Yes, I realize this thread is really old. Hi5 did you ever figure this out? I have the same problem. running the stock harness straight off the donor. '97 350. drains the battery then won't run anymore, alt doesn't want to charge it.
 

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Discussion Starter #11
Andy 911 said:
Yes, I realize this thread is really old. Hi5 did you ever figure this out? I have the same problem. running the stock harness straight off the donor. '97 350. drains the battery then won't run anymore, alt doesn't want to charge it.
you have to run a light inline with the exciter wire or it will not work. i have also heard a 150 ohm resistor works but i have not tried it. mount a light on your dash and use it as your charge indicator lamp.
 
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