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Electrical charging problem??

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Old May 20, 2006 | 02:42 PM
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Default Electrical charging problem??

I pulled off my alternator last week to install motor mounts. Now my battery gauge reads a bit lower than 13 volts which it used to not do. The strange thing is that when I measure voltage at either the batter terminals or the power post for the fuse distribution block I get about 12.8 Volts with the multimeter. This is with the AC on full blast and my nitrous bottle heater running. 12.8 Volts seems like a good voltage to have with everyhting running so I am thinking that the gauge is giving me scewed readings. When I pulled the alternator the first time I ripped out that little wire on the top but I went to the dealer and got a new connector and wire so that should be all good now.

Does the battery dash gauge get its power signal from that little wire on top of the alternator or what? What exactly is this little wire for anyway? I am thinking that the little wire is having something to do with this.
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Old May 21, 2006 | 12:34 AM
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it should be running over 14....like ive said to other guys to check ur alternator, u can take the battery cables off and if ur car dies then u know ur alternators screwd
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Old May 21, 2006 | 08:54 AM
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Heres the schematic for the generator. It may help you with where what goes.
Attached Thumbnails Electrical charging problem??-generator-schmatics.gif  
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Old May 21, 2006 | 12:10 PM
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Does anyone know what the voltage on the exciter wire that goes from the PCm to the alternator should be?? I am getting 10.5 Volts across it and I think its what is causing my alternator to be running a little lower than usual. I think if it had 12 V on the exciter the alternator would be fully charging. I may just go out and jump a ignition switched 12V source on the exciter wire and see if it makes the alternator fully charge.
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Old May 21, 2006 | 12:14 PM
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Originally Posted by staringback05
it should be running over 14....like ive said to other guys to check ur alternator, u can take the battery cables off and if ur car dies then u know ur alternators screwd
The alternator itself I am sure is OK, it is that the exciter wire is only feeding 10.5 V to the alternator to excite it which will cause the alternator to not put out full charge. The alternator is generating electric, just not enough due to the low exciter voltage.
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Old May 22, 2006 | 07:02 PM
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im having the same problem with my camaro...and I also beleive it is because of that exciter wire. I was changing my alternator and ripped that thing out of the back of it.

I soldered it back in the holder but the alt guage only shows above 13 half of the time. and my battery died today while I was driving.
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Old May 22, 2006 | 08:02 PM
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It wound up being the alternator after all. All is good again.
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Old May 22, 2006 | 08:02 PM
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It wound up being the alternator after all. All is good again. What was happening was that once the alternator got hot it wasnt able to keep up fully charging.
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