Slacken09

I recently bought a 1998 Camaro SS, and am a little confused over the exciter wire going to my alternator. I'm in the process of upgrading my alternator to a 145 amp truck alternator as I just upgraded my stereo. I noticed the exciter wire was not connected going to my old alternator and looked as though it had been ripped in half some time ago. I know the 98's are a little different from the 99-02 camaros, and that the exciter wire supposedly goes to the dash, as opposed to the PCM. I also read in a couple places that a resistor must be in line to knock down the voltage in the exciter wire going to the alternator. My question is, should there be juice in the exciter wire when I turn the key on, or must the car be running? Also, the alternator is out of a 03 Tahoe, and plugs right up. What pin on the alternator connector should I be aiming for when splicing in my exciter wire?

Thanks for all the help!

Slacken09

After a little research, it looks like I need to run the red wire to slot L on the actual alternator. My main concern is, should my exciter wire have power when I turn the key. I don't seem to be getting any power to it. I will look at it again later when I get time. Any idea exactly how much voltage it should be putting out?

Thanks

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iTrader: (1)

i think i posted some info in the general section about alternators.
i can only reliably tell you what i know about the 2002 model because i have the service manual for that. Calling it an exciter wire is not accurate, that is the old school way.
With an engine computer nowadays, the voltage regulator in the alternator is for the most part a microprocessor, or ASIC, and it get's a "computer signal" from the PCM.
for my 2002 it receives a turn on signal from the PCM and from memory i think it's a 5v signal, and the pcm doesn't turn on the alternator to tell it to start charging after the engine is running and the PCM sees rpm output from the crank sensor, the purpose of which is to improve idle quality and startup by not loading the engine with the alternator. but the alternator starts charging or is told to within a 1/2 second after running. newer cars get even fancier with a PWM signal to further control the alternator for fuel economy. the same sized alternator may fit multiple models and years but you take your chances with the voltage regulator being compatible with what the PCM expects.
you've probably read PLIS, the markings on the 4 terminals of the alternator. how gm or any manufacturer use them is up to them, there's no standard. in my opinion your best bet is to get a voltage regulator from your specific model/year alternator so you know it's correct then install into the alternator you want to use. i think the voltage regulators are all the same size and fit so they should interchange between alternators. and i thought i remember reading 1998 model f-bodies were different than 1999+ regarding the PCM alternator interface, but i don't know for sure. chances are if the regulator has only 1 wire to it it's a turn on signal. if it expects a 5v signal and you put system voltage of 12-14v to it chances are you'll wreck it. also later model year also send a duty cycle signal back to the pcm so the pcm can monitor and control the alternator, if you wire that to the hot side of the car's electrical system you may then have this ac frequency throughout the car which will further compound problems.

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iTrader: (1)

also the big problem with the 1 wire controlled alternators via the pcm, the voltage regulator usually shorts to ground if the regulator senses a problem internally. that's how it tells the pcm there's a problem. the pcm senses that connection to ground going to alternator which equals problem then sends a signal to the instrument cluster illuminating the battery light and check engine light.
if you run a 12v wire directly to a regulator that works this way and the alternator voltage regulator faults and grounds, then you'll blow the fuse on that 12v circuit.
the old school way was the i think the I terminal got ignition voltage which was the exciter wire, and the L terminal went to the instrument cluster warning lamp which was an actual bulb with resistance.

http://www.motor.com/article.asp?article_ID=1203

i really don't understand the hype behind this alternator upgrade mentality.
mathematically, the oem alternator puts out plenty of power up above 2000 rpm for any stereo system, and you can only put so many amps into the battery to charge it. at idle all alternators output very little including high output alternators, unless you change to a smaller pulley to spin the alternator faster. the output rating is largely bullshit because that is what it is capable of doing, not what it does under normal conditions. and usually any alternator that is run to it's rated maximum overheats and kills the rectifier. in my opinion you're better off sticking with the oem alternator, and putting your money towards a good AGM battery with high reserve capacity and a batterytender or batteryminder.