Alternator plug wiring issue
I'd like to correct a few things that have been posted in this thread...
IN OUR CARS (i.e. the OP's 1998 TransAm), the one wire in the alternator plug is the exciter wire that runs from the alternator (harness) to the PCM. The wire goes in the second spot closest to the driver side (third one from the motor) when it's plugged into the alternator correctly. (Edit - Posted a pic below)...
This wire lets the PCM tell the alternator how much amperage to provide. The factory wire coming from the wiring harness is a very thin dark red wire (when it gets dirty it may look brown). It's easily snapped when removing the alternator, which is why it's somewhat common to see aftermarket replacement wiring harnesses. The aftermarket harnesses are normally generic and come with all four wires, even though you only need the one.
The other three wires in the harness are not needed (the factory plug does not come with them) and can be removed from the aftermarket connector plug, they do not connect to anything in the car.
IN OUR CARS, NONE OF THE WIRES FROM THE ALTERNATOR HAVE ANYTHING TO DO WITH THE DASH, lights or otherwise. The PCM sends the signal to the console/gauges, there is no direct connection from the alternator to the gauges/console.
"Volts bouncing all over" symptoms are usually either due to faulty wiring or a bad voltage regulator (which is inside the alternator on our cars). Swap the alternator and fix the wiring and see if your problems go away.
Rob (Bad30th)
IN OUR CARS (i.e. the OP's 1998 TransAm), the one wire in the alternator plug is the exciter wire that runs from the alternator (harness) to the PCM. The wire goes in the second spot closest to the driver side (third one from the motor) when it's plugged into the alternator correctly. (Edit - Posted a pic below)...
This wire lets the PCM tell the alternator how much amperage to provide. The factory wire coming from the wiring harness is a very thin dark red wire (when it gets dirty it may look brown). It's easily snapped when removing the alternator, which is why it's somewhat common to see aftermarket replacement wiring harnesses. The aftermarket harnesses are normally generic and come with all four wires, even though you only need the one.
The other three wires in the harness are not needed (the factory plug does not come with them) and can be removed from the aftermarket connector plug, they do not connect to anything in the car.
IN OUR CARS, NONE OF THE WIRES FROM THE ALTERNATOR HAVE ANYTHING TO DO WITH THE DASH, lights or otherwise. The PCM sends the signal to the console/gauges, there is no direct connection from the alternator to the gauges/console.
"Volts bouncing all over" symptoms are usually either due to faulty wiring or a bad voltage regulator (which is inside the alternator on our cars). Swap the alternator and fix the wiring and see if your problems go away.
Rob (Bad30th)
What you described (wire going to PCM) is only on 99-02.
Having said this, on my 98 formula I too am having voltage problems. (Not to Hijack this post)... but my problem is a little different. I actually replaced a bad alternator but in the process of installing I snapped the excitor wire un-benounced to me. So, when I fired up the car of course the volts automatically showed low voltage. I took it around the block to see if it would bring the volts back up and when it didnt, I was afraid to drive any further. I thought " Well, I bought a faulty alt" and began to uninstall it. Thats when I realized that I had snapped the wire. Just for good measure, I took the Alt. down the street to my local part shop and got it tested and it was fine. I ordered a replacement plug for my alternator. Now, here is my question... Is there a way to test that excitor wire? Keep in mind this is a 98. I really dont want to install the plug and the alternator just find out this is not really the problem. Right now my car sits without an alternator and an exposed wire. I tried a test light on the wire while I started the car, but it doesnt light up. Is it supposed to? Or was the Alt. actually working and I didnt know it was because I had snapped the wire to my gauges. Does this make sense? TIA
Having said this, on my 98 formula I too am having voltage problems. (Not to Hijack this post)... but my problem is a little different. I actually replaced a bad alternator but in the process of installing I snapped the excitor wire un-benounced to me. So, when I fired up the car of course the volts automatically showed low voltage. I took it around the block to see if it would bring the volts back up and when it didnt, I was afraid to drive any further. I thought " Well, I bought a faulty alt" and began to uninstall it. Thats when I realized that I had snapped the wire. Just for good measure, I took the Alt. down the street to my local part shop and got it tested and it was fine. I ordered a replacement plug for my alternator. Now, here is my question... Is there a way to test that excitor wire? Keep in mind this is a 98. I really dont want to install the plug and the alternator just find out this is not really the problem. Right now my car sits without an alternator and an exposed wire. I tried a test light on the wire while I started the car, but it doesnt light up. Is it supposed to? Or was the Alt. actually working and I didnt know it was because I had snapped the wire to my gauges. Does this make sense? TIA
Banned
Joined: Sep 2010
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Just yesterday on my 99 T/A WS6 my alternator went out, right before it went out the lights were pulsating enough for me to notice while driving at night. I went to take out the alternator once i noticed the gauge wasn't showing that my battery was charging. I got the alternator out after about an hr and didn't realize until i got it to the the part store to test it that i had ripped the excitor wire out of the clip. The alternator failed the test and i bought a new one. I then took it back home and thought i would be able to install it, without worry about the excitor wire...WRONG. I installed it, started it up and before i knew it my car was just trying to idol because the battery did not have enough power to run the necessary components to keep it idling. So i took out the alternator and now i am trying to fix the excitor wire. Problem is there is not enough wire exposed on the clip because it ripped so close to the connector. I am going to try and take apart the connector and sauder some wire on to it so i will be able to splice it in. Does anyone know much about these clips and how easy this is to do? To answer the previous posts questions, i'm pretty sure without the exciter wire your battery will not get a charge because the alternator is not getting a signal that tells it to charge.
Once you have the plug taken out, you need a special tool to get the wire and terminal out so you can work on it. The tool is very simple - it looks like a small pointy flat screwdriver. If you google "metri-pack 150" you will find some links that give you a good idea of what you're working with (that's the series connector it is.)
If you get it apart, take a picture of the terminal/seal/wire assembly and I'll send you one. The parts cost pennies... I'll spend more buying the stamp!
If you get it apart, take a picture of the terminal/seal/wire assembly and I'll send you one. The parts cost pennies... I'll spend more buying the stamp!
Just yesterday on my 99 T/A WS6 my alternator went out, right before it went out the lights were pulsating enough for me to notice while driving at night. I went to take out the alternator once i noticed the gauge wasn't showing that my battery was charging. I got the alternator out after about an hr and didn't realize until i got it to the the part store to test it that i had ripped the excitor wire out of the clip. The alternator failed the test and i bought a new one. I then took it back home and thought i would be able to install it, without worry about the excitor wire...WRONG. I installed it, started it up and before i knew it my car was just trying to idol because the battery did not have enough power to run the necessary components to keep it idling. So i took out the alternator and now i am trying to fix the excitor wire. Problem is there is not enough wire exposed on the clip because it ripped so close to the connector. I am going to try and take apart the connector and sauder some wire on to it so i will be able to splice it in. Does anyone know much about these clips and how easy this is to do? To answer the previous posts questions, i'm pretty sure without the exciter wire your battery will not get a charge because the alternator is not getting a signal that tells it to charge.
Just yesterday on my 99 T/A WS6 my alternator went out, right before it went out the lights were pulsating enough for me to notice while driving at night. I went to take out the alternator once i noticed the gauge wasn't showing that my battery was charging. I got the alternator out after about an hr and didn't realize until i got it to the the part store to test it that i had ripped the excitor wire out of the clip. The alternator failed the test and i bought a new one. I then took it back home and thought i would be able to install it, without worry about the excitor wire...WRONG. I installed it, started it up and before i knew it my car was just trying to idol because the battery did not have enough power to run the necessary components to keep it idling. So i took out the alternator and now i am trying to fix the excitor wire. Problem is there is not enough wire exposed on the clip because it ripped so close to the connector. I am going to try and take apart the connector and sauder some wire on to it so i will be able to splice it in. Does anyone know much about these clips and how easy this is to do? To answer the previous posts questions, i'm pretty sure without the exciter wire your battery will not get a charge because the alternator is not getting a signal that tells it to charge.
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Joined: Sep 2010
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Well i fixed my T/A last night. I repaired the broken clip without buying a new one. I was able to get a small enough flat head screw driver and push it down the opening on the front end of the clip. It took me a couple times before the metal connector with the wire crimped in it came out. I soddered on some 18 guage wire which was alittle bigger than the original wire. I then reassembled the piece. Next i had to Solder the broken clip with the extended wire to the wire on the car, this was the hardest part because there is not much room to sauder underneath the car. After about 15 mins i was able to solder and wrap the connection with electric tape. I reinstalled the alternator. Only thing i forgot was the rubber spacer on the clip before i realized it was on the garage floor. So i straigtened out a wire hanger and hooked the end. Opened the hood and fished the clip off. Put the rubber spacer on and cliped it back on from the underside of the car. My lights stoped pulsating and my car is running fine. Have to say i don't wanna do that anytime soon again.
Teching In
Joined: May 2007
Posts: 27
Likes: 1
Hate to reup an old thread... but this is precisely what i'm dealing with right now.
does anyone have any definitive answers about this excitor wire?
I have a 2000 Camaro SS. the wire snapped off RIGHT NEXT TO THE PLUG... there is no chance at sodering it back. and as everyone knows, the alternator process on these cars is a huge beach. so i dont wanna put it on, and not be able to get the wire plugged in if its necessary.
so does it give information to the alternator, or is it simply an output for the dash?
From another small NJ carclub F body forum:
does anyone have any definitive answers about this excitor wire?
I have a 2000 Camaro SS. the wire snapped off RIGHT NEXT TO THE PLUG... there is no chance at sodering it back. and as everyone knows, the alternator process on these cars is a huge beach. so i dont wanna put it on, and not be able to get the wire plugged in if its necessary.
so does it give information to the alternator, or is it simply an output for the dash?
From another small NJ carclub F body forum:
Last edited by Noodles; Mar 3, 2011 at 02:47 PM.
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