lx9 generator connections...wtf

[merlot566jka]

wtf is generator turn on and generator field duty cycle signal.....

i have on my connector a brown wire for the guage/idiot light and a heavy guage power wire on the connector (red 12v) and a seperate 12v wire that bolts to the alt. i need to know how or what needs to be connected for the generator turn on and what i need to do about my indicator wire...none of this adds up.

[3100 MPFI]

According to my 1996 W-body service manual, the RED WIRE on the connector goes to the PCM to turn on the charging system.

In the 1996, the brown wire is not used. The VOLTS warning is sent from the PCM, and not the alt itself.

In my 1996 book, the RED WIRE goes to pins C16 for the CHEVY, or D2 for the buick/olds/pontiac. It does not tell me specifications for the engine itself. What year computer are you using? Which engine are you using? And which alternator are you using? I don't know RPO codes. LX9 tells me nothing, and I no offense, but I don't want to look up what engine you are dealing with. For all I know, it is a 2.8 Fiero, or a 3.4 Camaor, or a gen 1, or gen 2, or gen 3.

In my 1994 Cutlass Supreme book, it does not have a red wire at all (other than the one that is attached to the STUD). In my 1994 Cutlass Supreme book there are 2 wires. A BROWN wire that goes to a fuse in the underhood electrical center, and a BROWN/WHITE wire that goes to the CLUSTER.

In the 2 diagrams, the interior layout of the alternator is the SAME. The only difference is the WIRING.

When I compare the 2, the RED wire is the trigger from the PCM in the 1996, but in the 1994, the trigger is the BROWN/WHITE wire going to the cluster.

If you want, I can get a scan for you. For now, here is the 1994 Cutlass Supreme scan. If you want the 1996 one, let me know and I will scan it.

[merlot566jka]

ok, this is for the 3500 alt on a fiero. i am using the 1227730 ecm

i have all the wiring diagrams i can imagine (used to work for a gm dealer and have all the passwords to gm dealerworld)
yet it doesnt tell me what i want to know. i think you were getting close.

what signal is used to turn the alt on, the signal from the pcm.... and how does the ecm send alt output signal to the cluster?

i just need the alt to charge, and signal for my guages.

[IsaacHayes]

The gauges get 12v signal just from a hot wire, nothing special from the alt. Just as if it were to plug into the cig lighter to read the voltage.

[3100 MPFI]

I think it is just the OBD2 that requires the PCM to turn the alt on and off. I think the older setup it just reads voltage from the battery directly from the wire that goes from the starter to the stud. IT then automatically turns on and off.

If you look at the diagram I posted, the wire on the stud (red) has a line stating DC VOLTAGE sensing input. I think it senses from that when to turn on the alt, and when not too.

I might be way off on that, but that is how I am reading it. It was just the 1996 diagram that lists an on and off, but it is from the same wire that goes ot the gauges. I think that wire gets a signal and when it does not get power (off, or malfunction), that is what trips the light to come on (hence the grouding). Give me an hour or two, and I will scan the 1996 diagram for you.

[3100 MPFI]

I scanned a couple more diagrams. I did the 1988 AUTOMATIC and MANUAL starting and charging systems, but the only difference between the 2 is the PARK/NEUTRAL switch for the starter. The charging system is the same for both. I also grabbed the 1996 scan.

You can see that they all look the same, and are pretty much wired the same, but the 1996 lists the on/off switch for you.

Now that I look at it in more detail, it looks more like the 1996 does not really have an on/off, but the older ones do, but either way, it still looks more like it is controlled INTERNALLY. I think the PCM hookup on the 1996 is only for the GAUGE to turn on if there is a problem. Now that I REALLY think about it, even the LOW OIL light on the 3100 is signaled by the PCM.

I think that the wire (C - BROWN) in the 1994 scan worked more as the ON/OFF than the one I previously listed.

I still think that as long as you have the indicator light wire, and the main starter wire hooked up, it will internally regulate itself. Still. Maybe someone else can use these scans.

1988 Cutlass Supreme 2.8 MPFI manual transmission wiring diagram for the starting and charging system.


1996 W-body charging system.

[merlot566jka]

awesome!!! thanks taylor! i guess if i had studied them as you did would have concluded the same.

[3100 MPFI]

I have even noticed with myself that I don't always see the big picture. Sometimes I have to talk it out. I was watching TV recently and found a new hero. Someone that I REALLY relate too. His thinking is almost the same as mine, and like me has to talk it out to realize what he already knows. I am kinda like HOUSE M.D. just without the M.D. part. I am more like Dr. Vindaloo M.D./QUACK

[ForcedFirebird]

I have even noticed with myself that I don't always see the big picture. Sometimes I have to talk it out. I was watching TV recently and found a new hero. Someone that I REALLY relate too. His thinking is almost the same as mine, and like me has to talk it out to realize what he already knows. I am kinda like HOUSE M.D. just without the M.D. part. I am more like Dr. Vindaloo M.D./QUACK

I'm like Dexter

[merlot566jka]

i have no idea what you two mean by that....i assume its tv related, i dont watch much tv. never have, so i kinda dont get things like that. kinda odd when im in a large goupe of people and i dont get a joke cause its something that was on the tube. i just cant find time for tv. or sleep.

i do have to talk things out when i get tired....today when i was hooking up the lt1 tb on the 3500, i couldnt figure out the tb linkage...then my wife asked what i was up to. i then realized, after explaining to her, that the cable PULLS the tb open....it doesnt push. i fell asleep shortly afterwards halfway in the trunk, halfway on the engine.

[ForcedFirebird]

i have no idea what you two mean by that....i assume its tv related, i dont watch much tv. never have, so i kinda dont get things like that. kinda odd when im in a large goupe of people and i dont get a joke cause its something that was on the tube. i just cant find time for tv. or sleep.

i do have to talk things out when i get tired....today when i was hooking up the lt1 tb on the 3500, i couldnt figure out the tb linkage...then my wife asked what i was up to. i then realized, after explaining to her, that the cable PULLS the tb open....it doesnt push. i fell asleep shortly afterwards halfway in the trunk, halfway on the engine.

I don't watch much, but there are about two shows a week that I like to catch, Dexter is one (he's a vigalante serial killer).

Back to the ALT probelm. I remember last time I had a problem getting one to charge and it was a matter of using the on/off lead and running it to the ignition on and it had to go through a 10ohm resistor or the idiot light. The other lead was for a voltmeter, are the 3500 alternators still the same? (3 wires and a big charge wire).

[merlot566jka]

well what i found in the salvage yard was many diff alts on the 660's this is a new connector for the 3500, using only two wires but its the same connector that was used on other gm cars. i got my connector from a sunfire.
the 3500 alt uses only pins b and c of the connector. some other gms used a third terminal in there. the connector has 4 pin capability. they are all inline...like so... ∙ ∙ ∙ ∙ the ones i saw on the 3100s and 3400 were different, like so - ∙ ∙


heres my problem...i have a big red wire on my CONNECTOR. its about 10 guage. what was that for? where does it go now??

[3100 MPFI]

I think all of my cars have different wires. As for the BIG WIRE in the alt connector, that..... hmm.....

Okay. I current have my 1988 Cutlass Supreme, 1989 Cutlass Supreme, 1994 Cutlass Supreme, 1996 W-body, 1997 G-body, 1999 N-body, and 2002 W-body books on my bed, and almost all of them list something different.

The one thing that is consistant is the ones that have the big wire (either red, or orange), it goes to some sort of power supply (fuse block, fusible link).

Tomorrow, I am going to try to get over to my mothers house. I have her truck, and need to take it back to her anyways. I will take a look at my cars and see what has what, and what goes where. If I have a pic of a setup like yours, maybe I can find something out better. As of right now, all of my books say different things.

Grand Am 3400 has a RED, and a GRAY wire going to the PCM (RED is for generator terminal L monitor/control [ie dummy light] and GRAY wire is another PCM input. There is also an ORANGE wire that goes to the underhood wiring harness junction block.

I will see if I can get a better idea after checking my cars. I know one of them has the big wire.

[merlot566jka]

thanks, i have the connector with the red and gray wire...there like 18-20 guage wire.... no where close to what mine had. ill look more tomorrow...wifes getting pissy

[3100 MPFI]

RED and GRAY sounds like the 1999 Grand Am setup. I will take a look and see what I got. I will even scan the 1999 Grand Am books. It kinda makes sense that they would be similar. I believe the 3500 cars use a BCM like the Grand Am, so it only makes sense that the PCM setup would be the same.

Do you know the YEAR, MAKE, and MODEL that your engine came out of?