welll i drove the car open header to the muffler shop and it turned off like 2 blocks beofre i got there cAR WAS completely dead no battery then i jumped it and made it to the shop i thought i didnt have to connect a cable as long as i used the factory lt1 harness connected the right way like from factory i dont know why it wont stay running once i pull the positive off the battery the alt is a known good working alt as it came off my other car.


it says that out of the c100 bulkhead connector the BROWN wire is the one for the charging system so what do i connect to it, from the Caprice lt1 harness.

 

im not sure of the color on the lt1 wiring, but the brown wire needs to see 12V ignition to excite the internal voltage regulator in the alternator.
find out what color wire is the excite wire and get it to 12v ignition.

 

I had the same issue, just run the one wire to the alt. unlike the 3rd gen 2 wired

 

ok i got it i just used the plug from the TPI harness and it had 3 wires the fat red one went to the back of the alt one of the other ones went to a switched 12v source. now it charges.

 

thats strange I had to use the lt1 one only, all it needs is a 12v source. but all that matters is you got it working, hope it dont drain your battery now, over night

 

yeah i got it working without a problem and its not draining the battery will keep you guys posted unless it stops working...

 

well it officially stopped working the car just cut off on me when i was driving and when i went to crank it it turned over once at thats all, then i tried to give it a jump with both a jumper box and another car and it still didnt want to turn on was pretty week i had noticed that the positive cable was sorta loose on the battery so i tightened it up and tried jumping it again with another car and got it to turn on i left the car running for about 5 mins after i unhooked from the other car and then the car just turned off by itself when i went to turn it on again NO GO!! it did the same 1 time over only, my thoughts are they alt is or wasnt any good in the 1st place so i am heading to the auto parts to check it out on there machine .


i currently have the alt plug wired up like the following i used the 3 wire plug that was originally from the TPI motor and connected the FAT RED wire to the constant power on the back of the alt which comes from the battery then i pulled one of the other wires from the same plug to a 12v switched source then the other brown wire i just left it unconnected as there is no power coming out of it, why does it not charge with the normal plug coming from the caprice harness, the way i had itconnected above worked for a couple days and i put the machine on it and it said it was charging with all accesories on but when i disconnected the positive off the battery while it was running the car still didnt want to stay running it just cut off where as other cars you disconnect it and the car stays running with the ALT only why wont it do that here?

someone please help me as i am getting really frustrated i want to do it right but dont understand why it doesnt charge with the original plug from the harness nonetheless with the rig i did with the TPI original plug whats the deal this cant be that hard to do......

 

Ok

Most GM alternators are pretty simple... one big screw terminal on the back goes directly to the batt+ (thick cable) the other Voltage Sens wire SHOULD go to the FUSE PANEL...

ALL of the 1 wire Alternators are garbage.. basically what they do is output a set votage which is OK for most street rods... but... the reason the SENS wire should/NEEDS to go to the fuse panel+ BATT+ connection is that the alternator reads the FUSE PANEL voltage and tries to keep that at a consistent ~13v... that means the alternator might put out 14.5 or 15v measured from the back of it but what it's doing is measuring the "SYSTEM" voltage/PCM voltage and the regutlators are constantly adjusting output to meet the FUSE PANEL/PCM power to keep it where it needs to be REGARDLESS of what the output of the alternator readss..

SO... if you see a bunch of older cars with ONE WIRE alternators running around with dim headlights this is exactly why... becuase the alternator SENS wire is simply connected internally to the output terminal and not to the fuse block/headlights... PCM... Fuel Pump.. everything else is getting ~11-12v due to the power lost in the main line feeding the fuse panel.

Now.. some GM alternators require a dash light to be connected to one of the alternator wires simply to assist in the power sensing... but that depends what alternator you have... if you have it connected direct (without the light) you may experience a dead battery the next day since the alternator never really "shuts off/disconnects".

IF your alternator is not charging... I would (WHILE RUNNING):
1) Check voltage at the output prong (main output wire going to batt). Normally Power is over 12v when idle... anything less you have a problem. Check power at the batt... at the back of alt they should be the ~same.. if not you found your problem-fix connection
2) WHILE RUNNING take the SENS wire and touch it to the + terminal on batt.. you might hear the motor die down or alternator start to whine.. this is GOOD! Next would be take that wire and hard wire it directly to the FUSE PANEL BATT+ terminal... you should hear the same Alt. Whine as you did when connected directly to the Batt+... maybe even worse since the voltage reading at the Fuse panel will be less than the Batt+ so it will have to work harder to raise power where it needs to be.
3) If you tried all this and cant get it to work or it works intermittently, you problably have a bad alternator.

Pretty much the alternator tries to keep a set voltage at the fuse panel.. if you use 1 wire alternator that is only keeping set voltage at the alternator, that means at least 1v drop under load from Alt to Fuse.

 

One other MAIN point.. when alternator is working you should read from 12.5-14.5v inside car or with the gauge...

When alternator cuts out voltage usually drops to under 12.5v pretty quick, but car usually runs until under ~11v...

Your describing a car the just suddenly dies then dead battery... just wanted to clarify the batt stores enough power to keep it running for a while but eventually the power hits a level where it just cant keep up... that is usually under 10v... that's usually caused from the Alt not charging for a long while.. not suddenly

 

i disagree about the wire wire alternator comment.
if your lights are dim, its either too small of a charging wire, not enough amp on the alt, or an incorrect pulley system for the application. there are several different voltage regulators as well, so yes. dim headlights are possible with a mis matched combo.

i can say that if its an option for you, a local starter and alternator shop can convert pretty much any alternator to a "one wire" set up if you choose.
its usually around 80 bucks, depending on the alternator.

good luck. replied to your pm.

 

well just got back from the auto parts they checked the alt out and it works perfectly so its not the alt. icharged the battery and it took charge with no problem and the car turns over and on quickly so its not my red top optima so it has to be in the way i wired it up, my question is why is it that the 2 wire plug which both wires are brown how come there is no signal coming from either wire also why does it not just charge with the harness alt plug the plug i have in there now is the TPI plug and it has 3 wires coming out of it 1 red wire and 2 smaller gauge wires what do i need to do with thes to make this thing charge...

and can someone answer the ? of if the alt is truely charging if you disconnect the positive wire on the battery the car SHOULD STAY RUNNING this what i have rememebered from previous alt altercations.

please help me guys i need to go on a trip with this car by sunday and i nee to wire this thing up correctly in order to get there man this sucks well at least i didnt have to buy a new alt.

 

read my above posts. just make a test lead on the small wires to the battery to see which wire excites the alt and then you can wire it up properly after a test.

also, those plugs wear out in a hurry. look at the plug and see if the pins inside have a small hole, or are opened up all the way. the lil wires may not be making contact from the plug to the alt.
you can close up the female ends inside the plug using a very small flat blade screwdriver, or a small punch.
id recommend doing that anyway.
good luck.

 

allright i bought a new plug from the auto parts and it has 3 wires on it also i will see which of the small wires excite the alt. and brings the motor down at idle when i connect it, so i just connect it to the positve on the battery one of the smaller wires then i will go outside and try it now. once i find the wire do i just leave it connected directly to the battery? also wont it be the same if i connect it to the rear of the alt to the large alt feed wire which comes from the battery regardless?

also is the car supposed to stay running when you disconnect the power wire from the battery i was under the impression that it does stay running as this is a 140amp alt that it has on it, please get back and let me know i am going outside and trying it out now....

thanks for the help once more...

 

I used the stock wire on the LT1 harness, put the one red wire from the white plug on the LT1 harness to a 12v switched source with a 480ohm 1w resistor inline (this is needed to keep from burning the alt up) and has been charging for over 2 years now no problems at all.

 

well i found out that my 1 ground wire was not enough i connected 2 more ground wires thick ones to the battery and WALA it starts....with no problems i was experiencing a hard start because of the lack of ground. i got the alt charging like this now and it reads above 13V just a little with lights fans and everything on WOOT WOOT.... i had noticed this becasue the alt was charging when i put the tester on it and the battery had 13v of chaRGE out of the 3 wires coming out of the alt the fat red one and black thin wire went to a 12v switched source then the brown wire this is going to sound funny but this is how i did it i conected it to a light bulb the brown wire going into the bulb on one side then the other wire coming out the other side of the bulb goes also to a switched 12v source to what ends up happening is that when th key is turned on the light comes on of course but when the car is on and running the light is off if the light comes on then the ALT has stopped charging if its OFF then the ALT is charging with no problems this is to act like a dash lamp would to let you know when car is charging....i finally figured it out and now with the xtra grounds in place and battery fully charged and the alt wired up correctly now is the 1st time i see the volts guage inside read above 13v with all accesorries on this is great i left the car running for about 30mins at idle and turned it off when i went to turn it on WOOT WOOT started like a champ with no delay or hard start. the fans actually sound like they are blowing harder now nbelivable this electricity stuff i think its time for me to take some classes in electricity.

 

Hmm....mine is 14.1 volts with lights on.....

 

i am going by the stock guage which really doesnt telly you to much detail if you know what i mean i havent hooked up a scanmaster or any other type of diagnostic device to see where it would be at exactly and no i dont have an aftermarket volts guage either.

so 13.5 or more could be possible.

 

did you put the small wires to switched 12v? if you run them straight power, the alternator will drain your battery with the car off.
you last post was kinda confusiing with the bulb.

 

all 3 wires are going to a switched 12v source.