i just upgraded my 69s wiring harness to a internal reg alt and moved it to the pside of the motor, 73+ style.

while removeing the old alt harness i have to remaining thingies that i cant identify. they are in the upper right hand corner on the fire wall and were wired in with the alt harness, they are about 1.5" x .75" and are black plastic, they are connected and mounted on one piece of sheet metal. i have a pic but cant post.

the other thing is that i have power to every thing in the truck BUT the head lights, all marker and brake light work, key starts it, it is charging the batt, so??????

Here is a link to a wiring diagram for your engine compartment http://www.geocities.com/chevroletc1070/v8engcomp.html.

You need to put back in whatever you took out. When you switch to a int reg. alt. you should just remove the ext regulator box (its a 3 inch square box with a four prong flat plug under it on the drivers side core support) and tape the plug into your harness it wont hurt anything. When you install the new int alt. it will need a wire from the post on the back to the positive side of the battery (note should be at least 10 gauge). A second wire will be needed to excite the regulator ie: turn it on this where should be key switched hot to the plug in the side of the alt ( its probably the pink or blue wire if you got a stock plug with the alt otherwise its probably marked batt or + on the alternator) .
To check to see if your current setup is charging use a multimeter to check across the terminals of your battery with the truck running should be at least 14 volt. A no charge would be whatever your batt is without the truck running probably about 12.3 volts.

I did this from memory so if something doesn't seem right I will go scrounge up an alt. in my shop to check the connections.

GL Wheel

the way i did it i am able to 100% eliminate the external reg box, re-route the main alt wire, and ran the brown wire back into the fire wall plug like it was before.

the excite now comes from the alt itself and dirrectly back into the 2 prong plug on the alt.

i have a color version of the diamgram and neither yours or mine has the thingies labeled or even on the dia.

i know how to patch it all in before but i really wanted all of that crap out of there.

so again wtf are the black thingies???

I did not think the newer alt could self excite. This is out of my auto repair book. "Factory alternators don't have a permanent magnet as part of their field windings, therefore they will not self-excite. That is no matter how fast you spin the alt it will not produce power untill the field is energized by an outside voltage source". Unless its the one wire version. they have permanent magnets and are internally regulated.

send me the pic i will post it for you.

its not "self excite" persay a 1 wire alt, but the main power wire that runs to the battery and acces. also goes to the 2 prong excite plug to externaly excite the alt.


ill send 2 pics to your email later today.

The big wire goes to battery, the other two in the plug. one goes to battery also and the other is for the light on the dash panel.

send me the pic i will post it for you.
I will also for you.

Think but I am not sure the two plastic thingies are probably headlight relays. Could be way wrong on that though.

About the alternator. There are two versions of the two prong spade terminal 10si GM alternator. (Lot more,but...) There are one wire and external exciting units. You will have to look inside the area were the spade terminals are. If you can see a wire wound resistor on top of the regulator/brusholder (white pieces the spade terminals stick out of) it is the factory style external exciting alternator. It will require a battery sense wire to the number 2 prong (furthest from battery stud) and a light circuit wire to the number one terminal (closest to battery stud). The sense circuit has to read exactly battery voltage and can be looped to the battery stud. The light circuit wire was to come on and off with the key.

If there is no resistor you have a one wire alternator. means it only needs to be connected to the battery and spun to charge. Residual magnetism in the rotor creats a small field that the regulator senses and then turns itself on. You CANNOT hook up constant voltage to the spade terminals as it will leave your alternator turned on permanently. You can however hook the light circuit wire upto the number one terminal and it will make the alternator turn on a lot faster.

Other option for futrue reference :) is call us and we can hook you up with one wire alternators that have a lot of advantages over the older 10si series alternators.

"About the alternator. There are two versions of the two prong spade terminal 10si GM alternator. (Lot more,but...) There are one wire and external exciting units. You will have to look inside the area were the spade terminals are. If you can see a wire wound resistor on top of the regulator/brusholder (white pieces the spade terminals stick out of) it is the factory style external exciting alternator. It will require a battery sense wire to the number 2 prong (furthest from battery stud) and a light circuit wire to the number one terminal (closest to battery stud). The sense circuit has to read exactly battery voltage and can be looped to the battery stud. The light circuit wire was to come on and off with the key. "

Merace19 "The big wire goes to battery, the other two in the plug. one goes to battery also and the other is for the light on the dash panel. "

that is how i did it.

i understand the difference between int/ext alts, the alt is running and charging the truck, its all good.

the relays are not in any way hooked to anything but the alt harness, they are not a/c relays as it is a heater only cab, and not headlight relays , i solved the no head lights with a new dimmer switch.

i sent some pics to Merace19 he should have them up soon.

I have not got them. Send them to merace19@aol.com i'll post them up.

Sounds like all is good.