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New guy with problem (already)

Papi Grande

Papi Grande

1/2 ton status
Joined
Aug 20, 2008
Posts
413
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Location
Krum, TX
Hey guys...just got my membership and need help already!!..I've read you guys' comments for a while now...lots of good info...first a little about me...recently got out of the Army-4th Infantry-Ft. Hood, TX (9 1/2 year diesel mech./paratrooper), I now work in the oilfield on wellheads in the Barnett Shale(Ft. Worth, TX) and love it!!! I traded a yamaha banshee for my current project...I actually wanted a military HUMVEE but couldn't afford it...so my 85 K5 Blazer is the closest I could get(for now)...It has a 6.2 diesel w/ a turbo from a 6.5, serp. belt system off of a 96 6.5, 5" lift, 37" HUMVEE tires, custom 4"(no muffler) exhaust...this truck was a basket case when I got it...but I love working on it...anyway my problem is this....when I put the serp. belt system on, I used the alternator from the 96...but i can't fgure out how to wire it into my existing wiring harness in order to make it charge...the old alt. had the two pronge plug and the battery lug on the back...the 96 alt has a 4 prong plug w/ battery lug on the back...has anyone on here been able to figure how to get the newer alt. to work with the old wiring harness?...if so I would appreciate a little advice...thank you guys for the help already and nice to meet all of you!!!...Also if anyone lives close by let me know so we can do a little mechanical hiking!!!!:D
 
Actually really easy! AC-Delco makes a wiring harness adapter to convert from your old SI alternator to a new CS alternator like the 6.5L would have. Its actually a major upgrade too, your headlights will be brighter at an idle, and your wipers will be faster too. You're basically going from a 63 amp alternator to a 105 amp alternator.

So, slap that thick power wire back onto the rear post of the new alternator, then the next part depends on if you have an alternator idiot light, or if you have a volt gauge.

If you've got an idiot light, you need to buy AC-Delco part number 8077, if you have a volt gauge, you need to buy AC-Delco part number 8078.

The difference between the two has to do with the resistance on the brown wire coming from the 4 pin connector on the new CS alternator. From the factory, all trucks and cars with those specific alternators have an idiot light for the alternator. That idiot light bulb is basically just a 75 ohm 3 watt resistor, or somewhere within that ball park. The alternator depends on that resistance being present to drop the voltage on the brown wire going into the alternator.

If your truck does not have the idiot light, it will simply be feeding 12 volts into the alternator, which will kill it in a real hurry. The second adapter for the trucks with volt gauges has a built in resistor that acts as the missing light bulb in the factory vehicles.
 
Thank you both for the good info...I am a wiring Dee-dee-dee so i'll probably go with the little harness...I'll try and take some pics when I get the parts in...thank you.
 
ok...I have a 96 alt....so I pulled it off and looked at the plug...it is not like the end of te 8078 wiring harness...mine is skinnier and rounded on the ends...I was thinking about getting the 8078 harness and splicing the end of it to te plug of my style alternator..will this work or can I somehoe splice mine and make it work? thank y'all for your help.
 
Ah, 96 would be a newer alternator than the CS alternators too... I'll need to pop online and see what I can find for info about hooking those newer yet alternators up...
 
ok so I did a little research today and found out the my alternator is a CS130D...found a little bit of stuff, but nothig about converting it to an old style wiring harness on an old 1985 blazer...went to the garage and looked at my harness...the brown wire that goes to the alt gauge is reading 12 volts..is this right?...also I have two red wires that get plugged into the old alternator...one has .453 volts with the key on and the other has NADA...is this right?...and then there is a wire that goes from the battery directly to the lug on the back off the alternator...is this right....i'm asking these questions because when I recieved the truck my buddy made a half-a** attempt to make this conversion work and it was a basket case ...any help on how to hook these two up and make it work would be appreciated...thank y'all
 
just found this on a toyota offroad sight...does this sound right to you guys...

Now for the wiring part of this install. On the back of the alternator where the harness plugs in there should be 4 letters(S,F/I,L,P). You only need to use S and F/I. On the old round harness that plugged into the old stocker there are 3 wires, one is a constant 12v or signal and you connect that to the "S" wire on the new harness. One wire is noticeably smaller and that runs to your idiot light. Connect that wire to a 12V switched power source (not the wire right next to it!) Then you have a switched 12v source left and you connect that to the F/I wire. This one is the most important since it tells the alternator to start charging.
Now take your new 10 gauge wire and run that from the post on the back straight to the battery. At this point you might want to remove the old post wire. That can be done easily by tracing it up to the little black box it runs into and unbolting it. You'll know what I mean when you open that box.
 
Finally got it working...probably could have done it sooner if I weren't a deedeedee when it comes to electrical....this was so easy that when I did get it going I was pissed that I didn't figure it out myself....if any of you need help with one of these let me know...take care
 
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