Z3PR
Banned
My first job was rebuilding alts and startersat a small shop. We built many high output alts. Anymore if I need a big alt, I just rebuild the one I have with the high output stator and rotor. Kits are cheap and very easy too install.
CK5
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Troubleshooting 140amp alternator upgrade
- Thread starter RootBreaker
- Start date
Z3PR said:
ok so what do I need?
I believe my alt is discharging my battery so someone said... diode kit... then what else?
I may just go out and buy a 80amp factory one... can get one for like $60 through a friend....
79Jimmy
1/2 ton status
Please read the previous posts....
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
RED and BROWN
79Jimmy said:
thanks for the clarity... but what does red and brown have to do with it?????
I basically used the acdelco wire kit (the one that has resistance) and it uses the red and brown.... that didnt work... so then i used the replacement pigtail..... put red to red and black to black.. then last night.. I put red to red and black to brown..... still no go....
even though autozone said the alt was good... how can I test it myself?
if the pulley is what actuates it... can I put a meter from ground to the pin in the back to get voltage reading or what????
Thanks...
Sincerely a frustrated and tired
Jeff
Last edited:
mouse
1/2 ton status
Is it possible that a fuse or fusible link blew when you tried to run it? I would have a quick look around. BTW, I waiting for the end of this story before I procede with my own swap!
mouse said:
That is why today I am going to do one of two things...
1. put original back in
or
2. follow mrk5's recommendation of running all new wires and use my ac delco plug...
will see tonight.. im getting good at this so may just put old one in and fire the truck up... verify charging still works... if it does.. dunno..
if doesnt.. then look for a link or something and replace wires.....
79Jimmy
1/2 ton status
Well lets assume the alt. is good and check the wiring. The main bat. cable bolted to the back should show +12VDC, again referencing your diagram the #2 wire of the 2-wire plug-in should also show +12VDC all the time, the #1 wire should only show +12VDC when the ignition is in the run position. If these conditions are not met the alt. won't charge. I would first look at the fusable links up on the firewall just to the left of the brake booster then make sure the wiring at the starter is in good shape. I've had wiring problems in both these locations. If you analize the +12VDC routing of these trucks I noticed a few unnessesary "loops" particularly down by the starter which can be eliminated or at least rerouted higher up which makes troubleshooting easier. I only have 1 heavy gauge cable going to my starter now 
Rewiring with at least 8 guage and mounting a +12VDC battery post up on the passernger side firewall or fender(basically to act as a convienient place to route and tap into +12VDC) is alway a good idea especially with this alt. upgrade. I'd hate to see you give up on this cause it really works well. If you put the original back in and it works then I'm at a loss 
James
Rewiring with at least 8 guage and mounting a +12VDC battery post up on the passernger side firewall or fender(basically to act as a convienient place to route and tap into +12VDC) is alway a good idea especially with this alt. upgrade. I'd hate to see you give up on this cause it really works well. If you put the original back in and it works then I'm at a loss James
79Jimmy said:Well lets assume the alt. is good and check the wiring. The main bat. cable bolted to the back should show +12VDC, again referencing your diagram the #2 wire of the 2-wire plug-in should also show +12VDC all the time, the #1 wire should only show +12VDC when the ignition is in the run position. If these conditions are not met the alt. won't charge. I would first look at the fusable links up on the firewall just to the left of the brake booster then make sure the wiring at the starter is in good shape. I've had wiring problems in both these locations. If you analize the +12VDC routing of these trucks I noticed a few unnessesary "loops" particularly down by the starter which can be eliminated or at least rerouted higher up which makes troubleshooting easier. I only have 1 heavy gauge cable going to my starter now
James
Thanks will try that..
I was thinking about the fuseable link too.. I know I have one but dont know what it is for.. that is why I figured I would hookup the original back up and see if it is charging first... if that is good.. then gotta figure out what is up with going to the upgrade....
one thing I am now realizing that mrk5 said in his post.... 35ohm resistance..
I measured the ohms on the ac delco plug and it is like 500ohms... am I overlooking something?
also James.. so you have done this?
what did you do?
what did you use?
Thanks
Greatly appreciated..
Jeff
mouse
1/2 ton status
Im pretty sure that 35 ohms is the minimum resistance, so 500 is OK...
79Jimmy
1/2 ton status
Jeff,
I just went back and reread your origal post and realized you didn't state which 140 amp alternator you have
All my info and personal expirience is in reference to a CS 144 large case GM alternator. I just assumed that was the swap you were trying to make. Yes I have done this swap into my '79 using a CS 144 from I believe a cadillac application, but I made my own adaper harness without any resisters or bulbs or whatever. It consisted of a CS style haness (just like what is pictured above) but you only need 2 wires from it.
1) The heavier guage "S" wire and
2) The lighter guage "L" wire. Lets forget about colours for now
I spliced it to half a "alternator extention" harness that I picked up at the local auto parts store. It is simply a 1 foot long extention of the old harness with the appropriate male and female ends for my '79. I cut that in half and spliced the female end to the new CS harness. That way I can swap in an old SI alternator at any time. Great trail spare! No cutting of the original wiring.
Again I didn't use/need any resisters and I have a stock volt guage. I wish I had a digi camera so I could maybe make it as clear as mud
James
I just went back and reread your origal post and realized you didn't state which 140 amp alternator you have
All my info and personal expirience is in reference to a CS 144 large case GM alternator. I just assumed that was the swap you were trying to make. Yes I have done this swap into my '79 using a CS 144 from I believe a cadillac application, but I made my own adaper harness without any resisters or bulbs or whatever. It consisted of a CS style haness (just like what is pictured above) but you only need 2 wires from it.1) The heavier guage "S" wire and
2) The lighter guage "L" wire. Lets forget about colours for now
I spliced it to half a "alternator extention" harness that I picked up at the local auto parts store. It is simply a 1 foot long extention of the old harness with the appropriate male and female ends for my '79. I cut that in half and spliced the female end to the new CS harness. That way I can swap in an old SI alternator at any time. Great trail spare! No cutting of the original wiring.
Again I didn't use/need any resisters and I have a stock volt guage. I wish I had a digi camera so I could maybe make it as clear as mud
James
WAHOOOOOO ALL HOOKED UP!!!!!!
18.1 volts at idle and 15.5 volts with 4 kc's, headlights and hi beams on.... YAHOOOOOOOOOOO
now this is the weird part.... my truck has started this thing lately where the battery was getting discharged from sitting... I could jump start the truck and take it for a spin and it would charge up....
now I replaced the alt... and no recharging... thus figuring something I did...
My father told me that this is how you check an alt....
1. stud on back of alt should have voltage with truck off and no key in...
2. also red wire on plug should have voltage too....
3. Brown wire should not have any voltage until key is turned on (Exiter wire)
well 1 & 2 were true but 3 was not....
my father told me to run the battery to the brown wire.. thus I did and now we have voltage.... so some how and some where the brown wire is not good anymore.... thus I ran a new wire from that point into the cab and into accessory.....
I have always had a problem with the electrical in this truck... we had to redo the ignition wire in the fuse box as it wasnt working years ago..... think I need a new fuse box..... but dont wanna bother.....
anyhow... LOVE IT!!!!!!!!!!!!!!!
p.s. thanks for all the good input and assistance....
Steps that worked and without all the crappola post jibberish from me....
1. take original alt out
2. take 1/4" off of back of alt bracket
3. mount new alt in
4. plug acdelco 8078 wire conversion in
that is it...... with the exception of 5. which people shouldnt have to do
5. run accessory wire to brown wire
parts bought...
1. 140 amp alt from 1994 chevy lumina minivan from car-parts.com $34 to my door
2. ac delco wire conversion kit 8078 $23
for $57 I have a GREAT setup!!!!!
the last question I have is what wire is it that I should upgrade? the one off of the stud on the back of the alt to a #8 wire???
18.1 volts at idle and 15.5 volts with 4 kc's, headlights and hi beams on.... YAHOOOOOOOOOOO
now this is the weird part.... my truck has started this thing lately where the battery was getting discharged from sitting... I could jump start the truck and take it for a spin and it would charge up....
now I replaced the alt... and no recharging... thus figuring something I did...
My father told me that this is how you check an alt....
1. stud on back of alt should have voltage with truck off and no key in...
2. also red wire on plug should have voltage too....
3. Brown wire should not have any voltage until key is turned on (Exiter wire)
well 1 & 2 were true but 3 was not....
my father told me to run the battery to the brown wire.. thus I did and now we have voltage.... so some how and some where the brown wire is not good anymore.... thus I ran a new wire from that point into the cab and into accessory.....
I have always had a problem with the electrical in this truck... we had to redo the ignition wire in the fuse box as it wasnt working years ago..... think I need a new fuse box..... but dont wanna bother.....
anyhow... LOVE IT!!!!!!!!!!!!!!!
p.s. thanks for all the good input and assistance....
Steps that worked and without all the crappola post jibberish from me....
1. take original alt out
2. take 1/4" off of back of alt bracket
3. mount new alt in
4. plug acdelco 8078 wire conversion in
that is it...... with the exception of 5. which people shouldnt have to do
5. run accessory wire to brown wire
parts bought...
1. 140 amp alt from 1994 chevy lumina minivan from car-parts.com $34 to my door
2. ac delco wire conversion kit 8078 $23
for $57 I have a GREAT setup!!!!!
the last question I have is what wire is it that I should upgrade? the one off of the stud on the back of the alt to a #8 wire???
Fierospeeder
Banned
im not sure on your alternator. But your alternator should only be putting out a max of 15.2 volts. i might be a few tenths off. 14.7 is average. Your internal regulator might be shot?
And when your taking voltage numbers... is this off the battery?
And when your taking voltage numbers... is this off the battery?
Fierospeeder said:
hmmm hope it isnt bad... but yes this is off of the battery while the truck is running...
the beatings have returned...
ok so now I put my dual 1000ca batteries in.... gonna mount my winch up soon.. just have to get c-channel..... anyway just wanted to do a bump on this as I am going to try and re-start this upgrade again...
will take things slower this time..
truck runs and charges now with a new factory 63 amp alt..
I am putting a 1994 pontiac transsport alt in.... the alt has the 1 wire peg and 3 wire plug...
I have both the 2 to 3 wire delco adapter and a 3 wire pigtale.... so I have all parts to try either way.... will be working on this tonight..... at least mount the alternator and look at stuff...
mrk5 YOU OUT THERE!!!! IT IS BACK!!!!!
I am a glutin for punnishment 
ok so now I put my dual 1000ca batteries in.... gonna mount my winch up soon.. just have to get c-channel..... anyway just wanted to do a bump on this as I am going to try and re-start this upgrade again...
will take things slower this time..
truck runs and charges now with a new factory 63 amp alt..
I am putting a 1994 pontiac transsport alt in.... the alt has the 1 wire peg and 3 wire plug...
I have both the 2 to 3 wire delco adapter and a 3 wire pigtale.... so I have all parts to try either way.... will be working on this tonight..... at least mount the alternator and look at stuff...
mrk5 YOU OUT THERE!!!! IT IS BACK!!!!!
I am a glutin for punnishment 
from your alt to your starter the main line to it, you should be at around 4 gauge to take the full effect of the alt, also the ehavy gauge from your starter to your firewall realy doesnt hurt any either
