3G alternator swap problem
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3G alternator swap problem
Hi
I just made a 3G alternator implant in my 84 F250 6.9. With old alternator when I put the lights on and heater fan to full I get the reading only 12V. Today I put the 200A 3G alternator in and I get the same reading in the volt meter. When I change to bigger alternator on my 84 dodge van I had to bypass the amp gauge to work properly is here the same problem or I have some other problem?
Thank you
I just made a 3G alternator implant in my 84 F250 6.9. With old alternator when I put the lights on and heater fan to full I get the reading only 12V. Today I put the 200A 3G alternator in and I get the same reading in the volt meter. When I change to bigger alternator on my 84 dodge van I had to bypass the amp gauge to work properly is here the same problem or I have some other problem?
Thank you
Senior User
Joined: Oct 2012
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Did you make sure you accurately replicated the connection/schematic changes between the old and new system? You pretty much throw out all of the old wiring and regulator in the process, but what replaces it is pretty simple.
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
Welcome to the forum Filko! 
Your diesel should have had a 1G alternator with external regulator.
Did you get a 1-wire alternator to replace it?
Have you checked for voltage coming from the green/red wire with the ignition on?
Does the battery light come on in the cluster when you turn the key to run? (before starting)
Your diesel should have had a 1G alternator with external regulator.
Did you get a 1-wire alternator to replace it?
Have you checked for voltage coming from the green/red wire with the ignition on?
Does the battery light come on in the cluster when you turn the key to run? (before starting)
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I have a 3g alternator, white whire on the stator, yellow on alternator +, and green red on original green red wire. Big yellow, red and yellow green on + on alternator.
I don't have a baterry light on before staring or maybe is not working??
voltage on green wire is 11.57 when heating plugs are off which is low by my opnion. what could be wrong??
I don't have a baterry light on before staring or maybe is not working??
voltage on green wire is 11.57 when heating plugs are off which is low by my opnion. what could be wrong??
pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
If you don't have power -through that filament- you will not charge.
Most diagrams show a 510ohm resistor in parallel to the bulb so the truck will charge if the light burns out.
Try checking the fuse or changing the bulb, that should get you going.
(EDIT)
I did not read that last sentence when I replied...
Maybe you don't have the 'optional' charge lamp?
If you only have 11.57v showing, maybe the batteries are just low?
How much voltage do you have across the +&- terminals?
That should be more than enough to excite the alternator into charging.
Most diagrams show a 510ohm resistor in parallel to the bulb so the truck will charge if the light burns out.
Try checking the fuse or changing the bulb, that should get you going.
(EDIT)
I did not read that last sentence when I replied...
Maybe you don't have the 'optional' charge lamp?
If you only have 11.57v showing, maybe the batteries are just low?
How much voltage do you have across the +&- terminals?
That should be more than enough to excite the alternator into charging.
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 39
From: EXTREME southwest CT
Oh, move anything but the charge cable and the yellow/white regulator wire off the alternator and on to the battery+ post of the solenoid.
You don't need all that garbage hooked directly.
You don't need all that garbage hooked directly.
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pedant
Joined: Jan 2008
Posts: 23,576
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From: EXTREME southwest CT
With a 200A alternator you really should be using a 0 gauge charging cable or larger (lower numerically) and a 225A Megafuse before the solenoid stud.
https://www.vtewarehouse.com/content...a/megafuse.php
Thankfully Ryan's oldfuelinjection.com website is still up and running.
https://www.vtewarehouse.com/content...a/megafuse.php
Thankfully Ryan's oldfuelinjection.com website is still up and running.
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pedant
Joined: Jan 2008
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From: EXTREME southwest CT
Go save the whole "alternator files" list.
There are many more that I use that aren't even indexed.
Like the various comparisons of mounting styles and body sizes, 2-hole vs 4-hole, etc..
The 3G install tech page would be a good one too.
It shows where to grind the cast bracket on serpentine Weezers.
Credit and thanks to Ryan for making this resource available to all of us!
Sorry for the hijack Filko.
There are many more that I use that aren't even indexed.
Like the various comparisons of mounting styles and body sizes, 2-hole vs 4-hole, etc..
The 3G install tech page would be a good one too.
It shows where to grind the cast bracket on serpentine Weezers.
Credit and thanks to Ryan for making this resource available to all of us!
Sorry for the hijack Filko.
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From: Virginia
I would hook it up like the lower diagram(I think you already have if I read post #5 correctly) and then as a test I would take the green/red from the alternator and touch it to the battery + while the engine is running. If the voltage jumps up to what you want it to be(around 14v) then you know you have a problem with the green/red wire, probably a poor connection up in the cluster.
My diesel did come with a alternator idiot light AND a voltage gauge. If yours originally had the green/red going to the "I" terminal of the old regulator, then you do have a dash idiot light somewhere.
My diesel did come with a alternator idiot light AND a voltage gauge. If yours originally had the green/red going to the "I" terminal of the old regulator, then you do have a dash idiot light somewhere.
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Alternator is working fine when I start up the engine, it has 14 volts, if I turn on the lights there is no drop in the voltage but when I put the fan on high position voltage drops to 12,5V. Alternator is 200A and this voltage drop shouldn't happend.
I have 200A alternator in my 84 dodge and there is no voltage drop and I have lights on, AC on full, radio with amp,...
If I understand right, the main lead for the interior is the yellow wire and this one feeds all what is in the cabin right?
I will check the fuse box in the back side if someething is wrong there is there something else to check?
I have 200A alternator in my 84 dodge and there is no voltage drop and I have lights on, AC on full, radio with amp,...
If I understand right, the main lead for the interior is the yellow wire and this one feeds all what is in the cabin right?
I will check the fuse box in the back side if someething is wrong there is there something else to check?
pedant
Joined: Jan 2008
Posts: 23,576
Likes: 39
From: EXTREME southwest CT
Be mindful that it is an electric circuit.
I would check the cab grounds (I'm assuming the blower is grounded there)
Not sure of your truck, but my cab has a ground strap below the DS floor from the pinch weld to the cab support.
I would check the cab grounds (I'm assuming the blower is grounded there)
Not sure of your truck, but my cab has a ground strap below the DS floor from the pinch weld to the cab support.