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On the connector it should have 4 letters it's the P one that exites it. I have it connected to my switch on ignition. But with a small light in between. Works good 14.5 volts all day
Your supposed to run a resistor inline it needs 5 volts. Any more and it burns up the alternator. There are quite a few write-ups on it here. I just put a 1993-1994 4.3 S10 alternator on the truck bracket and forget about it.
So the brown wire "I" connects to the starter wire (purple for GM IIRC)? So the excitor wire only gets power when the car is cranking?
Also the "S" can be added as the load for the alternator into any 12v service. Not directly to the battery + as that defeats the purpose. In my alt loom this is a light gray wire.
Voltage will fluctuate a little bit so I am hoping the system voltage is being read from the Gray wire and adjusting as needed.
It is tough to see but there is a 47 Ohm (50 on paper) resistor underneath the heat shrink on the Brown wire.
PM me if you need the resistors, I have 49 left over! Because Amazon.
Before the Alternator did not charge at all, the truck ran on only battery power with the "one wire" +pole setup. The battery was slowly draining out as the truck ran.
Right now I have the trickle charger on the battery so that we are full up + when needed to crank. Also note that the MSD is VERY sensitive to power fluctuations! Needs good ground and a solid 12v to run right, even if the starter turns don't assume it is enough for the the MSD. Put power to the MSD on a relay if you can.
Voltage will fluctuate a little bit so I am hoping the system voltage is being read from the Gray wire and adjusting as needed.
It is tough to see but there is a 47 Ohm (50 on paper) resistor underneath the heat shrink on the Brown wire.
PM me if you need the resistors, I have 49 left over! Because Amazon.
Before the Alternator did not charge at all, the truck ran on only battery power with the "one wire" +pole setup. The battery was slowly draining out as the truck ran.
Right now I have the trickle charger on the battery so that we are full up + when needed to crank. Also note that the MSD is VERY sensitive to power fluctuations! Needs good ground and a solid 12v to run right, even if the starter turns don't assume it is enough for the the MSD. Put power to the MSD on a relay if you can.
Thank You!!!
Putting the L and S terminals together like you have is worthless. The idea behind the S terminal is that you wire it to a place where all of the accessories draw their power from. This way the alternator can sense the load and adjust output accordingly.
Putting the L and S terminals together like you have is worthless. The idea behind the S terminal is that you wire it to a place where all of the accessories draw their power from. This way the alternator can sense the load and adjust output accordingly.
Andrew
I agree with you 100% the S wire should go to the point where most of the accessories draw their power, like the fuse box. The voltage regulator inside the alternator will adjust the output to keep the voltage there constant. Like someone else said do not connect the voltage sense wire (S) to the battery.
I struggled a bit on where to tap the L wire. It needs to be switched with the key, but no reason they both can't be connected to switched wire in the fuse box.
Agreed! And it is is. The picture just makes it hard to show.
The yellow wire is from the switched ignition off the factory fuse box. Not bad for original 1971 coloring! Reused the +12v from the old electric choke.
Putting the L and S terminals together like you have is worthless. The idea behind the S terminal is that you wire it to a place where all of the accessories draw their power from. This way the alternator can sense the load and adjust output accordingly.
Andrew
So if main ignition/accessory power feed is pulled from the battery?
How does the alternator behave without the S terminal connected, while running 5 volts to the L terminal only??
So if main ignition/accessory power feed is pulled from the battery?
How does the alternator behave without the S terminal connected, while running 5 volts to the L terminal only??
I have my S terminal wired essentially to the battery, because that is where most everything gets its power. Other people have a main power distribution bar and they wire the S terminal there.
As I recall, without the S terminal wired, the alternator will putt out a steady 13.7 volts. However, once more load is added, the output will drop. This is exactly what happens in my GTO swap, as it does not have the S terminal wired. When the coolant fans kick on, there is about a .5v drop. When the turn signals are on, you can see the needle on the volt meter bouncing to the rhythm of the blinkers.
On my Cougar swap, I have the S terminal wired to the battery (essentially) and it does not behave the same way. Voltage is steady when the fan kicks on, but then again my fan is PWM controlled so I do not have a large amp spike.
Wiring the S terminal is easy and there is no reason not to do it. No downside.
I have my S terminal wired essentially to the battery, because that is where most everything gets its power. Other people have a main power distribution bar and they wire the S terminal there.
As I recall, without the S terminal wired, the alternator will putt out a steady 13.7 volts. However, once more load is added, the output will drop. This is exactly what happens in my GTO swap, as it does not have the S terminal wired. When the coolant fans kick on, there is about a .5v drop. When the turn signals are on, you can see the needle on the volt meter bouncing to the rhythm of the blinkers.
On my Cougar swap, I have the S terminal wired to the battery (essentially) and it does not behave the same way. Voltage is steady when the fan kicks on, but then again my fan is PWM controlled so I do not have a large amp spike.
Wiring the S terminal is easy and there is no reason not to do it. No downside.
Andrew
So with the way I have wired my car I should be able to run a wire from the S terminal onto the alternator main output/battery terminal (which runs parallel with the battery lead to the battery) to achieve the same thing?
the S wire should go to the point where most of the accessories draw their power, like the fuse box. The voltage regulator inside the alternator will adjust the output to keep the voltage there constant. Like someone else said do not connect the voltage sense wire (S) to the battery.
10-23-2013, 10:38 PM
