truck alternator - here is how its wired.

big power cable straight to battery in the back.

B cable on connector( second one from the left when sitting in drivers seat) connected thru a 470 ohm resistor to 12v

C cable (third one from the left when sitting in drivers seat) connected to 12v


why could it not be working?

 

ok, I have a newbie question.

I checked the resistance of the 470ohm resistor and it is 470 ohms(1/2 watt)

yet, when I apply 12.5 volts to one side, I get 12.5 volts out the other side, not 5 volts. I hope I didnt destroy the alternator. what am I doing wrong?

 

Not sure why it seems alt's are such an issue w/ these swaps. I ended up using a warning bulb, 194, coming from 12v switched, then have that going to pins B and C. This is working for me, may not be exactly right, but it hasn't failed me.

If you don't have a 194 bulb holder (if you've gotten any aftermarket gauges, they use 194 bulbs/holders) try that out.

 

thanks for the information. I happen to have a couple of those laying around.

do you have to run a ground?

 

No, just the power, after the bulb, going to B and C.

 

thanks.

ok, to clarify, my bulb has positive and negative. I hook a lead from 12v to positive, and a lead out of negative to the alternator?

 

What is the problem? you only have 12.5 on your voltmeter? or 12.5 when accessories are used? Or 12.5 at the alt power lead is being produced or 12.5 at the battery not charging?


Bozz

 

hey Bozz, I was only getting 12.5 while running to everything.

but, I replaced the resistor with a lamp tonight, and of course it works. sometimes it makes no sense because the resistor was dropping the voltage down to 1.26 and the lamp was dropping it to 1.28 so they are very close. I just dont have any explanation for why the resistor didnt work but the lamp does

thanks RvP and Bozz

 

What year bro alt?..... I had a low voltage issue with my setup.... it would be 12.5-12.7 when car was running:

if I turned the healights on 11.8-12
turn the radio up 12-12.5
press the brake, voltage drop as well...

So I went back and tracked back how its all setup/69 Chevelle... well the 06 GTO alternator I have has:
B+ lead: wire going to the battery(voltage sensoring done here)
L lead: lead to the 3k ohm resistor (50mA max )
Ground connection (via the installation bolts)

The voltage sensing is done at the battery especially since I do not have a external regulator as such... Also with the old chevy 68-72 muscle car wiring aka Chevelle..... The external regulator regulated the voltage by sensoring the voltage at the junction/horn relay.... Now this will affect the rest of the car...

With the one wire alternator setups, them problem is the voltage sensing.... and depending on your alternator, your going to have to find a way for the alternator to be able to sense the voltage at a junction with your accessories.. With most 1 wire Alt, if the voltage sensoring issues is not handled, all your alternator is doing is serving as a great battery charger.

My motor and engine harness runs self sufficient of the Chevelle factory harness I have primarily.... I used the GTO engine relay/fuse box and the inside fuse box from the gto......

Now with our LSX conversions most do not have anything from the engine harnesses getting a voltage sensor signal for the accessories of the car/ Chevelle....

Now in our Chevelles all of the acessories are primarily receiving voltage at the horn relay/junction, most located on the driverside by the radiator and headlights..

My problem was the horn relay screws were rusted and corroded, plus I think the relay was bad... I went to Oreilly, bought a new horn relay.... problem solved..... now I have 13.8-14.0 on the digital, healights on 13.5 I also made sure I had a good 8 gauge wire from the horn relay/junction to the battery.

Remember our cars 68-72 muscle cars, the main voltage sensoring is done at the junction/ horn relay and serves as a junction.... From this junction aka horn relay is a wire that runs from there to the battery..... Now if you have deviated from this setup as such or put the battery in the trunk, then this may be a problem.... depending on your wiring.. The reason why I bring this up is becuase however you have it set up, how does your truck alt know when to activate the internal regulator from voltage sensoring?




Bozz

 

thanks for the info man