help...alt,charging problems

[Evan's f250]

ok a have a 78 f250 that wasnt charging at all. so i take off alt and have it checked and it came bk as fail twice,so i bought new $30 valucraft alt. i get it home it has 4 studs instead of 2 that old alt had,the 2 wires on the old alt was hooked to the one and only stud other than main powerthey were orangishred color and other was whte/black,these two wires were hooked together on old set up. so on new alt it has stud for main pwr wire,one labeled F,anothr one S,and one labeled grnd. so i hooked up the way it said in instructions(orange to f, white/black to S, and even hooked ground wire to the battery to the grnd location. it wouldnt charge yet after installing,so i head bk to auto zone and wanted to gt new alt tested and machine was temporarily down,so i go up the road to advance and they test it and said fail but the person acted clueless on how to do the machine,so go bk autozone and machines back workin and they run it and it passes the test twice,so i buy a regulator, now it still nt charging what could be the prob??? my truck has idiot lights and ik some vehicles if the light bulb is burnt out,the alt doesnt charge and ik most the lights on that side are burnt out..do these trucks do that? i just bought truck month ago and nt even drove it so idk if it was ever set up right


thanks in advance,
Evan

 

[Mil1ion]

The bulb has nothing to do with whether it charges or not.
It is merely a warning light that the alt or VR is failing.

Do you have a muliti-meter ?
Set it for 20 volts

Hook it up and take the engine off idle to about 2000 rpm if the needle rises.

If you have someone to help you turn lights,wipers,heater motor while you watch the multimeter it is a lot easier to test

 

[Evan's f250]

yes ive already done that also. now today i check the 2 wires,the orange one which is suposed to go to F on the alt and the white/black one that goes to S on alt. (the wires are marked F,S, etc coming from voltage regulator) and either of them had power with key on. i used test light. so now im thnking run a wire tht turns on with key on (run postion) with high ohm resistor to either the S or F..but idk which one bc im unsure of what either does. which one is suposed to be the alternator exciter wire, S or F?

thanks,
Evan

 

[Mil1ion]

 

[Mil1ion]

 

[Evan's f250]

ok thanks.. my trucks wiring is a lil messed up, it has a push button start. anyways by the diagram it looks as if the one labeled "I" on volt reg goes to the red/blue wire on ignition,ya thats the one that has been altered. so the way i took it is the wire on "I" on volt regulator is supposed to have pwr when key is on and then engage the S and F wires off of the voltage reg to the alt and makes the alternator wrk? correct me if im wrong wiring aint my thing. and if i nd to run a wire to the "I" from the ignition switch is a resistor required,i assume yes.

Thanks,
Evan

 

[Mil1ion]

The I connection wire is for 12volts of power while the starter is cranking to ease the engine starting
Once the key is returned to RUN, only 7-9 volts runs the ignition thru the 42" resistance wire under the dash in the wiring harness

The Big Lug on the starter relay is merely a power junction spot where power is always trhere when the battery is hooked up, and how the power the Alt/VR creates goes to the battery to recharge it.

 

[Evan's f250]

ok i see a prob now. ok 1st off my truck has a push button start..turn key to run and push it and it starts.the push bttoon is hooked up to a red wire on ign switch that gets pwr with it in the run position. anyways on the solenoid it only has a wire coming from the push button connected to terminal S on the solenoid. the red wire for S and brown wire for I are both just sitting there unhooked off the solenoid. and also the plug that goes into the voltage regulator has no wire coming out of plug on the one labeled I. with that said what is needed to get my alt charging.
thanks,
Evan

 

[Mil1ion]

Hook up the brown wire to the I on the solenoid.

Can you take a pic and post it ?

 

[Evan's f250]

Hook up the brown wire to the I on the solenoid.

Can you take a pic and post it ?

thanks Mil1ion i hooked up brown wire to I on the solenoid as above and charges great. thanks alot..thats finally over with.

Evan