Troubleshooting the Charging System on my 1972 Chevy C10 (ol' Yeller)

[@danieljurgill1681]

The BROWN field wire provides a voltage to the rotor field windings so they become magnetic. Once the alternator is in motion the alternator stator sends each of 3 stator windings to 2 different places. One place goes thru the bridge rectifier diode and out to the power out terminal , and the other goes thru one diode of the diode trio component which combine and go back to the regulator . This gives the brown field wire the same voltage on the alternator side , as is on the ignition switch side. With equal voltage on each side , the RED warning alternator light goes out. When the alternator is no longer charging, the power from the battery goes thru the red warning light unrestricted thru the regulator to ground, and hence the red warning light glows . The brown rotor field trigger wire with key on, has a built in resistor in the line, sized depending on the amps designed to go thru the field. On my 85 Chevy, it has a 108 amp factory alternator, and it uses a 10 ohm resistor in the brown wire. When testing , key on, at the regulator brown wire backprobing the connector, the proper voltage is supposed to be only 2 to 4 volts. It does not take much to get the alternator field turning into a magnet.

[@ronvandorin2937]

I have a 71 C/20 and brother , I have the same problem. I fix one thing, and as soon as I get done I have a new problem. Never fails!!!!! I'm having the same charging problem you had. Hopefully your video solves my problem. I think by the time I finish fixing everything I'll have a new truck. Or just start fixing everything again. I'll let you know if it helped, and what my next project will be..........

[@tattedvet8355]

I hear ya.... I have a 81 C10 and every time or every week it's something.... but it's a keeper.

[@israeldiaz2217]

What it was I changed alternator , new battery but I have to turn it on everyday if I don’t used it

[@israeldiaz2217]

So I can keep it from draining the battery

[@edwardnavarro3692]

I am part of that universe also when I fix something, something else breaks.

[@patroll330]

That's a resistor in the brown wire. Not a diode is inside the alternator

[@trailerparkcryptoking5213]

Your doin really good! Every got damn time I fix something, three more things go wrong! 😂😂😂

[@DadbrosGarage]

HAHA, welcome to the C10 club.... where all your money will go, you will spend the rest of your life fixing it and there always be something to buy for it

[@anthonytrent3026]

Got a 72 c-10 as well mine is a 250 /6 cyl same problem replaced the alternator and regulator still not charging I'm going out there tomorrow and check the exciter wire Didn't even think of that thanks man

[@nif407]

Things I noticed: You have a purple wire running out, so, question, is that to the MSD racing ignition? The diode on #4, brown wire to the regulator is supposed to keep the truck from having run on when the ignition is turned off, which, I just added and lost my charge, and, like you, lost continuity, both directions of the diode by ohm theory. Knowing that wire is the exciter wire makes me think that the theory, which worked to stop run on, might stop the charge. I've been back and forth over this theory all day, since, I had a charging system until I fixed the run on problem. The idea from MSD to put a diode on a switched wire to the ignition that creates an open loop just doesn't make sense to me since it seems redundant for an open circuit when the key is off. Also, it's possible that your diode went bad and I put mine in backwards, since, I did reverse my direction, following MSD theory.

[@nif407]

Okay, the diode was bad, the two wires on the alternator were crossed, and the regulator was not grounding to the body. Use the diode setting on the meter to check the diode, and to find the polarity of the alternator wires for the exciter. Run a jump wire off the body of the regulator to a good ground and pull the negative cable on the battery after starting to see if the alternator is working. Presto. A diode costs ten cents. Alternator to regulator is #f and #2. One is positive and the other is negative.

[@the16bitsdigitalboy]

Good video Mr Emerson

[@ronaldsleath6412]

I have a 1971gmc keep up the good work

[@richardflores6296]

Had the same problem I did the as u and fixed my problem thank u

[@michaelphelps5064]

An old alternator/starter repair man told me to never disconnect the battery when the engine is running. It could fry something in the alternator. Cant remember what.

[@Gunnyfelker]

My dad used to start 3 cars with the same battery by moving it from car to car. Those were old 1960s cars though.

[@chevyengine307]

New project get engine started

[@jdiaz9759]

I get 12v to the exiter wire when its not hooked to the alternator, when its hooked up to the alternator I get around 4.5. is that normal

[@aureliogalvez3139]

So all you did was hot wire the "excitement wire" to the red power cable?

[@the16bitsdigitalboy]

By the way nice system

[@chevyengine307]

Yeah water does that

[@PANDA-PANDA59]

Having charging issues with my 71 c10