Hey guys hav'nt been on here in a while but I am in need of some help I am working on the alternator on my 38 chevy truck some of you may know it as the grandfather grandson project. The first alternator I had on it was not putting out any volts when measuring it from the one wire hook up (that connects to battery) then to ground. After that I bought a brand new one thinking that one is bad and now I am getting the same thing with the brand new one. When the battery wire is connected the only thing reads is the 12 volts from the battery. I tried connecting a jumper wire from the #1 terminal to the battery hook up on the back but it did not change anything. So back to my main question does anyone have any idea why it is not putting out any volts (12-14) like it is supposed to?
Probably is a external regulated one ,so need a regulator. Take it to a shop that rebuilts auto electrics and they can tell you what you have.
Don't go 1 wire. There are charging issues at low rpm. In other words.... it don't charge at low rpm.
Assuming its a 10SI type alt looking at it from the back with the plug at 12 o'clock the #1 terminal on the plug (nearest to the larger Batt terminal) is switched 12v from ignition the #2 can jump direcftly to the Batt terminal.
russco I tried jumping the the #1 terminal to the battery terminal i know and did not get anything I think I tried the #2 also should I deff. use a jumper wire from #2 to the battery Also JohnEvans it does have an internal regulator this is the link to the alternator i bought http://www.autozone.com/autozone/pa...i?counter=5&itemIdentifier=333906_188920_4676_ Thanks for the help so far guys
If you look at the two spade terminals, the drivers side is the 12 volt switched and as was said, the passenger spade, you can hook that to the larger terminal on the alternator that hooks to the battery. Simple as pie. If you don't get at least 13-14.4 volts while running on the terminal that runs to the battery you have another bad alternator. No plug hooks to the ground as the chassis is ground. Also for those that don't know this, if you put a screw driver on the back side of the alternator at the center, there should be a strong magnetic pull. If there is not, you are not charging and you will have a dead car shortly. Its a simple test. Anything steel touching the back center of the alternator will tell you. I change alot of external voltage regulatedr cars to this type. Internally regulated alternators work way better than the external ones. Probably converted at least 15- 20 60s muscle cars to the one you have.
i went with a 1 wire i rev it up once to 3500 or 4000 and then it keeps charging. once it hits it charges no matter what rpm i go down to. never had a problem with it. I will get the model and post it later.
thanks guys I will take another look at it on sun. and see what I can come up with. One last question I am not familiar with this and this may be a dumb one but where is the #1 terminal supposed to go? (voltmeter or ?)
#1 terminal is 12V switched power (so when the key is turned to the run position you have a constant 12v supply to the number 1 terminal on the alt). The # 2 terminal can jumper right over to the Batt terminal on the alt. and a 8 or 10 guage wire from the Batt terminal to the battery and thats it. In some situations a diode will need to be put in the #1 terminal wire to prevent "backfeeding" thru the ignition.
Diagram attached: I do not have an idiot light but there is a resistor that came in the #1 white wire.
Rev thet sucker up! Even if it's a 3 wire, it'll charge using only the big wire to the battery. I know...used both 1 wire [different regulator] and 3 wire. Either one WILL charge [using only the main wire from alternator to battery] by simply reving the engine to about 2500 RPM after starting the engine. Don't believe it? Try it.
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