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Fellas I just can't figure out why my alternator won't charge. It tests good, new regulator, new relay, voltages all where they are supposed to be except the circuit back from the relay to the battery. I have battery voltage to the top pin on the relay plug and 5 volts to the left leg of the relay. Is that not enough?
What is this relay you talk about?
Is this the starter solenoid?
So meter negative to battery negative and meter positive to battery positive motor running what do you get?
If you put the posative to the ALT out put stud what do you get
Dave. ----
Pictures might help. There is nothing called a relay in the charging circuit that I know of.
If all wiring is correct, no bad parts, and there is no increase in voltage between the engine off and engine running, there are two things I can think of offhand that may come into play.
One is a bad ground. The screws holding the regulator to the fender well provide ground. If they are loose or stripped, the regulator will not work properly. Run a wire from the battery ground to the base of the regulator and see if that changes anything.
Another thing I see that is often overlooked is underdrive pulleys. If the crank pulley has been replaced with a smaller version, the RPM has to come up much higher before you will see any charge at the battery.
Fellas I just can't figure out why my alternator won't charge. It tests good, new regulator, new relay, voltages all where they are supposed to be except the circuit back from the relay to the battery. I have battery voltage to the top pin on the relay plug and 5 volts to the left leg of the relay. Is that not enough?
Does the truck have gauges or does it have warning lights in the dash for oil pressure and battery?
Stock pulleys, D/C gauge which I don't think works, truck dies if the battery cable is disconnected. I have a battery ground wire to the voltage regulator and relay. Battery voltage off the alternator stud. Relay is just left and below the voltage regulator.
That relay has nothing to do with charging as I believe it is the horn relay.
That voltage regulator dose not look to have a good ground to the fender and can not be bolt there or the hood can not close.
It also is not good to disconnect the battery when running as it can hurt the ALT & regulator and any electronics.
Find where the regulator should be mounted make sure it has clean metal for the ground when mounted.
Pull the plug off and look over the connector if it is clean..
Then see what you have..
Dave. ----
Yes the hood closes with the regulator there. Yes it has a good ground and I ran a wire from the bolt to the battery. The left wire off that relay runs to the charge side of the solenoid. Earlier I said there was voltage to it but it's actually the right wire that has 5 volts.
I'll get some pictures up of the new wiring later today for you if the 3G Upgrade interests you.
I started this project off with a 10SI GM alternator conversion which I can get to work except it drains my battery and I haven't figured out how to get the alternator to work with key start power. It'll run with constant 12V on the exciter wire but not if I take it away.
What voltages are supposed to be on each pin of the voltage regulator?
The green with red stripe that feeds the voltage regulator should have full battery voltage present with the truck running. The orange is the field wire which will vary depending on the yellow wire which senses voltage. Confirm you have voltage to the green/red wire.
The free with red stripe that feeds the voltage regulator should have full battery voltage present with the truck running. The orange is the field wire which will vary depending on the yellow wire which senses voltage. Confirm you have voltage to the green/red wire.
I thought the whole appeal to the GM 1 wire alternators were they are '1 wire.' Simply one wire going from the alternator to the starter solenoid battery side or battery hot. If that's the case, the voltage regulator should be deleted altogether...the 1 wire alternator is a self exciting charging system.
Eric, that's correct. There are true 1 wire alternators, the 10SI is actually a 3 wire + ground. Of course I fell down the rabbit hole of YouTube videos and it sure looked easy enough.
The 10SI exciter wire is supposed to work when wired to start 12V power + a idiot light. The light uses excess energy from the start cycle.
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