Alternator will not charge until I slave it with running truck

[Coffey1]

I have 24 and 12 volts at alternator 24 at excite terminal
No charge the second I plug slave cable to another truck running the alternator starts charging with flashing green lights

 

[Coffey1]

Brand new batteries

 

[Jericho]

have you lost the field on the alt, look up "testing field" and see if you have a charged field

 

[simp5782]

What about with the headlights on?


I have one that will drop voltage and and not charge until I throw a load on it

 

[Coffey1]

Tried every thing.
With truck running the lights on regulator will flash back and forth amber.
Start other truck up put slave cable on and truck starts charging and lights on regulator start flashing green.
Shut truck off that's slaving truck and no charge and lights flash amber.

 

[Ronmar]

Dosnt sound like your alternator is putting out anything at any point. If the other truck is running, you are not really charging/delivering any current out of the alternator, as the other truck is doing that. This is pushing the voltage on the busses up to the point where the regulator thinks it is doing its job and it goes green...

found this a while back, might help you wring out the windings to determine what is wrong...

https://www.ceniehoff.com/Documents/Ctrl_Hyperlink/TG0018A_uid12172009221392.pdf

 

[scottmandu]

Check each individual battery voltage first.

 

[Coffey1]

Changed alternator alls good in the world again