Tractor involved, CASE 480E, LL Help, my dashboard alternator light will not turn on when I turn the ignition key to start the tractor. The dashboard light does work, I bypassed alternator and hooked up a separate 12 volt power supply and got the dashboard light to illuminate. All of the wiring has continuity after checking them with my multi meter. I believe the alternator is charging when the engine is running, the battery hasn't drained and the volt meter dashboard instrument does display good voltage. Is there something in the alternator this is defective, if so can I replace the defective part without removing the alternator?
I don't understand that one, most of the time everybody don't wanna see that light turning on. If the light is turned off when engine running and alternator is charging, I will let it like that!
I may be confusing the situation by posting this because this is from a totally different machine. But the circuit may be similar and I never totally understood how that light works. IF they work the same way the +12VDC comes thru the ignition switch and the ground circuit is from the alternator. Maybe with this INCORRECT drawing I found you can determine what is going on with yours. View attachment 580se_Alt_Light.pdf Maybe someone else will know if this is even similar to the 480E...
It should be similar Bowen. The 480E parts book shows it to be a three wire alternator. Also your .pdf link explains the function of the light quite well. The picture of the alternator is the one shown in the online parts book. Miklav ; One way to check and see if the alternator is charging is to tempoarily hook a plain ole amp meter between the battery wire and the alternator. That is the wire that has the nut #25 on it in the picture. Here is a link to a different idiot light problem, but the diagnosis procedure is excellent. http://www.practicalmachinist.com/vb/general-archive/alternator-idiot-light-78415/
Wow havn't messed up a post that bad in a while
There is no practical difference if it is fed from the ACC. terminal of the switch as it is hot in conjunction with the IGN. post, if you look at the schematic of the switch you will see that both are shown as open, when the switch is turned to IGN the contacts will both move to a closed position. Both schematics are functionally correct. The alternator technically does not ground the light in a conventional manner, rather it allows current to flow back through itself to a negative potential, in effect a ground BUT that same terminal becomes hot when the alternator is running and the voltages balance so no current flows through the bulb the bulb will read 12v on either side and be extinguished.