Alternator Light Stays Lit.

[AMC86MJ]

OK from the files of should have known better but did it anyway. I jump started my riding lawn mower with my Comanche and now the alternator idiot light stays on. It's been like this 6 weeks now and with winter approaching i'm gonna fix it. My question in jumping my mower what did I damage that caused the idiot light to illuminate and how do I repair it?

[yxmj]

First.....The light more or less works like this.....Turn your key forward for power (not to start) and it gives 12v to one side of the bulb and the other is effectively "Grounded" to the alternator....The bulb lights up.

 

When you start the engine and the alternator is producing power that brings the "grounded" side up to 12 volts, so effectively eliminating the voltage drop and the light goes out.

 

The fact that your light is glowing shows that your alternator is not putting out enough voltage.

 

Here is a good video to show how to test it without taking it out

 

 

. :MJ 1: .

[carnuck]

Try bumping the alt with a rubber mallet and see if the light goes out.