Alternator "tridiode?"

[Sir A.Y. Atoyot]

Originally Posted by Yarisduder

My electric system dummy light came on the other day, so I figured it was the battery since I was told it is weak. So replaced the battery, and they tell me that the "tridiode" on the alternator which "sends the signal to the dash light" is faulty. The symptom it causes is that the electric light comes on when the car starts and goes off shortly afterward, but the system still charges fine. They say to fix it I'd need a new alternator, but since it's charging it's a waste of money to do that.

So my questions:
1 - Is this "tridiode" even a real thing?
2 - Can just the "tridiode" be replaced?
3 - Or is the real problem a corroded contact?

Thanks.

It's usually called a "diode trio." It supplies power to the regulator. It can be replaced on most alternators that have them. Sometimes they are integrated with the main rectifier assembly and sometimes they are a separate piece.

[CTScott]

Originally Posted by Sir A.Y. Atoyot

It's usually called a "diode trio." It supplies power to the regulator. It can be replaced on most alternators that have them. Sometimes they are integrated with the main rectifier assembly and sometimes they are a separate piece.

On the Yaris, it's integrated into the voltage regulator assembly.

[Sir A.Y. Atoyot]

Originally Posted by CTScott

On the Yaris, it's integrated into the voltage regulator assembly.

Sorry, not to quibble, but an examination of the schematic doesn't show any diode trio component, inside or outside the regulator. Apparently, there is no diode trio present in this design.

On an alternator that does have this component, one end of each of a trio of diodes is connected to the phase windings of the stator, while the other ends are tied together and attached to the regulator. Compare, for example, the ubiquitous Delco 10si alternator, which has a diode trio as a separate component.