2G Voltage reading at ECU pin 41 (Generator FR Terminal)

[onlyoneromeo]

What should my voltage be at that point. I took a measurement there and it was 4volts if its low does that mean its the alternator?

P.s. its for my 99gst

 

[luv2rallye]

That is an alternator (alt) sensing line (connects to green wire on alt 4 pin connector) and varies with alt current load. ECU uses it to control IAC. Voltage goes lower with more alt current draw. With engine running and alt connected but all other electrical stuff off, it typically is over 8v. If alt is not connected you may see 4v there since it has a 5v pullup inside ECU.

 

[onlyoneromeo]

I know for sure that It is connected. Does that usually signal that there is a bad alternator ? Is there something else I should be looking for ?

 

[luv2rallye]

No that is not a sign of a bad alt. Measure voltage at battery with engine running - should be over 14.0v and drop no more than 0.5v when you turn lights on. For a more complete test: http://www.dsmtuners.com/forums/new...reeway-electrical-problems.html#post151165661