ECU monitors alternator load

[mickyTDI]

Going through the measuring blocks on vagcom today i noticed a block that measures alternator load. Anyone know why the ECU needs to monitor this?

 

[Sooch]

Just guessing here from my gasser tuning days. In order to keep a steady idle, at all engine loads, the ECU needs to monitor the alternator to sense when seat heaters, rear defroster, AC or even just the cooling fan come on. The ECU will add more fuel to compensate for the higher load and keep idle at 903 or whatever it's set at.

 

[Drivbiwire]

...Smooth Idle Control... (I think thats the term they use)

Newer cars will actual shed loads in certain situations to protect the elctrical system or to save the battery to insure a start (yes with the car off even then the ECU is still watching).

DB

 

[mickyTDI]

Just guessing here from my gasser tuning days. In order to keep a steady idle, at all engine loads, the ECU needs to monitor the alternator to sense when seat heaters, rear defroster, AC or even just the cooling fan come on. The ECU will add more fuel to compensate for the higher load and keep idle at 903 or whatever it's set at.

That's what i initially thought but isn't there an engine speed sensor that monitors the rpm.