Andyboy980

i have ls430 and I noticed each time I turn the lights on the idle gets hire, checked my alternator and it’s in good shape. Can somebody please help me.

ltd76gold

A hundred to 150 more turns at idle with all of the lights on.... Possible. What does your tach read before lights... After lights?

Andyboy980

It reads about 650 before light after light about 850

ltd76gold

I don't think you have anything to be concerned about. The system is just increasing idle speed so the current draw is met.

​​​​​​​Battery in good shape? Tested? Even if it is good, I still think your OK with that little rpm change.

bradland

Modern headlamps consume a lot of power. Alternators produce more amps the faster they spin. The ECU in your car adjusts the idle accordingly.