Surging Dash and Headlights???

[WagoNan]

Hello Everyone!

I am completely baffled by the behavior my automatic 2003 9-5 Wagon is currently exhibiting. Often when I start the car, am idling at a red light, etc., the headlights and all of the lights on the dash dim down and then brighten back up again in a slow, rhythmic pulsing. It only happens when the car is idling or when I am moving very slowly. Once I pick up speed it goes away, but will come back if I get stopped at an intersection. It doesn't always do it, but it is happening more and more frequently. What do you think could be causing the issue? Alternator?

Thanks!

[DebtFromAbove]

Replacing the battery is probably cheaper, and certainly easier, than replacing the alternator. I would start there. Replace your battery, or try a known "good" one for a few days. If the problem persists, then move on to the alternator, etc...

[Mike Brennan]

My guess is the voltage regulator brushes are getting short. It can be replaced in your alternator. I have done it without having to remove the alternator out of the car. I just replaced it after removing it from the motor. Hard to get it completely out. Any competent garage can do it.
First test the battery, but it does seem like the VR.

[psymon]

I had this exact issue. Replaced the alternator and things have been fine for years.