alternator?

[re-ride]

so I have the surging headlights. Well everything electrical is surging, pulsing whatever you call it. 02 Nissan frontier. So I'm thinking replace alternator. The only thing that seems odd to me is the pulsing stays constant regardless of engine speed, whether I'm idling or highway speed. When at idle the engine sound pulses in time with the lights. For some reason I thought the faster engine speed would increase the electrical pulsing, but I guess not

[Snafu]

I have heard of this problem but I do not recall the solution. When you measure the voltage can you detect the pulsing? If you can then try measuring off the alternator and work your way towards the battery. If it pulses off the alternator then it needs rebuild/replacement.

[Morpheus]

Probably a bad diode in the alternator.

A charging system diagnostic would confirm this.

[Nd4SpdSe]

Indeed as Mike said, probably a bad diode, so you're pumping out half-AC