Electrical problem

On my 2000 Chevy Tracker, the lights “pulse” when driving.

Are they in danger of going out?

Yes, they will go out–as will all of your other electrical equipment–when the alternator totally dies.
Right now, it is giving you clear signals of its imminent demise, and I hope that you heed those signals before you wind up being stranded on a cold night.

Get the vehicle to your mechanic a.s.a.p.

First, give the battery terminals and the engine ground cable all a good cleaning…Did that cure it? No? replace the alternator. Most parts stores can bench test them free…

The pulsing is usually due to bad diodes in the alternator. It causes a high ripple voltage on the charging system. Like the others stated, replacing the alternator should fix the trouble.