Lights dim when car shifts gears

My girlfriend’s car has been having an issue where the headlights dim when the car shifts gears. Once the shift is done then the lights return to their normal brightness.



She took her car into the shop to have the alternator checked since that was our first guess but the alternator appears to be fine. They replaced a belt that was worn but the problem still persists. Any ideas what could cause this behavior?



Erik

It’s pretty hard to help when you want us to guess what kind of car it is and whether it’s an automatic or manual transmission.

Sorry, it’s a '97 Nissan 200SX with automatic transmission…