I have a 2002 Monte Carlo SS 58,000mi. The car has been trouble free -EXCEPT - about 4yrs ago, the headlights and dash lights flickered while driving. Eventually, the car wouldn’t start. One of my battery terminals was severely corroded. I had the terminal and battery replaced. No further problems - until last week when I was on a dark highway and noticed the lights were flickering again. It is fairly subtle, and not noticible on lighted roads. The voltmeter is showing charging while driving. No trouble starting the car. The battery terminals are clean. Any ideas??
Usually flickering lights is related to a power problem. I’m betting you have a bad connection or a bad relay. Unfortunately on this type of problem, the best (or only) way to find and fix is through manual inspection of all components and connections. If it’s both lights that flicker together, start with the point furthest upstream where they wiring comes together. You almost need a diagram for this one. It could be anywhere from an inigition switch, relay socket, relay, power wire or accessory wire coming off your battery or junction. This one will require you rolling up your sleeves and jumping in. Good luck.
Have someone check the voltage at the battery with the engine running with a meter. But set the meter to read AC voltage. If there’s any AC voltage at the battery, one or more of the diodes in the alternator are leaking, allowing AC voltage to the battery causing the lights to flicker.
Since the alternator is an ac generator, as the engine speed increases, the ac frequency should increase, resulting in an increase in flicker rate. Do the headlights flicker quicker as engine rpm is raised?