Hey everyone. Did a search already and not finding an answer. Have a strange issue. All lights work fine but the headlights vary in brightness. No other lights including fogs, interior, nor rears seem to change at all. What's the right troubleshooting routine? I do not have a voltmeter gauge in the car.

Try a few easy things first:

1) Check the fuses to make sure the connections are free of corrosion.
2) Switch the headlight bulbs and see if the same side stays dim or the same bulb. Clean all electrical connections while you’re in there.
-if the same bulb- Replace.
3) if the same side remains dim, check that the 3 wires are in exactly the same orientation on both side. I’ve seen where the ground is in the wrong tab and the light grounds through the other filament and still works, but is much dimmer.
4) check & clean ground to body connections on both sides.

After that, you’ll need to trace the wires back to find breaks, corrosion, etc. and/or test the switch.
Hope that helps!

Tom

Thanks Tom! This behavior is happening with both headlights equally and at the same time. Does that change the possible causes or debug?

Are you saying the headlights actively fluctuate in brightness, in tandem? Like a candle flickering? How fast is the fluctuation? Is it better/worse with the car running vs just on battery power?

Can you provide a little more detail of the behavior? You will eventually need a volt-ohm meter (VOM), so now may be a good time to buy one if you don’t already own one.

All the above steps are still valid, in my opinion. You’re looking for the reason why enough power is not coming through clean. Could be resistance in the circuit (power and/or ground), or power supply (battery, alternator, voltage regulator).

Another thing to try: Make sure the battery connections are clean and try the headlights with jumper cables attached to another vehicle, or to a known good battery, with car running and not.

Yep fluctuations are in tandem but ONLY the headlights are doing it, not the interior lights or any others that i can tell. Thinking about getting a center console anyway qhen i freshen the carpet and seats this winter...

Will run through your suggestions this week for sure and come back here with results.