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Headlight problem

when all the fuses and relays are in place, the left bulb is out and the right bulb is on, but whenever i remove the fuse or relay for the right bulb, both bulbs become dim. it seems to me that power is getting to both bulbs. how else could they both be on? so why doesnt my left headlight work?

Year, make, and model, please.

All vehicles are not the same.

2003 Subaru Baja

It sounds like the left fuse may be blown. Try reversing the fuse positions to see if that changes things. If it does then the fuse is bad. Due to the design of the lighting system things act like you describe when power is lost on one side. Another possibility is the low beam light on the left side may be bad.

I have tried reversing the fuses, and the result remains the same. The bulb is brand new.

Check to see if voltage is getting to the left side light. You might also try reversing the headlight relays. The left one may be bad.

Switching the relays didn’t change anything. I may have to bite the bullet and take it to gulp the dealership.

Can you switch the bulbs? And be careful not to touch them with your fingers. Just because they’re new, doesn’t mean they’re good.

Failing that, use a voltmeter, and see if you have power to the connector. Actually, do that first. Then try swapping the bulbs.


By all means, don’t take it to the dealership yet. I’m looking at the wiring diagram for your car. This kind of problem sometimes will show up as a result of a bad ground. You didn’t say if your flash to pass works normally? Do your running lights all work normally? I would remove and reset the connectors on your left headlight. Your problem could be in your combination switch (where you turn on your lights) or the daytime running light control module it looks like power from your headlights either comes from or goes to there. I’d find that and reset that connector. It might come down to you pulling all plugs and start checking for power using the schematic I’m trying to attach.

It may seem that power is getting to the left side due to seeing the dim glow, but it really isn’t. Voltage is back feeding to it and that causes the dim glow. Verify voltage is getting passed the left side relay and if it is then the trouble is most likely in the wire connection between the relay and the bulb.

This is all very helpfull, thank you. I do a lot of night driving so I need to get on this. Once I procure a battery tester, i can test to see if any actual power is moving through the switches

You can get a cheapy volt meter from someplace like Harbor Freight, for ~$5. It’s not great, and I wouldn’t trust it down to any decimal places, but for basic 2v vs 12v, it should work just fine.