2002 X-Type 2.5L
The low beam bulb is intermittent on the passenger side.

The driver's-side low beam bulb works fine.

All other lights work fine: High beam on both sides, fog lights, turn signals, etc.

I replaced the bulb, but it still works intermittently.

Any suggestions what to try next?

E.g., do the driver's and passenger's low beams have separate relays - perhaps the passenger relay is going bad?

Thanks.

 

DW, both of the low beams use a common relay, but have separate fuses for the bulbs. So, you can rule out the relay. Odds are, you are looking at a bad base for the bulb. I would replace the bulb base and go from there. These are known for being a pain in our cars.

If you don't want to just start randomly replacing stuff, then the next best thing that I could tell you to do is to create a set of multimeter leads that are fairly long (ie, need to run from the headlight assembly to inside the passenger cabin, should have alligator clips on the one end being connected inside the headlight assembly). Then you can connect up the leads to the wires for the low beams and drive around a little bit with a passenger in the car. They can watch the multimeter as you hit bumps to make the light flicker. if the multimeter is constant, then that confirms a bad base. If the multimeter flickers, then you have a wiring issue. Write me and I will give you some other checks to do.

 

Thermo: Thanks for the suggestion to check the bulb base, and set-up test wires / alligator clips. I didn't know these cars had problems with the bulb base.

I'll also try wiggling the base with the low beams on and see if that makes the bulb flicker.

Since there's separate fuses for left and right low beams, I'm curious why you didn't suggest I check the fuse. Is that because the passenger side fuse also powers the high beams, fog lights, & turn signal, which work fine?

Thanks for your advise.

dwclapp

 

DW, normally when a fuse goes bad, it will either completely open, therefore light will not work at all or the fuse will develop a high resistance inside of it and cause the light to go dim. What you are describing is almost like a switch going on and off. Besides, doing the multimeter check, as long as you are seeing over 14.0 VDC at the bulb, you know the fuse is good.

As for the bases going bad, a recent experience with a fellow members Jag that I worked on, we had 2 bulb bases go bad at the same time. The bulbs tend to get really warm and it will cause the bases to become brittle.