My 2004 S came back from college with one low beam headlight out. Thanks to YouTube, replacing the bulb is a snap - literally. Unfortunately, the new bulb did not resolve this. Tried two new bulbs, the one that worked from the other side, and each one upside down and right side up. No dice. Fuse appears to be for both headlights and wasn't blown. Before trying to shoot wires, any ideas? TIA

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Take a close look at the connector to ensure the metal contacts are in place. If all is well use a multimeter to check voltage at the connector contacts. I assume you've already checked the fuse.

 

I've had folks bring GEN1 cars to me with one light out. Inside the housing between where the harness connects and the bulb socket is a set of 'internal' wires. With the bulbs out you can see this. A couple of times I've found the insulation on these wires GONE ... cooked off. What remained was brittle and would fall away at the slightest touch. Short of taking apart the assemble which is not built to be taken apart I could find no way to attack these wires ... if they touch each other a light is shorted out .... In each case the owner ended up buying replacement light housings ..... When I found this on one side I'd check the other and the insulation was gone there too ... but nothing had touched/shorted yet. (dealer had no solution other than new housings either)

I SUSPECT this to be more of an issue when the owner (previous owner) had run a hotter/brighter bulb and created an oven ....

 

Checked the integrity of the connector and bent the three contact points back toward the center in case they were not making contact. Also, the fuse is OK. And as near as I can tell it is a single fuse for both lights, so since one still works that kinda confirms it. Thanks for your reply.

 

Thanks Capt. The insulation on the two wires coming off of the connector appear to be in tact, no visible breaks or brittleness, at least for as far as I can see up into the socket well. Besides, if there were insulation breaks and the two wires touched wouldn't that have blown the fuse?

I'll try and disconnect the harness next and see how far I can get from that side to check those wires. Suspect you are correct that there is no easy solution. Really hoping not to have to buy two whole new assembly's.

Original owner, pretty sure I didn't change the low beams when I upgraded the high beams, but it has been 16 years+ !

Thanks for your insight.

 

I had the same issue on my '03. If the bulb and external ballast are OK- and you could switch ballasts to test, then the culprit is likely the ignitor. On early models you'd have to disassemble the light itself by cooking in an oven to softer the light's seal- search for the Joey Mod. I couldn't do that so I ended up with a whole brand new light- over $400 years ago on Amazon. The replacement has been perfect for well over ten years which makes the initial cost a little less painful. You probably could get a used one from a supplier like Almag auto parts that is on this site regularly. Give the ballast switch a try- maybe you'll be luckier than I was!

 

If you haven't already, use a volt meter to ensure you are getting 12v to the light socket. I had the same issue mentioned above. Prior to seeing the wires were bad, I was getting 12v at the socket to the light housing, and only 3v at the light itself. I ended up getting a set of projectors and subsequently putting LEDs in it for an even brighter light output.

 

Thanks BRGPA and David. I'm out of town until tomorrow or Thursday. Since I first posted, I have found that the wiring harness for the guilty light was routed around the bracket on the side of the assembly and not under the bracket like the other side. There is some evidence of wear on that bundle but no obvious bare wires exposed. So plan A is to unwrap that bundle and check for a compromised wire. Next I will swap the ballasts as suggested. There are replacement assemblies available for $150 so that might be the final solution. Thanks again for posting.

 

If you have the halogens then my test will work for you. If you have the HIDs then the voltage at the light will be different. Also, halogens do not have a ballast to swap so if there is any question as to the bulb type, that is something to look for.

 

Update: Dissected the mis-routed wire bundle but didn't find any individual wires compromised. Swapped the ballasts (an easy task, thankfully) and indeed one was bad. Opted for a new one from E-Bay even tho shipping time was twice as long.
Thanks again everyone for your help. Great resource !

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