The low beam headlights on my 2002 X-Type have always been about as bright as parking lights on most cars. I have also experienced headlight problems over the years, including the melting headlight sockets and, more recently, a headlight that kept shorting out and blowing its fuse. Last night, while driving on a very dark road, my X-Type demonstrated its newest headlight trick. The lights would go from normal intensity to very dim (barely able to see the road) for a few seconds, then return. This cycle repeated continuously on my 30-mile drive. There was nothing that appeared to trigger this behavior, and nothing else in the electrical system seemed to be affected. (For example, the dash lights did not dim.) My battery was replaced about a month ago, and I do not suspect an alternator problem. I experimented and found that this behavior affected both the high and low beams. Since most problems seem to affect other owners, I am wondering if anybody else has experienced this and found a solution.

 

My initial thought is that you have a bad ground connection. I would start with checking the condition of the ground connection on the bulbs. There is also a connection to ground behind the headlight attached to the body. Finally i would look at the condition of the wiring from the fuse box to the light plug. Also, check that the plug connection to the light is in good condition

 

plpelland, from what you are describing, it is sounding like your headlight internals are broken and they are bouncing around inside. Because you talk about the melted headlight harness, this tells me that you have the halogen headlight system.

It may be a wiring issue, but this would lead me back to having an issue with the fuse box rather than the wiring itself. Something that you can try is this: open up the hood of your car and access the fuse box. Locate relays R9 (low beam relay) and R1 (wiper replay) and swap their positions. Do your low beams seem to work better (ie, do not dim) and your wipers may seem to have issues maintaining speed? If so, buy a new relay and replace relay R1.

You can do the same thing with the high beams by swapping relays R15 (high beam/fog light relay) and R21 (battery saver relay). This may result in your high beams working great but your interior lights and whatnot starting to act funny. If you see this, replace the relay in the R21 spot.

Lets see what you have at this point and then we can dive into things further. On a side note, how are you with using a multimeter?

 

Me mechanic checked the voltage on the battery today and actually found it to be higher than it should be. He seemed baffled and thought that the alternator may be the culprit, but this would not explain why ONLY the headlights are affected, nothing else that is noticeable in the electrical system. If it was a bad ground or thermo, wouldn’t it affect only one bulb? This dimming affects both bulbs simultaneously, and both high and low beams. I think that a bad ground would also be more likely to cause very sudden changes in the brightness, whereas these (both the dimming and the brightening) seem more gradual (taking a second or longer).

I hope that this information sheds more light on the problem. (Yes, I know, a very bad pun.)

 

plpelland, if your battery ground is the source of the issues, then it would possibly explain everything. The other components of the car are not necessarily driven at a full 12VDC (ie, fuel pump is pulsed on and off to maintain a pressure, dash lights are run through a pulsing circuit to control how bright they are, etc). So, you may not be noticing the difference as much as you are with the headlights.

Something you may want to try is when you start the car, press and hold the TRIP button on the end of the turn signal stalk as you turn the key. Once the car is up and running, continue to hold the TRIP button down until you see the message center read "Engineering TEST" (or something to that effect). Now, repeatedly press the TRIP button until you see the message center say "BATT XX.X" (where XX.X is going to be a value around 13.7). This will take about 35 presses of the TRIP button. Yes, the instrument cluster is going to be saying all sorts of stuff and may do a few funny things (ie, turn on all the lights, cycle all the gauges from min to max and back, etc). This is normal. But, what you want to watch for is if your lights start doing funny things, is the number that you are seeing on your message center changing with the lights (ie, goes up when the lights are bright, goes down when the lights are dim). This will help prove a bad ground wire.

Another check that you can do is take the car for a drive and turn on everything electrical that you can (both seat heaters, rear defroster, headlights, dash fan on high). Drive at highway speeds for say 10 minutes. Turn off everything just before you can pull off and open the hood. Now, remove the cover off of the battery and put your hand near the battery posts. Are they warm (like most of the other things under the hood) or are they HOT!!!!!! If they are hot, then this would be a sign of a bad cable. Replace that and then see what you have.

 

Thanks, Thermo. This makes a great deal of sense. I will check this out today.