Ok heres the deal. I have an 89 240 DL and I'm having trouble with the brake lights related with my headlights. When the headlights are turned off everything works fine. As soon as I turn the headlights on the brake lights stay on at all times with the exception of the 3rd light. I have no idea what the problem is. Both printed boards are fairly new, the brake light trigger switch has been adjusted, the fuses are fine, does anybody have any ideas?

 

Now that's kind of a brain teaser. Has anyone done any kind of wiring on your car lately, like a radio, alarm, fog lights, or anything else? It sure sounds like some wires are crossed or have been tapped into that shouldn't have been. Or did this just start happening out of the blue with nothing at all being changed or added to your car?

 

Thanks for the reply Jet. Yeah, this problem started completely out of the blue. Electically I'm running completely stock. I'm guessing I have a crossed or melted wire somewhere, but I'm wondering what else it could be.

 

You say the curcuit boards on your tail lights are not that old. Have you checked them to see if any melting has occured? I ask because I bought a set of tail lamps from lampsandlenses.com and they installed the wrong wattage bulbs in 2 of my sockets, that caused a melt down of the sockets and all kinds of problems. I was able to clean up the sockets and install the correct wattage bulbs with no further problems. I would look at those curcuit boards closely and the bulb sockets to see if anything has started melting.

 

Also check the Bulb Failure relay.

 

I checked both boards tonight and they are both free of any type of burn marks. I'm not sure how to verify that the bulb failure relay is working properly without having a replacement. Would it be worth a shot to pick one up from a junk yard?

 

Yes it will be worth a shot.
Give it a try.
Re look really close. Look for cracks in the solder.

 

So after trying almost everything I finally figured out the problem. Many months ago I had my car to the mechanic for several issues, one of which was a burnt circuit board. The mechanic replaced the board and all was well, or so I thought. I was unaware that the lights were not functioning properly for some time until a friend was following my car. After replacing the bulb failure relay, cleaning and checking the grounds, cleaning and checking the bulb holders, and examining the bulbs again and again........I finally realized what happened. The mechanic put single filament bulbs in the brake light positions instead of double filament. After all the crap I tried all the car needed was 5 bucks worth of lightbulbs.

The moral of the story................look at the obvious stuff really closely before getting excited.