I hope this isn't old news here but a bunch of searching leads me to believe it isn't.

For some background, every couple years this truck shows "lamp out" on the dash and the left front low beam doesn't work. In the past, I've replaced the FCM and this has fixed the problem, for a couple years at least. Well, buying that $230 part gets old and I finally found a different solution.

When you plug in the FCM and press it all the way home by hand, there is still about a 1/16 inch gap between the side of the plastic fuse box and the aluminum flange around FCM (where the four screws go through). Apparently, clamping down the screws and closing this gap causes the lamp out / front low beam problem. The fix simply involves unplugging the FCM, plugging it back in, and putting some type of shim in the gap so the screws can be clamped down without closing that 1/16 inch gap. That's it!

To be fair, it hasn't been a very good test yet because I did this only a couple weeks ago. But it's working so far! Fingers crossed.

 

Silly question, but what is the FCM and exactly where does it live? I've had a Lamp Out light for about three years. It started when a lowbeam headlight went out, but I replaced it and it's remained on ever since. I've also replaced every other bulb on the entire truck and it still won't go away.

 

It must have multiple jobs, but all I know is that it's involved with the function of the headlights. In my truck, there is a plastic box that holds the fuses on the driver sided of the engine bay. The FCM is attached to the side of this box. You have to get the fuse box up and sideways to get access to it.

From my reading here, since all your lights work, I'd guess your problem could be the circuit board behind the taillights. I don't remember all the details but there are some threads where they discuss this circuit board. IIRC, it gets corroded and needs a cleaning and some dielectric grease when reassembling.

 

Behind the taillights? Interesting. I'll have to pull one out and have a look around. I've had to do a half dozen bulb changes back there over the years, so maybe some moisture got in there.

Thanks!

Rob

 

No problem! Before going in, you might want to do some quick searching here. My memory isn't great on this one. I can't remember if there is a circuit board behind both tail lights or just one. I ruled it out as my problem and didn't read very carefully.

 

On my 2003 it was the left side...I've seen numerous references to the left being faulty on others also......Ben