get a new dimmer switch on Amazon for cheap and that will solve the problem

 

I think I know what your problem is. My 2006 Lariat had a problem with the dome lights and cargo lights working intermittently. I tried all kinds of stuff and finally had my buddy help me who is an electrical engineer. It turned out to be a bad circuit board in the gauge cluster.





It's very easy to remove the surround that covers the cluster. Once that's off simply reach in a gently move the board located above the coolant temp gauge.


Here's my cluster part number





In my case I've just been living with the issue because it doesn't appear to be an easy fix. The cluster will either need to be replaced of go into a shop that does that work.

 

So if my dome/cargo light comes on while driving down the road, I can give the dash a good whack and the lights will go off, but I can't fix the problem without buying a new cluster? Certainly something must be happening otherwise the lights would stay on when I give it a whack.

 

I ended up having to replace the instrument cluster. Fixed it. About 600-700 or less if you know someone

 

Probably yes, you'll need a new cluster. I encourage you to remove the surround over the cluster. Then reach in and gently move the circuit board while watching your lights. In my case, deflecting the board caused my lights to work normally. This might be what's known as a "cold solder joint" which can usually be repaired but in this case I cannot access the board because of the way it's constructed.


Instead of being pissed you should be happy that I've done all the leg work for you. I spent many hours running down the cause.

 

Symptom: interior lights come on and off while driving. Brake idiot light may also illuminate although the warning is false no brake problem exists.

Cause: Poor connection ( cold solder joint) on printed circuit board inside of dash cluster

Repair: Remove cluster from vehicle, open cluster, remove indicator needs from all dials, remove printed circuit board from cluster. Re-melt all soldered pins on tach side of circuit board ( left side when facing cluster installed in dash. About 20 points total, but both sides of the board (front and back) must be done unless u are able to determine which contact has gone bad. Diagrams, detailed instructions etc available on this forum or pm me.

Difficulty level: easy if u can handle a soldering gun. Indicator needles require a spot of crazy glue on reassembly.

 

I am having this same issue on my 2004 F150 Lariat Crew Cab. I took out the gauge cluster this weekend and didn't see any cold solder joints. Do you know which pins exactly control the cargo/dome lights on the board? Any additional information you can provide would be great. My dome light only work when I move the slider on the rear dome light to on. Then only the rear dome light turns on (not the front 2 map lights) The front 2 map lights turn on if and only if they are clicked on. The cargo light will not work at all. The dimmer wheel dims the instrument lights but doesn't turn on the dome or cargo lights even when clicked up. I replaced the headlight/dimmer switch but it still doesn't work.

 

Edit: wasn’t the fuse box like I thought, had to check the original post. Like I stated above had to replace the instrument cluster

 

Looking for wiring diagram for Instrument Cluster Connectors

I had same problem for years with Dome Light coming on randomly, I just fixed it by turning down dimmer switch to off. However yesterday the Instrument Cluster stopped working along with radio, power windows and interior lights. Before I take apart Instrument Cluster to check cold solder joints on it I want to make sure I have good power coming into the IC and continuity at the other connector. Can anyone help me out with a picture of wiring diagram for the two connections that go into the IC. This way I can hook up my volt meter and check the power and then check the continuity. If this is all good then I know it's probably the IC and not the door switch or a bad wire.

At first I just though a fuse blew but when I replace it and then connected the IC it immediately blew.

Thanks,
A Newbie
-----------------------------------------------------------------UPDATE----------------------------------------------------------------------------------------------
Used a voltage meter to test the cold solder connections on IC and two were bad. After repairing the connections Fuse #21(15 amp) still kept blowing. I unplugged light switch/dimmer and blew again. Then disconnected overhead console dome light and everything worked again except for display lights on IC. Replaced that fuse and then looked close at overhead console dome light. One tracer broke free from plastic housing in two spots and was touching another tracer. Easy fix after that. Thanks for this forum; saved me a lot of money.

 

My 2008 has the exact symptoms, but the interior lights only come on when I first get moving, then they're done until the next trip. The brake light has been intermittent for years. My solution has been to turn the dimmer switch to off when I shut the truck down to prevent them from coming on at night. I've found my battery dead a few times in the morning and I suspect those lights were coming on. My soldering skills aren't good enough to work on a circuit board so I may have to replace the IC. If it's too expensive, I may just keep doing what I'm doing. I appreciate all the info in this thread, it was certainly a mysterious problem before I read this, Thanks everyone!