I have a 2001 f-250 that has dome lights that work on occasion. Mostly don't work. The inside dash dimmer won't turn them on. And they will sometimes work with the rear doors opening. Not the front(4 doors). The cargo light comes on all the time. So I don't know where to start chasing. Any ideas?

 

Pull and check the door switches and wires. Check the bulbs n sockets too. Also grounds are your friend my friend. Clean and tight is the rule on a negative ground system such as our trucks have.

 

Ok, where are the door switches? It's not like my old 150 with push buttons in the door jams

 

The "Door Open Warning Light Switches" are located in the latch in the door. Just had to replace one on the driver's door on my month old '04 F-250 that was keeping the cargo light on. Somebody had pulled the dome light bulbs to keep them from staying on. And the kicker: you have to pull the latch to change it.

 

Here is a picture of the little bugger in question. It's in the bottom of the latch.

 

Oh crud, so the door has to come off?

 

No, just the inner part of the door. then access is possible through the cut outs in the door.
First I would try the old trick off spraying a bunch of WD 40 or something like that in to the latch it may just be dirty.
There is an other possibility that it has nothing to do with the door switch at all.
I had a intermittent dome light issue that was caused by the Instrument cluster, the dome light would start blinking at any hour when the truck was sitting.
You may want to monitor that to see if it happens when the truck is off.
First I would try the WD 40, see if it stops.

here are some of the problems cause by a faulty Instrument cluster, Gauge problems and a myriad of other problems all originate from the instrument cluster, they can include, Issues with, Dome light, Radio, TCB, VVS, Odometer/ Speedometer, FALSE Error codes, Drain batteries, Damage your FICM. You will not get error codes with a faulty instrument cluster.

 

Well just checking to see if my "door adjar" light comes on, it appears all my door sensors are working. And I'm not noticing any of the other issues.

 

After talking to the service rep at the dealer, was pretty sure that it was a switch. Let them run a scan to find out which one; was worth the $50 to keep from pulling all four door panels! Might be some thing to keep in mind. Thankfully don't have any cluster issues, and hope it stays that way!

 

My thought on the problem is this. If all four doors have problems then it can't be the switches, I doubt that all four switches will malfunction at the same time. So the fault must be elsewhere if the doors operate the dome light intermittently then the fault is in the circuit that drive the on/off/time delay that operates the dome light. That circuit is driven by a relay, unfortunately the relay is part of the instrument cluster. Search for instrument cluster repair and give the folks a call talk to them and see what they say.
If you checked the bulbs, and the fuses. Then I would give them a call. Do a continuity test on the bulb sometimes the filament will look ok but when tested it turns out not to be the case.
An other way to check if you have any problems is to check the battery reading after you turn the truck off at night then take a new reading in the morning to see if you had a drop in voltage.
My dome light started to blink at night the first time I noticed it was a 1:30am I just happen to wake up and look out the window at the right time.