I also posted on another diesel site, but want to try to gather as much expertise as possible. Thank you!

Sorry this is long, but I'm desperate!!
I have read numerous threads regarding the infamous door ajar light. I have tried all of the methods that I read about, ie. WD40, I put enough WD40 on each of the switches, that I dont expect my doors to rust from the inside!!! I removed each switch, cleaned, lubricated, and ohmed each to no avail. All switches are working properly. I read alot about the GEM. I sent my VIN to Powerstrokeshop, they told me that I dont have a GEM, (my truck is a 2002 F350 7.3 CC Lariat 4x4 dually longbed), but they couldnt tell me what would control the door ajar light other than the switches, (door sensors is what they called them). Other than the the annoying door locks popping up & down, and the interior lights and cargo light staying on until I reach a certain speed, occasionally in the morning while traveling to work in the dark, I would hear a relay or something start to chatter in the dash behind the radio area. This didnt cause any trouble unless I tried to shut my lights off, then, they would flicker in unison with what ever is clicking in the dash. If I turned the truck off, the headlights and the clicking would stop. Well I noticed something this weekend comming home from vacation. When I would travel through a tunnel where the light is diminished, my headlights would start flickering and the clicking would commence, if I turned my headlights on, they would not flicker, but the clicking continued for approx. 10 minutes after I was back into the sunlight. After that the clicking would stop and I could turn my headlights off. I am sure they are related I just dont know how or what controlls the door ajar light, since I dont have a GEM. Does anyone have any experience or ideas about what I could test? I did test for any DTC with AE and had none. Thanks in advance for any info!!!!

 

You spray the latch, not the switch... The open part on the inside of the door that latches to the stud in the door frame. Or is that what you're calling the "switch"?? Mine did this and I used crc silicone lube -- worked right away.

 

yeah, I removed each switch, cleaned, lubricated, ohmed, cycled hundreds of times, I even jumpered the wires at the connector, and none of that worked!?

 

You have a 2002 truck I see, here this might help.
https://www.ford-trucks.com/forums/4...?highlight=VSM

 

Sounds kind of like a relay. Since so many things are wired together you might try removing one relay at a time until you find which one makes the door light go out. If you find one, swap it with one you can do without for a short time and take it for a spin to see if that fixes your problem.

 

I had almost the same problem with a 98 f150 thatI used to have. I replaced both door sensors. It worked for a while then started again. I ended up doingjust as Chris said and replaced the relay and that fixed the problem.