Ok I have a 2003 7.3 f-250.
First replaced the cluster, old cluster showed normal issues. Door ajar light is on computer shows both front doors open. Did the wd40 deal didn't work took the door apart replaced the sensor didn't work. The only thing I have left to replace is the GEM. Anyone have any other options? Can I test it?

 

had the same problem but I lucked out with the wd40 trick...supposedly the problem can manifest itself due to incomplete grounds. My old OBS had the similar problem to the door ajar but was the dome light coming on with brake pressure or just bumps in the road. That cause is similar to what I've read with the door ajar problem which I had but was able to resolve with the wd40. the OBS issue was cured by running a ground to the cab chassis. The engine department is cool but the rust affects the cab scenarios.