Cadillac Repair: 93 Eldorado No Start, cadillac eldorado, starter solenoid

Question
1993 Cadillac Eldorado, 4.9L, 167k miles. Driven daily, approximately 20k miles per year.

15% of the time, Car will start normally.

85% of the time, Car will NOT start unless I open the driver's door.  When key is inserted into the ignition and put into "On" position, lights illuminate and all other electrical appears normal.  When key is moved to "Start" position, car does not crank/turnover...no sound of starter, solenoid or relay.  Corrective measure has been to put key in "off" position, open driver door, then turn the key to "Start" position and car starts normally.  I have also started the car by opening the driver door while the key is in the "start" position.  These procedures ALWAYS work and the car starts and drives normally.  This problem and corrective procedures have been present for about the last 30-45 days.

There are no codes in the computer (via the off/Warm procedure).

Any ideas of what may be causing this electrical gremlin would be appreciated.

Answer
Inside the door is a micro-switch for the anti-theft system and most likely the wire for the micro-switch is either shorting out on the door latch when it's in the closed position OR there is a broken wire within the wire loom boot that goes from the front of the door into the underside of the dash. I have seen both.

So what it is doing is locking out the ignition relay thus preventing the car from starting. You will have to pull the door panel and inspect the wire.