My S type responds to 'close' signal from the fob by locking and then unlocking all doors and boot . Same thing happens if I use the key in the door.
Does this mean that my security system electronics have failed or is there something preventing the locks from remaining closed?
Any help appreciated.

Kendojag

 

Check that all 4 door latches are closing at the same time and the locking pulls engage If one fails it will do as you describe. Sometimes the faulty one will vibrate real quick or even just hum

 

Thanks scottjh9, your answer was right on the button. Front passenger Paul had not come back to full open position and did not move when locking attempted. Cleaned between paul and handle and used WD40 on hinge points on all four locks - doors lock perfectly now.
Thank you again.

 

Excellent. Glad to help. All four of mine have failed over the last five years. The fronts are not too bad. The rears are a little more involved because the quarter windows has to be removed. I am talking about the latch itself that has the plug ins. I always use new latches because you only want to do it once because of door panel removal and plastic parts potential breakage