WD-40 attracts dust since it is oily, Silicone spray lubricant dries dry. I also spray silicone spray lubricant on a rag and then wipe the rag on all door weatherstripping. This keeps the weatherstripping treated so it doesnt dry rot and also keeps them doors from freezing shut when it gets cold outside.
On my 1998 there are 4 contacts on the door jamb and 4 contacts on the door. Lightly sand off all corrosion and apply some Dielectric grease to the jamb and door contacts. This is usually the #1 reason the sliding doors malfunction due to poor electrical contact.
This will keep the contacts from getting corroded again and will keep the electrical contacts working. I have to do this every now and then cause somebody (cough, Wife) like to lean against the Jamb while loading the Van up.