Hi my 1998 conversion van (from starcraft) since I own this van (3 years) and always had intermittent problems with my power lock doors. Here's the problem in detail. When it's not working it's always the same, the problem is on all 4 doors. All the time, never had a time when only one door wasn'nt working. Something new lately, 100% not working now, and also noticed when attempting to use door lock button (ether door side) the roof light will light up ! Just like if the door lock switch was the roof light switch. I made a few checks, but my knowlage is limited. Thank you for your help

 

The current travels through in series, I suspect corrosion, the one in my rear door is responsible for this, I take it out, bang it on the bumper and after reinstall it's good for a little while longer, the switches aren't cheap, but you can try replacing them, ceiling light issue could be a bad ground.

 

Thank you maple, corrosion could be, indeed a possible cause, as this van had lots of corroded connectors, wire...and body when I purchased it. I will take a look at the rear door. Thank you for your reply.