We have a Chrysler grand voyager 2.8 the oil pressure switch and oil filter has been changed but the light still comes on after a short distance any idea's what it can be

SOURCE: 2007 chrysler grand voyager the

Take the van in and have them put a mechanical guage on your engine to check the oil pressure. It's possible the oil pump is not working properly and a mechanical guage would confirm or deny that as the problem. It's also possible there is a loose wire connection or possibly chaffed insulation letting it ground out. This would cause your problem as well.
Does it only do it when you are slowing down and starting off or maybe on a hard corner? If so it's likely only the oil moving around in the oil pan causing it to momentarily lose contact with the oil pump pickup tube. This is more of an annoyance than a problem. Hope this helps.