On my 1990 van, the power door locks are all of a sudden keep recyling from
locked to unloacked.

When I put the key in , I have to hurry up and open the door or it will
relock itself.

As long as the door is open the loack keeps locking and unlocking.
Once I close the door it stops, but the door is locked.

Any suggestions of where I should start.

Thanks