dome lights are not turning on when opening the door

Start by checking at the dome light to see if you have twelve volts on both sides of the bulb. If you do not, we need to work back toward the fuse box. If you do, I will need to dig up a wiring diagram to see if there is a Body Computer involved. If there is, the diagnosis gets a lot more complicated.

With the key off no voltage key on 6.5 volts on each side.

Does the horn work? The horn and the interior lights are on the same fuse. If the horn works okay, the first suspect is the interior light switch, but not all vans use that. It is a dash switch that, when turned off, prevents any interior lights from turning on.

You need to have full battery voltage on one side of each interior bulb. You'll find it on both sides if all the door switches are turned off, meaning all the doors are closed. That 12-volt feed wire is the orange wire. The white wires go to ground through any of the door switches.

As shown on my diagram, some of the overhead interior lights only turn on with their individual switches, and they have their own ground circuits. If the dash switch is defective, those lights also will not work, in addition to the lights that turn on when a door is open.