1998 full size van key switch does not return to the run position

it sounds like you fault is with the drivers side headlight or wiring.
have you up rated any of the lamps or done any removel or replacement of parts?. The headlight connection to the lamp may be faulty, even the lamp may be faulty, one of the healight or main beam wires may have been trapped or have been rubbing against the chassis. you have a direct short from the 12v to ground on the main beam and partial leakage on the normal beam. I would use a multi-meter and using the continuity buzzer start at the head light connections and put the meter across the 12v and ground if it buzzes trace the wires back to the relay and unplug the relay and buzz the 12v and ground on the connect going to the light if it doesn't buzz then buzz the 12v and ground going to the relay on the connector, if still buzzing then trace the wiring back to the light switches remove connectors and repeat as above. for best results disconnect the battery before hand. this fault maybe causing your other issues. good luck.

I agree, although the rod may be bent, or it's nylon bushings have loosened or fallen out. I am not sure if the switch is under the column cover between the steering wheel and dash, or if it's on the column up under the dash. The switch mount screws may be loose, letting the switch move "away". It could be the arm on the lock cylinder is worn or loose. I think that on a 1994 those two items are fairly easy to access. Let me know what you find!

FIRST TURN OFF RADIO.DISCONNECT THE NEGATIVE BATTERY CABLE,THEN THE POSITIVE BATTERY CABLE.WAIT 20 MINUTES. UNTIL AIRBAGS DISCHARGE.TURN THE IGNITION KEY LOCK CYLINDER TO THE RUN POSITION.REMOVE THE CENTER TRIM PANEL AND THE DRIVER SIDE KNEE BOLSTER.UNPLUG THE IGNITION SWITCH ELECTRICAL CONNECTOR AND REMOVE THE SWITCH RETAINING SCREWS. DISENGAGE THE IGNITION SWITCH FROM THE ACTUATOR PIN AND REMOVE THE SWITCH FROM THE VECHICLE.MAKE SURE THE ACTUATOR PIN SLOT IN THE NEW IGNITION SWITCH IS IN THE RUN POSITION.A NEW REPLACEMENT SWITCH WILL BE SET IN THIS POSITION.PLACE THE NEW SWITCH IN POSITION ON THE ACTUATOR PIN AND INSTALL THE RETAINING SCREWS IT MAY BE NECESSARY TO MOVE THE SWITCH BACK AND FORTH TO LINE UP THE SCREW HOLES.WHEN CENTER TRIM AND KNEE BOLSTER BACK IN PLACE.CHECK FOR PROPER OPERATION OF THE IGNITION SWITCH IN THE LOCK, START AND ACCESSORY POSITIONS.

It could be the multifunction switch (turn signal lever switch) on the column. 5 screws to get to it and change it. Three on the lower part of the column cover. 2 that hold it in place. then just unplug it and reverse the process. If they're going on and off at will like there's a demon living in the van, day and night. It's the BCM behind the fuse box (driver's floorboard).

you got a electrical problem check the switch boxes make sure there is no burn out amp.

The Immobaliser has probably gone west,

go under the drivers side of the dash RHD if LHD go for passenger side.... You will find a black box secured with 2 screws.... undo it get it out poen the box you will see 2 small relays one is start inhibit the outher ign inhibit.
just close thire contacts manualy (Bit of cardwedged in works well) thats what I did on the last one! but you culd solder across the circit and do it that way if you have the time and tools e.t.c. but card works fine O.K.?

it's located on the drivers side in front of motor,housed in large black plastic case with screws

Can you hear the fuel pump run when you cycle the key?

if you are lokking at the engine stood in front of the van the gearbox bellhousing is to the right. look down almost in the middle slightly to the right near the back the reverse light switch is screwed in from the top, it has a plug connector on it with two wires a black and a black and white if my memory recalls.hope this helps

Remove the fuse! The fuse box under the hood has the DRL (daytime running light) fuse. The underside of its lid should tell you which one. Either that, or just remove the bulbs from their sockets.
If ALL the lights (head, tail, dash,etc. are coming on all the time), then those aren't DRL's. There's a light sensor (little round black dome) on top of the dashboad in the middle front nearest the windshield. They sometimes fall down inside the dash (where it's dark!) and this triggers all the lights to come on when the ignition is on.