If the horn doesn't work either, then it's the clockspring. The clockspring in the steering wheel allows the wheel to turn while still maintaining an electrical connection with the horn, seat belts, and passenger seat weight sensor (so the air bag system knows the difference between a 3 year old and a 30 year old in the seat).
Make sure nothing is interfering with the seat belt switch, like a dime or a paper clip. The seat belt may latch and click like normal, but if there is anything down in there interfering with the switch you'll get the restraint dash lights. Also make sure the wiring from that switch, like under the seat, hasn't been pulled or damaged.
One thing to try is. . .
With the van off, turn the key to RUN, but don't start it up. Turn the emergency flashers on for 4 or 5 flashes, then turn the flashers off. Then turn they key OFF and pull the key out. Wait 15 seconds and put the key back in and start it up like normal. That will usually clear the blinking odometer in most vehicles. Worth a shot.
Finally, disconnect the negative battery cable for a full 10 minutes to clear out the computer (making sure any aux or house battery is not also connected).
The most common reasons for restraint lights are, in order, the clockspring, something interfering with the seat belt switch, damaged wiring, bad passenger seat weight sensor. Beyond that you'll need to have the codes read to see what the more unusual causes might be.
