Google "chevy wiper delay board". That board is always the trouble.
The motor is usually good but the boards on the pick-ups and vans are infamous for failure. The solder joints corrode or were cold from the get-go.
The Chilton book will not be much use to you. That board is located on the wiper motor itself. On pick-ups it's out under the hood but on vans the wiper motor is located up under the dash on the inside of the firewall!!! It can't be reached from underneath on the '90's and later vans.
It is very tough to reach! My best advice would be to buy a replacement board first to have it in hand for reference, relax (remain calm) and plan on removing the cluster, radio, headlight switch, unbolt and lower the steering column slightly, remove the heater/AC controls, the dash cover and the main crossing air duct. You can then push the wiring harness back enough to see the motor. The board looks like a cover with the wires attached and can be removed with the motor in place. It's held on by some small Torx screws that you will need a socket for because of the limited space. (You may be able to leave the heater controls connected but you will at least have to unscrew it and move it aside). If it's your first time I suggest taking pictures as you go.
I always use a very (very) thin line of RTV sealer on the new boards edges to help it seal although it's not that important in a van.