My 1989 S-10 pick up digital dash board lights are out. In a recent heavy rain they came on for two days and are out again. What's wrong and how can I fix it?

Moisture problem... try blasting the ground on the frame with some wd40 maybe the wire and distributor but most importantly the cylinode switch on the side of the starter... wd40 stands for water displacement 40 th attempt.

CHECK THE PLENUM CHAMBER FOR REMAINING WATER INSIDE!!IF NO WATER FOUND THEN SORRY TO TELL U THAT BUT U NEED A NEW DASH BOARD!!!!!!THAT MEANS A TRIP TO YOUR NEAREST DEALERSHIP!!!

The moisture in the air is an obvious indication of a poor electrical connection/contact. You must inspect the ignition cap and rotor and replace if excessively worn.

you can check the plugs on the computer (ecm/pcm)

change the distributor cap by friend did the same thing and i wouldent start untill we took the distributor cap off and we seen croshin and we replaced it and it started up like a champ

Sounds as though you have an exposed electrical connection that's either getting splashed from the tires, or the moisture is creating a temporary disconnection. This can happen, but once it dries it will resume working. I would have your electrical system checked. I would also have your headlight switch checked for a possible short.

Obviously water is the cause. Make sure all hood seals and underbody splash shields are in place, check firewall main connector for security. After it rains (without driving it in rain) check floor mats inside for water. A possible windshield or dash leak is allowing water into electrical area near instrument cluster (windshield may need resealed). Lift hood and look for water on any electrical connections disconnect dry, and seal with tune up grease from parts store.
Good luck

Blown head gasket on Bank2. (Passenger Side)

I'm sure the car has seen heavy rain before without causing any problems. Did rain get inside the car or the car driven through high water? Check the fuse panel for evidence of water contamination. Look for burned fuses or corrosion. If you can't find any fuses or relays that got wet, then I would look to the ignition switch.

2006??? sorry but as far i as know you will need to return vehicle to dealer because all cars from 2005 are using encrypted software .Best advice i can offer is to wait till it dries out a bit and see what happens in case water has shorted something out