88 D250 74K miles that's been sitting for years. Belongs to family member. Got it to run again. But brakes are spongy and barely existent. Brake light comes on message center. When it was parked years ago, brakes were fine. Where should I start looking to remedy the problem?

 

Check for fluid leaks. Really wouldn't hurt to flush the entire system, and clean all the old fluid out.

 

Will do, probably good idea to flush!. Another question, what does a brake light on message mean? In other words, what triggers the light to come on? And is it a general "dummy" light or does it mean a few specific things?

 

Depending on what options your truck has, it might be as innocuous as low brake fluid, or, it could be that one circuit has failed, and the light comes on to let you know the proportioning valve is out of position. (It tries to block off the circuit that has failed. It sometimes works.) If the light just comes on for a bit while you are stepping on the pedal, it might just be a bit of air in the system.

 

Fluid flush first. That way you can purge any air as well as look at the fluid. I've run into spongy pedals on 80's Dodges and it was a stuck rear wheel cylinder. If the truck has been sitting, I'd be suspicious of all the rubber parts considering it's age.