1989 Toyota Van Dash lights on

I need more than "checked everything" to work with. Give me some test results to analyze. What did you test and what did you find? What do you have for battery voltage with the engine running?

I checked the radiator fluid level. I also replaced the alternator because it was not charging. For the brake light I checked the brake fluid reservoir and its fine. Im getting 14.13 volts when the van is running.

14.13 volts is perfect, . . . right between 13.75 and 14.75 volts, but that's just the first part of the test. Next you'll need a professional load tester to test the output current. If your generator has a defective diode, you will only be able to get exactly one third of the rated current, and "ripple" voltage will be very high. 30 amps from the common 90 amp generator isn't enough to run the entire electrical system under all conditions. That can be enough to turn on the warning light.