Alternator Light On

[armkb]

Have a 1984 300SD...today adjusted the valves...all were tight. Runs quieter now with somewhat more response. Cleaned the motor with engine cleaner and hot water...no problems.
Then drained coolant and added a radiator flush and started the engine...now have the alternator light on. Checked the usual connections...found the junction box next to the alternator on the fender well was wet and somewhat corroded. Took it all apart and used some electrical grease on the connections. Still have the light on. Checked the voltage to the battery with the engine running...only getting battery voltage at around 12.5 volts and dropping.
What could I have done. I did get some coolant on the alternator when I pulled the heater hose off next to the alternator. Could I have shorted the alternator? Any suggestions?