Outer Limits 4x4 Board

hey just wondering if anyone has had the the batt light stay on in there truck mine 24v also had been though mud etc no prob car sat 4 a week then i cleaned the engine and prob started the volts meter was showing half way with light on now its on 20 and a bit hard to start any idea on where to start looking for prob and also what are you guys using to clean alts ive heard metho but have not done it yet any help would be good thanx its a diesel if there is any diff

I would start with pulling out the plug spraying some inox in there and make sure it is plugged back in properly. Then check all the other terminals are nice and tight. Pull the alternator out and pull it to pieces to clean it properly. While its out test the rectifier plate, the regulator, brushes and bearings. Not difficult to do, any workshop manual will detail how to test an alternator properly. I rebuilt mine and replaced everything inside for way under $100. Don't forget simple stuff like checking battery terminals for tightness, hope some of this helps a little.