check that the terminals are not loose (for what you say that the warning light turns on and then it turns off it may be that or the loose alternator etc etc) start by checking the cables and terminals of the battery !!! As for the 300km you must do, I don't think it's a problem while the engine is running! then if you take the truck to the mechanic if you don't get up to it regards!!!
Hello the terminals are good and clean now the light turned on and does not turn off! Tomorrow I take the electrician and comment
Well group visit the electrician tested and effectively does not charge! Given that we were at 9am Saturday. I advise charging a battery and continue traveling to my trusted workshop. Because if you disassembled and did not get a replacement, you had to wait until Monday. I count that I had the truck loaded and of course during the day and without lights on, I arrived at bs.as. I did 270 km if problem tomorrow should allow me to reach a workshop!