Battery was low, glow plugs lights worked but it just clicked when trying to start. I looked at terminals and replaced the positive cable end ( I did hit frame and got small spark) because of corrosion. When it looked to have a good charge I turned ignition key, glow plug lights came on, turned the ignition switch, then nothing, went dark. I jumped the negative, to see if I might have a bad ground, but nothing. I don't know where to start.