Problems with the battery light of a golf MK III

Hi, I have a problem with my Golf. The battery light won't come on, even when I ground the alternator cable directly. I've been told it could be the ignition switch. Also, the oil pressure light won't turn off.
If anyone knows anything, I'd appreciate your help.

Check the cables going to the battery posts; they're most likely heavily corroded. Clean them and, if necessary, replace the terminals. Regarding the oil pressure light, you should use a pressure gauge to check if the engine has oil pressure. If it does, then it's just the oil pressure sensor, which costs around $100 pesos.

Hi, that was the first thing I had to do, because they were in terrible shape, but it's still the same. Since the pressure regulator is cheap, I'll buy one of those. I've already left it running for a while and nothing happens to it; it doesn't overheat or anything, it sounds fine, so I'll buy it. Thanks

Well, I've solved the problem; it was the alternator. But now it's hard to start, and I've replaced all the glow plugs. It could be the pressure valve, but I'm not familiar with the rotary pump, and I don't know where the valve is located. Can someone tell me?

Did you try changing all the filters? It could also be that the battery is almost dead and needs charging. You can charge it with a charger or take a fairly long drive if you don't have one, so the alternator can charge it.