My BMW e46 instrument cluster suddenly stop working, I have tested the capacitors and all seems fine, connecting to the car I tested for V at LM2596S, no input voltage,LM2596S I m suspecting the component with the marking S4 2B.component S4 Can someone help to identify the component please, is that a TVS or diode?
Its a Schottky diode from General Semiconductor (Now VISHAY). Its very easy to test with a dmm. I don't remember this cluster off hand but it does look like it could be being used for polarity protection in your photo so its a likely suspect for no input voltage to your VR. Its possible your VR is shorted as well. With the unit unhooked and caps drained, test for a short or open on the diode. If present remove diode and test for short on the VR. If not short then connect the unit back up with the missing diode and see if it works. If it does then replace the diode with a compatible part for future protection of circuit.