Dont know what model or year auto, but earlier BMW's used service
lights in the cluster. This service light used two batteries to hold
the memory, and as they got old they would leak acid down onto the
If you are lucky its only a battery replacement, but from my experience
acid eats the traces on the board thus ending operation of many gauges.
I was able to solder wires in place of the circuit traces and install
new batteries. Everything is back to snuff again.
Requires removal of the guage cluster.