Testing the Onboard Computer (OBC)

From BMW E34 Encyclopedia

If your car has an OBC with 1000,100,10,1 button, there is an easy way to test if the OBC is not getting power or if the bulbs are burned out. Turn the key position number two: Press TIMER. Press SET-RES. The TIMER button has a little red light that should light up now. If the light lit up, your OBC is getting power.