On Board Computer - Engineer Settings

Does any know how to get into the more detailed settings. I have a 4:3 set, and someone mentioned you can hold MENU down and something to get to the diagnositics screen? Any ideas?

Not sure on the E30, but on the E32 you hold 1000/10 down simultaneously and test will apprear, then scroll down using the 10 button until you get the function you desire (need a code book and I have one for E32 I will share if you email me [email protected]) then hit s/r and the readout pops up.