I have a 1994 E320, California emissions 104 engine. Because this is a California car, it has a pushbutton in position 2 of the diagnostic panel by the battery and LED in position 4. The check engine light came on and, following info in other threads on this forum, after pushing the button for 3 seconds then releasing, I get 6 flashes on the LED. Can anyone help diagnose the probable cause? Thanks in advance!

Code 6 on the DM is "idle speed control faulty", which is really just telling you to read the codes on pin 14, which requires building the flash code reader. Try a search, also this thread - E320 16 PIN DTC Charts inc. pin 8, pin 14