95 E320 CEL, onboard code reader doesn't blink
 

Just bought an E320 that seems in good shape, but have a slight problem.
The check engine light is on, but when I press the button at #2 on the diagnostic box, all I get is a relay click after about half a second and then a solid LED. No blinks.

Do I still have to use jumpers to read codes with the onboard pushbutton reader?

I fiddled with the #3 fuse immediately before the CEL came on to see if corrosion or the dimmer pot was to blame for the instrument lighting not coming on.

Did some more research and discovered the onboard tester only deals with emissions. Plugged in my external tester and cleared the codes, who knows when they were last cleared.

Here's a document that may help you. Courtesy of GSXR.

http://www.w124performance.com/docs/mb/diagnostics/DTC_List_W124_M104.pdf