Diagnostic LED mystery (non-responsive after clearing codes) 1992 500E
 

My New Toy: 1992 500E (124-036)...

The “Diagnostic Module” has stopped responding to code reading efforts.

When I picked up the car & checked for codes, the diagnostic module reported code #6 (idle speed control faulty) and #17 (data exchange fault between individual control module). I then successfully cleared both stored codes.

Now when I query the system, there is no response. The LED will light up when pushing the button, but when the button is released the LED goes out, but there is no read-back of anything – not even the “one blink” / O.K. signal.

I’ve read through the archives for hours, but I can’t find any reference for a situation like this. Any input would be GREATLY appreciated!

Thank you in advance…
Glenn


Note: this situation exists at both the factory 16 pin connector with the built-in LED, or with the home-made LED tool at port 19 on the 38 pin “X11/4” connector.

No Led feedback initiation until the car has gone through all Self-Test Emmisions procedures.
Takes a few drive cycles............................