I have a 1988 300E (Canadian Version, i.e. no switch/LED at the diagnostic plug next to the battery) and my car is losing power. Everything has been changed (spark plugs/wires, O2 sensor) etc....
Still, no improvement. I would like to be able to read what fault code (if any) has been set in the computer (and to reset them). I've read that I can build a LED counter (which uses pin 1 and 3), however, pin 3 on the diagnostic plug (next to the battery) doesn't have anything in it (it's just a hole)....the pins that are available are pin 1, 6 and 7.
Any advice would be greatly appreciated.