Hi all,
I've put together a little serial code reader for my '89 300E that is running OK but not well... idle is rough.... and I 'will' track the problem down. Which pins on my X11 socket that accesses the ECU will read the most important codes. Appreciate any help.
cheers, guenter
ps I know pin 3 displays the oxygen sensor for example
Check your email for a diagram from the MB WIS software.
Perfect Doug, many thanks!
cheers, guenter
the code reader is rather trivial. simply a momentary push button switch wired in series with an LED (+resistor if it's not internal to the LED). Then the other end of LED goes to batterie's +'ve and the other end of switch to battery's -'ve. The connection between LED and switch has a third connection added (either at LED or switch terminal) that will go to the pins of X12 connector (it has a plastic cap with the sockets for the wires) and is on secondary firwall near battery. Again, I know for certain this is the case for 88 and 89 W124's (103 engine) but not sure of other years. One then simply presses switch for a few seconds to activate ECU that then blinks the LED a number of times to spell out the difficulty it thinks exist. One blink means no problems. Moreover, you can then also erase any stored codes again.
I can send you more detailed information/pictures if you need
cheers, guenter
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