OBD1 Pin connections

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

Reply to
Guenter Scholz
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Check your email for a diagram from the MB WIS software.

Reply to
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Perfect Doug, many thanks!

cheers, guenter

Reply to
Guenter Scholz

Reply to
Wan-ning Tan

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

Reply to
Guenter Scholz

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