I get no voltage at pin 3 of the x11 on my 1992 124/103. I did gat a reading for a bit when the engine was cold, but it went away as the engine warmed up. Any ideas what would cause this. I've tried it with two different meters.

pin 3 on x11 goes to cis ecu.


if you're trying to measure the on-off ratio (measured between pins 3 and 2) then you need a duty cycle meter or an oscilloscope and not just a simple volt meter

Both of the meters I used have duty cycle function. Even with just a meter, I should get a voltage reading with the ignition on and the car not running.

0% on/off ratio possibilities:

1. mixture too rich
2. bad ecu
3. cable to socket 3 of X11 has open circuit


Test conditions:

- engine idling
- oil temp ~80C
- battery voltage 11-14v


page 16 of this manual explains it in detail (you have lambda control) also check for diagnostic codes on page 93 that you check with a blinking light:


http://w124-zone.com/downloads/MB%20CD/W124/w124CD1/Program/Engine/103/07.3-0121.pdf