Thanks Arthur for the next step.
Plugged the throttle actuator back in just in case its absence might screw up the readings.
Using the hand built led tester I got error codes 2 and 11 from pin 14 EA module.
From the code book:
Error 2 is - Closed throttle recognition signal to engine control module (HFM-SFI or Left LH-SFI)
Fuel safety shut-off to engine control module (HFM-SFI or left or right LH-SFI)
Error 11 is - EA/CC/ISC control module (N4/1) or Safety contact switch (M16/1s1) or Stop lamp
switch or Cruise control switch or Actual value potentiometer or Starter lock-out/back-up
lamp switch or engine speed signal or vehicle speed signal or closed throttle position
switch or safety relay in EA/CC/ISC control module
This vehicle has 160,000 KM, the neutral safety switch, ignition switch and some fuses were replaced recently to fix a no start problem. Further, in addition to the CEL being on, I do have a stop lamp indicator on, even though I believe all stop lamps are fine. This car still has the original harness.
The question is: is it the actuator or the control module? Remember the actuator is making grinding/squeaking noises when the ignition is on or the car is driving. I was thinking of opening up the actuator just to id the sound source and check for shorts.
Mercedes Canada quoted $1777.00 CDN for the actuator. Checking one other source.
Thanks again for any help,