What is the purpose of the ETA? I always assumed that was the CIS-ECU. ...
As the name “E
ctuator” suggests, the ETA controlls the throttle valve electronically. …
... I was unable to record a resistance or connection between terminal 20 and 21 or terminal 21 and 2. This is at a temperature of about 32 F. I visually inspected the sensor and it appears that at one point the plastic shroud around the sensor had been broken, and the terminals had been surrounded in electrical tape! I've been looking for this part online since discovering this but I've been unsuccessful. Does anyone have a source for these type of parts or is this a junkyard part? ...
If there is no connection (infinite resistance) between terminal 21 & 2 and between terminal 21 & 20, then there is a problem with at least one of the following:
- CTS (Coolant Temperature Sensor)
- connection of the CTS to the ECU connector (wire / plug)
- connection of terminal 2 to engine ground (wire / plug)
- connection of terminal 20 to ground (wire / plug)
That CTS (B11/2, see attached drawing) is a double sensor. On your 300SE (produced 11/88) there should be two separate plugs connected to it (one with a green/black cable and one with a green/red cable). One goes to the ignition control module, the other one goes to terminal 21 of the CIS-ECU. Which of the two pins which plug / cable is connected to doesn’t matter.
To check the sensor itself, measure the resistance from each of its two pins to engine ground twice … once when the engine is cold … once when the engine is at operating temperature.
... I measured the play today, and it was at just over 1/4 inch. So yeah, around 7-8 mm.
Not to blame you, but to illustrate the value of correct / precise reporting:
In post 39 I suggested some tests on the AFM, which included checking its play and I said that the play should be 1-2 mm and “latest after about 2 mm! you should feel the other end of the AFM lever reach the CP.”
In post 40 you replied:
“I tried all these tests and they've all been passed … “
Very early in this thread I mentioned the possibility of a problem with the FD‘s basic setting via Lambda adjustment screw, which seems to be the case here. Obviously someone messed with that screw. … And it looks like a case of neglected maintenance. …
Let’s first take care of the problem with the CTS signal … and get prepared to switch your California version CIS-ECU to duty cycle output to the round diagnostic socket X11 according to 07.3-0121 pg 97/98, as mentioned in post 55.