The altitude correction capsule has no vacuum line attached to it.
It supposed to read a barometric pressure and send proper signal
to ECU. With increasing altitude, decreasing air pressure, the mixture will be adapted to the altitude by a reduction of the voltage. I am still not in the clear what are you trying to do!
Are you checking voltage at air flow position sensor, or are you checking current at EHA?
I assume your 190 has 8 valve engine.
For 8 valve engine static current at EHA approx 20mA.
To check static current turn egnition key on, engine off. Unplug coolant temp sensor. Pull plug from the EHA just a little bit, enough to get to pins. Plug must be connected to EHA. Set your multimeter to mA. Measure current between pins.
Since you will be working with EHA you need to check the resistance of EHA as well. Turn egnition off. Disconnect plug from EHA. Set your multimeter to Ohms. Measure resistance between pins, it should be 19.5 +/- 1.5Ohms. If the resistance is different then specified, you need to replace EHA.
Now! I sort of jump to a middle of the procedure of testing CIS-E.
There are many test steps preceding the above tests.
To completly evaluate the performance of CIS you need to start at the begining. Let me know what is the problem with your engine, and what are you trying to accomplish.