This picture shows the location of the modulator. But if your 190e is like mine it will be red rather than black. The rubber dust cap is about the size of a dime. As I stated in my prior post it's really hard to get to. I had to replace mine because the bladder broke inside mine, sending trans. fluid up into the intake manifold. I had to roll the transmission to get to it. I then adjusted it with a medical clamp.
90 190 E 2.6 162K
91 300 E 117K
90 Laser RS turbo 169K
"The one who dies with the most toys wins"