I just took a look under the hood of my 98 C230. Different engine but there might be similarities. There is a diagram under the hood (on the hood pad) that shows some of the lines that relate to emissions, including the ones to the switching valve. On the intake manifold back corner driver side I have a gray tube that goes across and over the rear of the engine, then to a right angle connector and down and presumably through the firewall, likely for the climate control system. Hope any of that might help.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra