1995 E320 code 26
 

this is failure of the upshift control relay that works on vacuum.
mentioned elsewhere is that these parts rarely fail. usually problem is a vacuum leak.
well, somebody please help me in the steps to check vacuum. I believe this unit sits just near the brake master cylinder by the firewall.
I think i found it. it looks like the unit has a purge openning on one side and some in/out vacuum lines. nearby are a series of 3 check valves with more vacuum lines.
should I just apply vacuum to every line or is there only one/two critical lines to check?
tan man

The out line of the SOV is green. It goes to thetranny shift servo and it should hold a vac .. if not , it most likely has a bad element.