Hello. I have a 1987 300D. With an inop tach, ac fan won’t turn on, low idle and abs light on, on the dash. I tested the OVP relay which appears to be good. ELR is also not working.
Speed sensor on transmission is attached and cleaned.

Before I removed the OVP to test it, the tach would come on after a while of driving it, most of the time.

I wondering if I have some sort of bad wiring connecting these system? I’m lost. Any help would be appreciated.