1985 California-spec 300TD.

Tach currently inop. Tach sensor shows 1.8 KOhms and 5+ VAC at idle when measured at the connector in the engine compartment. Fuse atop the OVP relay is good (and all other functions work, so assume the OVP relay itself is good).

Where is the next place I can check for the signal from the tach, and what should the reading be? I'd check at the input to the EGR computer, but can't figure the trick to get the connector off the EGR box itself.

Assistance please...

Thanks,
Dave