Bringing this topic from the dead.
2000 Civic Ex with a 1994 gsr & obd1 p72.
stock ex harness with ecu & distributor jumper harness.
problem: no rpm signal. Already tried splicing from the dizzy signal wire to the back of the tach.

 

Test continuity of blue rpm wire from ICM to cluster.

Check for rpm from ICM and blue wire using frequency (Hz) setting on multimeter.

Test tach in cluster.

 

Ill try that, however I’ve used 2 different clusters and a different dizzy. Would the crank position sensor have a play in this?

 

A multimeter will solve the mystery.

No

 

Its probably the jumper harness, is it a OBD2B distributor jumper harness?, The 2000 civic is OBD2B it gets the RPM signal from the ECU.