I'm sure someone has run into this before.

Still haven't changed the cluster in my 00 LS, but I just put in a 96 spec JDM ITR.

All is well other than the tach which is quite erratic. Essentially, once I hit above 6500 rpm, it bounces all over the place. I expected it to be off until I put in the ITR cluster, but not bouncing all over like that.

 

Just in case anyone else runs into this. The tach signal is not accurate coming from the ignition signal at the ECU and needs to be wired from the distributor. This only applies to JDM ECUs I believe. It seems that USDM ECUs derive the tach signal from the CKF sensor, which is non-existent on JDM ECUs, at least not on OBD2a. The distributor is wired for tach signal, but in most USDM OBD2b cars, the signal stops at the plug and does not continue through the chassis harness.

In this case the distributor worked just fine. The tach signal would simply jump around above 6000 rpm when taping in the ignition signal output from the ECU .

Having said all this, I don't recall anyone running into this problem with OBD2b Civic or JDM clusters, but that may just be the luck of the draw.