tachometerstoppedworkingwhatcanilookfor

This is Russell Boulding from RB Auto Service in Pinellas Park. We specialize in Cadillac. The first thing to check is for stored diagnostic trouble codes in the ECM (engine control module) and EBTCM (electronic brake and traction control module). On the Catera certain DTC's will cause the tachometer to be inoperative. If there are DTCs they will need to be diagnosed but you can clear them and see if the tach comes back before they codes reset. If there are no codes or if clearing them does not resolve the issue. I would check with a scan tool to see what the ECM is seeing for RPM. The RPM value is first read by the ECM and then transmitted to the IPC (instrument panel cluster) if the PCM is not seeing the right value it could be a sensor or wire issue. If the ECM is seeing the correct RPM the problem is with the tach output circuit from the ECM to the IPC or with the IPC itself. That will give you a direction to go in. Let me know if you need more help.