Tachometer Not Operating Properly

Turn ignition off. Press and hold TRIP/RESET button on instrument panel. Turn ignition on. Mechanical Instrument Cluster (MIC) self-test will start. All gauges including tachometer should sweep from zero to full scale, and back to zero. If all gauges pass self-test, go to SELF-DIAGNOSTICS - GRAND CHEROKEE article in ENGINE PERFORMANCE. If tachometer fails self-test, replace tachometer. See appropriate INSTRUMENT PANELS article. Perform BODY VERIFICATION TEST  under VERIFICATION TESTS.