Tach Always Indicates Too High Or Too Low - No Tach Indication/Tach Indication Erratic

Ensure engine is operating properly and is not misfiring. Disconnect battery ground cable. Remove cluster. Measure resistance between pin No. 20 of cluster connector "A" and ignition coil. Wiggle connections and wiring near ignition coil to check for intermittent connection. If resistance is less than 100 ohms, replace cluster and affix odometer sticker to door pillar. Recheck operation. If resistance is greater than 100 ohms, check wiring in circuit No. 11 for open circuit.