In the combination cluster instrument one of the many (hot) wires might be chafing and grounding. Use test light to troubleshoot wire by wire or start pulling fuses one by one with ignition off, on, start etc. The instrument is combine: cooling temp gauge, fuel gauge, speedo light, batt. charge light, oil press ind., turn signal etc, etc, for the manual. The automatic has more garbage. You mention that temp. sensor was replaced, now try this , hook eng. temp wire to old temp sensor and without grounding sensor start engine if it shows same problem go to above.