Revving 4000 rpms on the highway

that would be 75% of the V8 readings, pretty close at 3200 with normal convertor slippage. Ive never come across an tacj with the 6 cyl loop/switch enabled, seem to all come off V8s......
yes! so its the tach? The RPM calculator said I should be around 3200 RPM. Should I pull the cluster and check the back?