198001806 - K001 REV COUNTER NOT WORKING

With the engine running, the rev counter does not work or works irregularly.
1CHECK USING DIAGNOSTIC EQUIPMENTALL OKPROBLEMS ENCOUNTEREDACTION
Connect the Examiner diagnostic equipment to the diagnostic socket.Check that there are no faults in the instrument panelMove on to Step 2Presence of errorsContinue following the instructions for the diagnostic equipment
2ELECTRICAL CIRCUIT CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check connections between instrument panel, Body Computer and engine management control unit    See E5030 PETROL ENGINES ELECTRONIC MANAGEMENT Move on to Step 3Wiring defectiveRepair/replace the wiring.
3CHECK USING DIAGNOSTIC EQUIPMENTALL OKPROBLEMS ENCOUNTEREDACTION
Keeping the Examiner equipment connected to the diagnostic socket, check the operation of the display in active diagnosisMove on to Step 4Rev counter not working through stepping motor failureReplace the Instrument Panel    Op. 5560B10 CONTROL PANEL - R+R
4CORRECT OPERATION CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check that the fault is no longer presentEnd of diagnosis