341509 - D75 THE CRUISE CONTROL IS NOT WORKING

The Cruise Control system does not decrease the speed when the ring nut is turned to " -".
STEPOPERATIONS TO BE CARRIED OUTTEST RESULTS
1CHECK USING DIAGNOSTIC EQUIPMENTALL OKPROBLEMS ENCOUNTEREDACTION
Connect the diagnostic test equipment (Examiner or other instruments) to the tester input.Check for the presence of faults in the engine management control unitMove on to Step 1. Error detected in the control unit1. Continue following the instructions for the diagnostic equipment
2. No communication with the control unit2. Restore the connection between the engine management control unit and the diagnostic connector (Wiring Diagram ) E5060 CRUISE CONTROL
2SELECTOR CONTROL CHECKALL OKPROBLEMS ENCOUNTEREDACTION
Check that the Cruise Control contacts are working properly in the "-" position    Continue following the instructions in the test 5580AD Cruise Control SET- control checkMove on to Step No continuityReplace the steering column switch unit lever with the Cruise Control incorporated    See in Op. 5580A10 Cruise control LEVER ASSEMBLY - R.R.
3SUPPLY CHECKALL OKPROBLEMS ENCOUNTEREDACTION
With the ignition key in the ON position and the Cruise Control in the ON and "-" position, check that there is a voltage signal from the Cruise Control to the engine management control unit (Wiring Diagram ) E5060 CRUISE CONTROL Move on to Step No voltage detectedRepair the connections (Wiring Diagram ) E5060 CRUISE CONTROL
4CHECK ON CORRECT OPERATIONALL OKPROBLEMS ENCOUNTEREDACTION
2.4 20 V,2.0 TB,3.0 V6Check that the fault is no longer presentFault persists control unit defectiveReplace the engine management control unit    See in Op. 1056B82 Injection/ignition system CONTROL UNIT (one) - R.R.
4CHECK ON CORRECT OPERATIONALL OKPROBLEMS ENCOUNTEREDACTION
Check that the fault is no longer presentFault persists control unit defectiveReplace the engine management control unit    See in Op. 1060G80 Diesel electronic injection system CONTROL UNIT - R.R.