125000619 - K91 INSTRUMENT LIGHTS / LIGHTING DIMMER NOT WORKING

With the ignition ON and the side lights on, the instrument lights up, but the brightness remains constant when the controls are adjusted.
the side lights are working properly
Results of the tests
1CONTROLS CHECKAll OKProblems metOperation
Check that the + / - Mode buttons on the Computer left controls panel are working properly: See    See E2530 INSTRUMENT LIGHTINGContinue to Step 2Switches faultyReplace the control panel Op.    Op. 5560B56 PANEL WITH MULTIFUNCTION DISPLAY AND HEADLAMP ALIGNMENT SWITCHES BUTTONS R R
2ELECTRICAL CIRCUIT CHECKAll OKProblems metOperation

Check:

Continue to Step 3Connections / supplies not correctRestore correct connections / supplies See    See E2530 INSTRUMENT LIGHTING
3CHECK WITH DIAGNOSTIC EQUIPMENTAll OKProblems metOperation
Connect the Examiner Plus or Smart equipment to the diagnostic socket.Check the operation of the panel light through the active diagnosis of the instrument panel.Continue to Step 4Light does not change, instrument panel defectiveReplace instrument panel Op.    Op. 5560B11 ANALOGUE CONTROL PANEL - R+R OR REPLACE
4CHECK ON CORRECT OPERATIONAll OKProblems metOperation
Check that the fault is no longer presentEnd of diagnosis.