K91 Instrument lights light dimmer not working

Fault diagnosisK91 Instrument lights light dimmer not working

With the ignition turned on ON and the side lights on, the instruments are properly lit but the intensity is not adjustable.

Step	Test procedure	Result	Action
1	CHECKING INSTRUMENT LIGHTING DIMMER BUTTON Check instrument lighting dimmer button operation (Wiring diagram E2530 INSTRUMENT LIGHTING ).	OK	Move onto step 2
1		Instrument lighting dimmer button faulty	Repair or replace the instrument lighting dimmer button Op. 5540C18 End of diagnosis
2	CHECKING INSTRUMENT LIGHTING DIMMER ELECTRICAL CIRCUIT Check, in order: Connection between speedometer and instrument lighting dimmer control lighting dimmer control earth connection between speedometer and other instruments connection between stalk unit and instrument lighting dimmer control (Wiring diagram E2530 INSTRUMENT LIGHTING ).	OK	Move onto step 3
2		Connection broken	Restore connection End of diagnosis
3	SPEEDOMETER CHECK Check operation of the speedometer, particularly the instrument lighting dimmer function: see DESCRIPTION AND OPERATION: 5560 Instruments (see 5560F)	OK	Move onto step 4
3		Instrument not working	Replace the speedometer Op. 5560B02 End of diagnosis
4	CHECK CORRECT OPERATION Check that the fault is no longer present	OK	End of diagnosis
4		Fault persists	Incorrect selection of diagnostic procedure

Parts & tools for this job For 1997 Alfa Romeo 156

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